Cancer of the testicles, primarily the germ cells, is a highly treatable disease common to young men. This article describes how chemical biomarkers are central to the diagnosis, characterization, therapeutic monitoring, prognosis and long-term surveillance in patients with testicular cancer.
by Dr Angela Cooper and Dr Seán Costelloe
Incidence of testicular cancer
Testicular cancer (TC) is relatively rare, accounting for approximately 0.7% of all UK male cancers, with a worldwide incidence estimated as ~7 per 100 000 [1, 2]. Incidence of TC has noticeably increased in industrialized countries over the last few decades, particularly in white males of European descent, although the reasons for this remain unclear [2–5]. Amongst younger men aged between 15 and 49 years in the United Kingdom and the United States of America, TC is the most common type of cancer observed [2, 3, 6, 7].
Classification of TC
Approximately 95% of malignant TCs originate from primordial germ cells, also known as germ cell tumours (GCTs) [3, 7–9]. However, rarely these malignancies may arise from extragonadal primary sites such as the retroperitoneum, mediastinum or pineal gland [3–5, 8, 10]. Germ cell tumours classified as seminomas (~40%) are predominantly formed of uniform cell types, whereas non-seminomatous germ cell tumours (NSGCTs), also accounting for ~40% of GCTs, originate from multiple cell types such as embryonal carcinomas, teratomas, choriocarcinomas and yolk sac carcinomas. GCTs arising from mixed germ cells comprise the remaining 20%. The World Health Organization (WHO) classification system for testicular tumours (Table 1) define five basic GCT types based on histological examination:
- Seminomatous GCTs
- Non-seminomatous GCTs (NSGCTs)
- Embryonal cell carcinomas
- Yolk sac tumours
- Teratomas
- Choriocarcinoma
The vast majority of non-GCTs are sex cord-gonadal stromal tumours involving the Sertoli or Leydig cells of the testicles, and are often benign [8, 9, 11].
‘Burned-out’ GCTs, or spontaneous regression of a testicular GCT, is a very rare phenomenon occasionally observed in male patients presenting with metastatic malignancy with an absence of primary testicular tumour. Often, the only remaining evidence of malignancy are features such as homogeneous scarring, hemorrhage, intratubular calcification and testicular atrophy. This may be associated with choriocarcinomas or teratomas [5, 12].
Testicular GCTs exhibit very diverse histology and immunostaining profiles, and have varying clinical progression and prognosis outcomes as demonstrated by the numerous methods of GCT classification systems. It is outside the focus of this paper to consider histology or immunostaining used in the identification and differentiation of GCTs, as these topics has been extensively documented in other review articles.
Treatment and cure rates in TC
Advances in treatment strategies, such as the use of cisplatin therapies [13], careful staging at diagnosis, early intervention using multidisciplinary teams, rigorous surveillance follow-up, and salvage therapy, means that GCTs are highly curable. Currently, expected cure rates of 95% are observed in patients who receive a TC diagnosis, and cure rates of 80% in patients with a diagnosis of metastatic TC [3, 13].
Causes and presentation of TC
The causes of TC cancer are still unknown, although cryptochordism is the best-characterized risk factor associated with TC. Research has shown that timing of orchiopexy impacts on future risk of TC development, suggesting hormonal changes during puberty are strongly associated with TC etiology in males. However, prenatal risk factors, environmental exposures in adulthood, male infertility, certain genetic or congenital disorders such as Down’s syndrome, Klinefelter’s syndrome, human immunodeficiency virus infection and intersex patients have also been associated with an increased TC risk [3, 5, 7].
Presentation of TC is often a painless lump in the testis body, but due to a frequent lack of pain, medical opinion is frequently delayed. A testicular mass or swelling, or episodic diffuse pain may be observed. More rarely, metastatic symptoms such back pain arising from retroperitoneal lymph node involvement, or coughing, pain or hemoptysis due to lung metastasis may be reported [3, 7, 8].
Diagnosis and staging of TC
Clinical suspicion of TC, such as altered testicular shape or non-painful swelling, should prompt a full physical examination and patient history, imaging to include testicular and abdominal ultrasound, as well as chest X-ray [14]. If metastasis is suspected, chest, abdominal and brain computerized tomography (CT), and bone scintigraphy should be undertaken [9]. Final diagnosis and prognosis requires biopsy sampling for histology and immunostaining profiling as appropriate, and in the majority of cases, treatment options should be based on the histology results [10]. Biochemical analysis should include initial concentrations of serum tumour markers (STMs). Metabolic biochemistry, liver function tests and a full blood count should be undertaken to determine general organ function, and may demonstrate evidence of metastasis [9].
This collective information can be used to reference the Tumour-node-metastasis (TNM) Classification of Malignant Tumours staging system (Table 2). This cancer staging system is based on primary tumour site, nearby lymph node involvement, and presence of distal metastatic spread from initial primary tumour site [4, 15]. The use of STMs as a fourth staging system has added diagnostic and prognostic value, independent of the TNM system (Table 3) [9]. The decision for chemotherapy or radiotherapy treatment for non-surgical metastatic disease is based on CT and/or magnetic resonance imaging (MRI) results, and concentrations of STMs [4].
The majority of patients (~75%) presenting with a testicular mass are diagnosed at stage 1 [7, 8]. At this stage, treatment options are typically surgery with an excellent cure rate. For metastatic disease, combinations of surgery, chemotherapy or radiotherapy are required depending on cancer mass, location and distal lymph node involvement [13]. Greater than 80% of patients with metastatic GCTs are successfully treated and cured.
Treatment of TC
TC cells are extremely sensitive to chemotherapy [9, 10]. Specifically, the standard chemotherapy regime consists of 3 or 4 cycles of bleomycin, etoposide and cisplatin (BEP) chemotherapy, or etoposide and cisplatin (EP) chemotherapy every 21 days [8, 9]. Surgery may be considered to remove residual masses post-chemotherapy. Data suggests a higher relapse rate in patients with NSGCTs than seminomas following an initial chemotherapy regime. This relapse rate can be used to further classify patients into good, intermediate and poor prognostic groups, using a combination of STM concentrations and location of primary tumour or metastases. Around 50–99% of patients can still expect to survive [8].
Salvage therapy, often in combination with chemotherapy, is reserved for patients who have relapsed, or for patients where cancer progression continues after following a standard chemotherapy regime. High-dose chemotherapy with autologous bone marrow transplant is a controversial approach for patients with a poor prognosis, and where a standard chemotherapy regime and salvage therapy has been unsuccessful. Initial studies are encouraging but further trials are required. A small cohort of patients have been identified who suffer a late relapse, i.e. >2 years post-diagnosis but also potentially ≥10 years post-diagnosis. These patients are less responsive to chemotherapy, so are treated primarily with surgery. Unfortunately, less than half will remain disease-free following surgical intervention [8, 9]. Chemotherapy-induced side effects are governed by the dose and combination of drugs used. This has triggered more recent trials designed at maintaining a cure rate but with reduced associated chemotoxicity [8].
The use of serum tumour markers in TC
The discovery of serum and urine tumour markers and the advent of chemotherapy have significantly improved cancer staging, management and prognosis in patients with TC. The benefit of initial STMs is predominantly with regard to disease staging, whereas serial STMs are particularly useful for monitoring response to treatment after surgery, chemotherapy or radiation therapy. STMs are useful because they are often detectable well before clinical radiological detection in patients. Furthermore, concentrations can be helpful to differentiate GCT type. The detection of at least one elevated STM occurs in ~85% of NSGCTs, and the presence of elevated STMs occurs in significant numbers of pure seminoma cases [9, 10]. However, in rare cases where patients present with evidence of a testicular mass, radiographic evidence of metastatic disease, with significantly elevated alpha-fetoprotein (AFP) or human chorionic gonadotrophin (hCG) serum concentrations, it is advised that treatment is not delayed while awaiting histology results [10].
The American Society of Clinical Oncology recommend against using STMs as a screening test for GCTs in asymptomatic males. Given the low incidence and mortality of TC combined with the high cure rate, it is suggested a screening programme would be neither cost-effective nor decrease mortality [10]. Furthermore, although STMs can be helpful in combination with imaging techniques in the diagnosis of TC, normal STMs alone do not exclude TC and may also be raised in other conditions [3, 8–10]. Routine testicular examination via palpation is recommended in all males from puberty up to ~45 years. This is of particular importance for males with a past medical history that may suggest an increased GCT risk as detailed previously.
Commonly employed serum markers include: AFP and hCG as mentioned previously, hCG beta-subunit (hCGb), placental alkaline phosphatase (PLAP) and lactate dehydrogenase (LDH). Alpha-fetoprotein levels are elevated in teratocarcinoma or testicular embryonal carcinoma, while conversely, AFP is never elevated in pure seminomas. Human chorionic gonadotrophin elevations are associated with 10–15 % of pure seminomas. Lactate dehydrogenase is an enzyme found in all cell types, meaning it is less specific for TC, although it does have prognostic value in advanced stage GCTs [3, 9]. A decline in serial STM concentrations is useful to detect the presence of residual disease following surgery, or to assess response to chemotherapy. In both scenarios, the decline in STM concentrations should follow the half-lives of each marker [9].
There are detailed STM surveillance guidelines in place following surgery, which recommend a meticulous timetable of STM measurements and radiology imaging to detect disease recurrence depending on initial GCT type, thereby avoiding relapse and presentation at a later date with advanced stage disease [8, 9].
Future focus
While the majority of patients diagnosed with TC will survive, challenges still persist. Serum tumours markers have been pivotal to improved outcomes for patients with and without metastatic disease. Future research is focused on patients with an initial poorer prognosis, patients who have relapsed following first-line chemotherapy and patients who have a late relapse. Long-term health consequences for patients surviving TC, in particular side effects associated with chemotherapy and radiotherapy such as cardiovascular disease, impaired fertility and secondary cancers, continues to drive collaborative studies nationally and internationally to improve TC outcomes for the future.
References
1. Cancer registration statistics, first release, England, 2014. Office for National Statistics 2014. (http://web.ons.gov.uk/ons/rel/vsob1/cancer-statistics-registrations–england–series-mb1-/2014–first-release-/rpt-cancer-stats-registrations.html)
2. Hameed A, White B, Chinegwundoh F, Thwaini A, Pahuja A. A review in management of testicular cancer: single centre review. World J Oncol. 2011; 2: 94–101.
3. Bosl GJ, Motzer RJ. Testicular germ-cell cancer. N Engl J Med. 1997; 337: 242–254.
4. Bahrami A, Ro JY, Ayala AG. An overview of testicular germ cell tumors. Arch Pathol Lab Med. 2007; 131: 1267–1280.
5. Sesterhenn IA,Davis, CJ. Pathology of germ cell tumors of the testis. Cancer Control 2004; 11: 374–387.
6. Wu X, Groves FD, McLaughlin CC, Jemal A, Martin J, Chen, VW. Cancer incidence patterns among adolescents and young adults in the United States. Cancer Causes Control. 2005; 3: 309–320.
7. Hanna NH, Einhorn LH. Testicular cancer – discoveries and updates. N Engl J Med. 2014; 371: 2005–2016.
8. Horwich A, Nicol D,Huddart R. Testicular germ cell tumours. BMJ 2013; 347: f5526.
9. Barlow LJ, Badalato GM,McKiernan JM. Serum tumor markers in the evaluation of male germ cell tumours. Nat Rev Urol. 2010; 7: 610–617.
10. Gilligan TD, Hayes DF, Seidenfeld J, Temin S. ASCO clinical practice guideline on uses of serum tumor markers in adult males with germ cell tumors. J Clin Oncol. 2010; 6: 199–202.
11. Eble JN, Sauter G, Epstein JI, Sesterhenn IA. World Health Organization classification of tumours. Pathology and genetics of tumours of the urinary system and male genital organs. IARC 2004.
12. Ulbright TM. Germ cell tumours of the gonads: a selective review emphasizing problems in differential diagnosis, newly appreciated, and controversial issues. Mod Pathol. 2005; 18: S61–S79.
13. Masters JR, Köberle B. Curing metastatic cancer: lessons from testicular germ-cell tumours. Nat Rev Cancer. 2003; 3:517–525.
14. Suspected cancer: recognition and referral guidelines [NG12]. National Institute for Health and Care Excellence (NICE) 2015. (https://www.nice.org.uk/guidance/NG12/chapter/1-Recommendations-organised-by-site-of-cancer)
15. Sobin LH, Gospodarowicz MK and Wittekind C. TNM classification of malignant tumours (7th ed). International Union against Cancer (UICC). Wiley-Blackwell 2009.
16. Albers P. (Chair), Albrecht W, Algaba F, Bokemeyer C, Cohn-Cedermark G, Fizazi K, Horwich A, Laguna MP, Nicolai N, Oldenburg J. Guidelines on testicular cancer. Eur Urol. 2015. (https://uroweb.org/guideline/testicular-cancer/)
The authors
Angela Cooper* PhD, Seán Costelloe, PhD
Derriford Combined Laboratory, Plymouth Hospital NHS Trust, Plymouth, UK
*Corresponding author
E-mail: angelacooper5@nhs.net
Multisure HIV – the new benchmark for HIV-1/2 screening
, /in Featured Articles /by 3wmediaConfidence in patient testing
, /in Featured Articles /by 3wmediaYour Coagulation Company is a brand of Stago Group
, /in Featured Articles /by 3wmediaThe first lateral flow strip test for detection of Pneumococcus and Legionella in one test!
, /in Featured Articles /by 3wmediaMax Generation
, /in Featured Articles /by 3wmediaCELL-DYN Emerald 22, a compact, easy-to-use hematology analyzer
, /in Featured Articles /by 3wmediaCall for action on diabetes
, /in Featured Articles /by 3wmediaThis year’s annual World Health Day on 7th April highlighted the dramatic rise in the prevalence of Type 2 diabetes (T2DM) and urged global action to contain the epidemic. The number of people suffering from T2DM has approximately quadrupled in three and a half decades; currently 8.5% of the global adult population is affected. Because uncontrolled, elevated levels of blood glucose can eventually result in cardiovascular disease, kidney failure, lower limb amputation and loss of sight, as well as premature death, the disease has major socioeconomic impacts in addition to health issues. Yet it is unlikely, at least in Western populations, that interventions to promote more balanced diets and less sedentary lifestyles will reduce the widespread overweight and obesity that fuels the T2DM epidemic. The general public in the West is continuously informed about the beneficial effects of healthy eating and sufficient physical exercise, but modern working environments, family commitments and social activities often preclude compliance with good health advice. And many of us, healthcare professionals included, think it’s worth taking the risk of eating and drinking (even smoking) what we really enjoy! However, advice once a subject knows that s/ he has prediabetes or T2DM, or is at higher risk because she has suffered from gestational diabetes, is much more likely to be heeded. Thus mass screening programmes are surely the most effective way of curbing the escalating T2DM epidemic.
Many studies assessing the outcome of T2DM screening have reported minimal impact on prevalence. However, some recent community-based screening projects offering testing at a variety of venues including sports grounds, shopping centres, pharmacies (and why not polling stations?) show promise. In such an approach it is clearly simpler to utilise point-ofcare capillary glycosylated haemoglobin (A1c) tests. A finger stick to obtain one drop of blood followed by a short wait in situ for a result that reflects the average blood glucose level over the past three months is clearly preferable to measuring fasting or random glucose levels, tests which require patient forethought, laboratory facilities, larger samples and frequently repeat tests. POC A1c tests are currently available for around €9 a unit, surely cost-effective if a result of prediabetes precipitates patient lifestyle changes, and a diagnosis of diabetes leads to follow-up care.
Of course one must develop clear guidelines for the follow up of subjects with positive test results but surely such screening programmes are more likely to have an effect on the T2DM epidemic than frequently overweight healthcare workers pontificating about healthy diets and exercise?
The clinical chemistry laboratory in the diagnosis and management of testicular cancer
, /in Featured Articles /by 3wmediaCancer of the testicles, primarily the germ cells, is a highly treatable disease common to young men. This article describes how chemical biomarkers are central to the diagnosis, characterization, therapeutic monitoring, prognosis and long-term surveillance in patients with testicular cancer.
by Dr Angela Cooper and Dr Seán Costelloe
Incidence of testicular cancer
Testicular cancer (TC) is relatively rare, accounting for approximately 0.7% of all UK male cancers, with a worldwide incidence estimated as ~7 per 100 000 [1, 2]. Incidence of TC has noticeably increased in industrialized countries over the last few decades, particularly in white males of European descent, although the reasons for this remain unclear [2–5]. Amongst younger men aged between 15 and 49 years in the United Kingdom and the United States of America, TC is the most common type of cancer observed [2, 3, 6, 7].
Classification of TC
Approximately 95% of malignant TCs originate from primordial germ cells, also known as germ cell tumours (GCTs) [3, 7–9]. However, rarely these malignancies may arise from extragonadal primary sites such as the retroperitoneum, mediastinum or pineal gland [3–5, 8, 10]. Germ cell tumours classified as seminomas (~40%) are predominantly formed of uniform cell types, whereas non-seminomatous germ cell tumours (NSGCTs), also accounting for ~40% of GCTs, originate from multiple cell types such as embryonal carcinomas, teratomas, choriocarcinomas and yolk sac carcinomas. GCTs arising from mixed germ cells comprise the remaining 20%. The World Health Organization (WHO) classification system for testicular tumours (Table 1) define five basic GCT types based on histological examination:
The vast majority of non-GCTs are sex cord-gonadal stromal tumours involving the Sertoli or Leydig cells of the testicles, and are often benign [8, 9, 11].
‘Burned-out’ GCTs, or spontaneous regression of a testicular GCT, is a very rare phenomenon occasionally observed in male patients presenting with metastatic malignancy with an absence of primary testicular tumour. Often, the only remaining evidence of malignancy are features such as homogeneous scarring, hemorrhage, intratubular calcification and testicular atrophy. This may be associated with choriocarcinomas or teratomas [5, 12].
Testicular GCTs exhibit very diverse histology and immunostaining profiles, and have varying clinical progression and prognosis outcomes as demonstrated by the numerous methods of GCT classification systems. It is outside the focus of this paper to consider histology or immunostaining used in the identification and differentiation of GCTs, as these topics has been extensively documented in other review articles.
Treatment and cure rates in TC
Advances in treatment strategies, such as the use of cisplatin therapies [13], careful staging at diagnosis, early intervention using multidisciplinary teams, rigorous surveillance follow-up, and salvage therapy, means that GCTs are highly curable. Currently, expected cure rates of 95% are observed in patients who receive a TC diagnosis, and cure rates of 80% in patients with a diagnosis of metastatic TC [3, 13].
Causes and presentation of TC
The causes of TC cancer are still unknown, although cryptochordism is the best-characterized risk factor associated with TC. Research has shown that timing of orchiopexy impacts on future risk of TC development, suggesting hormonal changes during puberty are strongly associated with TC etiology in males. However, prenatal risk factors, environmental exposures in adulthood, male infertility, certain genetic or congenital disorders such as Down’s syndrome, Klinefelter’s syndrome, human immunodeficiency virus infection and intersex patients have also been associated with an increased TC risk [3, 5, 7].
Presentation of TC is often a painless lump in the testis body, but due to a frequent lack of pain, medical opinion is frequently delayed. A testicular mass or swelling, or episodic diffuse pain may be observed. More rarely, metastatic symptoms such back pain arising from retroperitoneal lymph node involvement, or coughing, pain or hemoptysis due to lung metastasis may be reported [3, 7, 8].
Diagnosis and staging of TC
Clinical suspicion of TC, such as altered testicular shape or non-painful swelling, should prompt a full physical examination and patient history, imaging to include testicular and abdominal ultrasound, as well as chest X-ray [14]. If metastasis is suspected, chest, abdominal and brain computerized tomography (CT), and bone scintigraphy should be undertaken [9]. Final diagnosis and prognosis requires biopsy sampling for histology and immunostaining profiling as appropriate, and in the majority of cases, treatment options should be based on the histology results [10]. Biochemical analysis should include initial concentrations of serum tumour markers (STMs). Metabolic biochemistry, liver function tests and a full blood count should be undertaken to determine general organ function, and may demonstrate evidence of metastasis [9].
This collective information can be used to reference the Tumour-node-metastasis (TNM) Classification of Malignant Tumours staging system (Table 2). This cancer staging system is based on primary tumour site, nearby lymph node involvement, and presence of distal metastatic spread from initial primary tumour site [4, 15]. The use of STMs as a fourth staging system has added diagnostic and prognostic value, independent of the TNM system (Table 3) [9]. The decision for chemotherapy or radiotherapy treatment for non-surgical metastatic disease is based on CT and/or magnetic resonance imaging (MRI) results, and concentrations of STMs [4].
The majority of patients (~75%) presenting with a testicular mass are diagnosed at stage 1 [7, 8]. At this stage, treatment options are typically surgery with an excellent cure rate. For metastatic disease, combinations of surgery, chemotherapy or radiotherapy are required depending on cancer mass, location and distal lymph node involvement [13]. Greater than 80% of patients with metastatic GCTs are successfully treated and cured.
Treatment of TC
TC cells are extremely sensitive to chemotherapy [9, 10]. Specifically, the standard chemotherapy regime consists of 3 or 4 cycles of bleomycin, etoposide and cisplatin (BEP) chemotherapy, or etoposide and cisplatin (EP) chemotherapy every 21 days [8, 9]. Surgery may be considered to remove residual masses post-chemotherapy. Data suggests a higher relapse rate in patients with NSGCTs than seminomas following an initial chemotherapy regime. This relapse rate can be used to further classify patients into good, intermediate and poor prognostic groups, using a combination of STM concentrations and location of primary tumour or metastases. Around 50–99% of patients can still expect to survive [8].
Salvage therapy, often in combination with chemotherapy, is reserved for patients who have relapsed, or for patients where cancer progression continues after following a standard chemotherapy regime. High-dose chemotherapy with autologous bone marrow transplant is a controversial approach for patients with a poor prognosis, and where a standard chemotherapy regime and salvage therapy has been unsuccessful. Initial studies are encouraging but further trials are required. A small cohort of patients have been identified who suffer a late relapse, i.e. >2 years post-diagnosis but also potentially ≥10 years post-diagnosis. These patients are less responsive to chemotherapy, so are treated primarily with surgery. Unfortunately, less than half will remain disease-free following surgical intervention [8, 9]. Chemotherapy-induced side effects are governed by the dose and combination of drugs used. This has triggered more recent trials designed at maintaining a cure rate but with reduced associated chemotoxicity [8].
The use of serum tumour markers in TC
The discovery of serum and urine tumour markers and the advent of chemotherapy have significantly improved cancer staging, management and prognosis in patients with TC. The benefit of initial STMs is predominantly with regard to disease staging, whereas serial STMs are particularly useful for monitoring response to treatment after surgery, chemotherapy or radiation therapy. STMs are useful because they are often detectable well before clinical radiological detection in patients. Furthermore, concentrations can be helpful to differentiate GCT type. The detection of at least one elevated STM occurs in ~85% of NSGCTs, and the presence of elevated STMs occurs in significant numbers of pure seminoma cases [9, 10]. However, in rare cases where patients present with evidence of a testicular mass, radiographic evidence of metastatic disease, with significantly elevated alpha-fetoprotein (AFP) or human chorionic gonadotrophin (hCG) serum concentrations, it is advised that treatment is not delayed while awaiting histology results [10].
The American Society of Clinical Oncology recommend against using STMs as a screening test for GCTs in asymptomatic males. Given the low incidence and mortality of TC combined with the high cure rate, it is suggested a screening programme would be neither cost-effective nor decrease mortality [10]. Furthermore, although STMs can be helpful in combination with imaging techniques in the diagnosis of TC, normal STMs alone do not exclude TC and may also be raised in other conditions [3, 8–10]. Routine testicular examination via palpation is recommended in all males from puberty up to ~45 years. This is of particular importance for males with a past medical history that may suggest an increased GCT risk as detailed previously.
Commonly employed serum markers include: AFP and hCG as mentioned previously, hCG beta-subunit (hCGb), placental alkaline phosphatase (PLAP) and lactate dehydrogenase (LDH). Alpha-fetoprotein levels are elevated in teratocarcinoma or testicular embryonal carcinoma, while conversely, AFP is never elevated in pure seminomas. Human chorionic gonadotrophin elevations are associated with 10–15 % of pure seminomas. Lactate dehydrogenase is an enzyme found in all cell types, meaning it is less specific for TC, although it does have prognostic value in advanced stage GCTs [3, 9]. A decline in serial STM concentrations is useful to detect the presence of residual disease following surgery, or to assess response to chemotherapy. In both scenarios, the decline in STM concentrations should follow the half-lives of each marker [9].
There are detailed STM surveillance guidelines in place following surgery, which recommend a meticulous timetable of STM measurements and radiology imaging to detect disease recurrence depending on initial GCT type, thereby avoiding relapse and presentation at a later date with advanced stage disease [8, 9].
Future focus
While the majority of patients diagnosed with TC will survive, challenges still persist. Serum tumours markers have been pivotal to improved outcomes for patients with and without metastatic disease. Future research is focused on patients with an initial poorer prognosis, patients who have relapsed following first-line chemotherapy and patients who have a late relapse. Long-term health consequences for patients surviving TC, in particular side effects associated with chemotherapy and radiotherapy such as cardiovascular disease, impaired fertility and secondary cancers, continues to drive collaborative studies nationally and internationally to improve TC outcomes for the future.
References
1. Cancer registration statistics, first release, England, 2014. Office for National Statistics 2014. (http://web.ons.gov.uk/ons/rel/vsob1/cancer-statistics-registrations–england–series-mb1-/2014–first-release-/rpt-cancer-stats-registrations.html)
2. Hameed A, White B, Chinegwundoh F, Thwaini A, Pahuja A. A review in management of testicular cancer: single centre review. World J Oncol. 2011; 2: 94–101.
3. Bosl GJ, Motzer RJ. Testicular germ-cell cancer. N Engl J Med. 1997; 337: 242–254.
4. Bahrami A, Ro JY, Ayala AG. An overview of testicular germ cell tumors. Arch Pathol Lab Med. 2007; 131: 1267–1280.
5. Sesterhenn IA,Davis, CJ. Pathology of germ cell tumors of the testis. Cancer Control 2004; 11: 374–387.
6. Wu X, Groves FD, McLaughlin CC, Jemal A, Martin J, Chen, VW. Cancer incidence patterns among adolescents and young adults in the United States. Cancer Causes Control. 2005; 3: 309–320.
7. Hanna NH, Einhorn LH. Testicular cancer – discoveries and updates. N Engl J Med. 2014; 371: 2005–2016.
8. Horwich A, Nicol D,Huddart R. Testicular germ cell tumours. BMJ 2013; 347: f5526.
9. Barlow LJ, Badalato GM,McKiernan JM. Serum tumor markers in the evaluation of male germ cell tumours. Nat Rev Urol. 2010; 7: 610–617.
10. Gilligan TD, Hayes DF, Seidenfeld J, Temin S. ASCO clinical practice guideline on uses of serum tumor markers in adult males with germ cell tumors. J Clin Oncol. 2010; 6: 199–202.
11. Eble JN, Sauter G, Epstein JI, Sesterhenn IA. World Health Organization classification of tumours. Pathology and genetics of tumours of the urinary system and male genital organs. IARC 2004.
12. Ulbright TM. Germ cell tumours of the gonads: a selective review emphasizing problems in differential diagnosis, newly appreciated, and controversial issues. Mod Pathol. 2005; 18: S61–S79.
13. Masters JR, Köberle B. Curing metastatic cancer: lessons from testicular germ-cell tumours. Nat Rev Cancer. 2003; 3:517–525.
14. Suspected cancer: recognition and referral guidelines [NG12]. National Institute for Health and Care Excellence (NICE) 2015. (https://www.nice.org.uk/guidance/NG12/chapter/1-Recommendations-organised-by-site-of-cancer)
15. Sobin LH, Gospodarowicz MK and Wittekind C. TNM classification of malignant tumours (7th ed). International Union against Cancer (UICC). Wiley-Blackwell 2009.
16. Albers P. (Chair), Albrecht W, Algaba F, Bokemeyer C, Cohn-Cedermark G, Fizazi K, Horwich A, Laguna MP, Nicolai N, Oldenburg J. Guidelines on testicular cancer. Eur Urol. 2015. (https://uroweb.org/guideline/testicular-cancer/)
The authors
Angela Cooper* PhD, Seán Costelloe, PhD
Derriford Combined Laboratory, Plymouth Hospital NHS Trust, Plymouth, UK
*Corresponding author
E-mail: angelacooper5@nhs.net
Use of serum free light chain analysis in screening for multiple myeloma in primary care patients
, /in Featured Articles /by 3wmediaIdentification of a serum or urine paraprotein is a key element in the diagnosis of multiple myeloma. Traditionally, this has been achieved using a combination of serum and urine electrophoresis, but this can result in incomplete investigation. The use of serum free light chains as an alternative screening test has been advocated to overcome this.
by David Baulch and Beverley Harris
Multiple myeloma
Multiple myeloma (MM) accounts for 1% of all cancers, with nearly 5000 people in the UK being diagnosed each year. The average age of presentation is 70 with only 15% of patients presenting at less than 60 years of age [1]. Its prevalence has increased by 11% in the last decade, due mainly to increased survival rates in those diagnosed [2]. Despite this, MM still accounts for around 2700 deaths annually in the UK and over 70 000 worldwide with a median survival of only 3–4 years from diagnosis [3].
MM is characterized by the accumulation of clonal plasma cells, predominantly within the bone marrow, and subsequent clonal expansion of the plasma cell lineage [4]. It is almost always preceded by a premalignant, asymptomatic period of monoclonal gammopathy of undetermined significance (MGUS) [1]. The process of immunoglobulin (Ig) production by plasma cells is normally under a state of homeostasis, but random and non-random genetic aberrations, epigenetic changes and atypical interactions within the bone marrow microenvironment can cause uncontrolled proliferation of neoplastic plasma cells, leading to plasma cell disorders (PCDs) such as MM [4]. Clonal expansion of a plasma cell line under such circumstances can cause overproduction of intact monoclonal Ig (IgG, IgA, IgM, rarely IgD and IgE) or monoclonal free light chains (FLCs) kappa and lambda. Although the classification of PCDs is based on the immunoglobulin type secreted, 1–2% of MM cases are classified as non-secretory. This may be due to an absence of secreted monoclonal protein (M protein), or secretion at a concentration below the limits of the laboratory methods used for detection.
Compared with other cancers, diagnosis of MM is challenging. Patients present with a range of non-specific symptoms and as a result often have a string of primary care consultations resulting in diagnostic delay. Such delays significantly impact the clinical course of MM [5], for which a complete cure remains elusive.
Consequences of diagnostic delay
Studies have shown that over 50% of patients attending primary care institutions took 6 months (33% >12 months) from the onset of the first related symptoms to referral [5]. Another study showed the time to diagnosis of MM can be unacceptably prolonged [6] and the pathway to diagnosis in MM was more likely to include a string of repeated primary care consultations, infrequent use of urgent referral routes and increased emergency presentation [7]. In particular, patients whose referral was delayed by 6 months or more were more likely to suffer a greater number of more significant complications such as renal insufficiency which, if swift diagnosis had occurred, may have been reversible [5]. This highlights the need not only to raise awareness of disease symptoms, but to increase the sensitivity of laboratory detection.
Laboratory investigation of multiple myeloma
In addition to clinical and hematological investigations, screening for MM within the laboratory is based on the detection and classification of M proteins by serum protein electrophoresis (the separation of serum proteins according to molecular size, hydrophobicity and electric charge [8]), followed by immunofixation or immunotyping to identify and quantify the Ig isotypes. This method is less reliable for detecting disease when only FLCs are secreted, as these are rapidly cleared by the kidneys. Free light chains in the urine [known as Bence Jones protein (BJP)] can also be detected by electrophoresis followed by immunofixation. However, this methodology is time consuming and may not detect low concentration BJP in dilute urine samples [9]. Interpretation of the results can be difficult and should be performed by appropriately qualified and experienced laboratory staff. In addition, obtaining both urine and serum samples for screening can be problematic, with some laboratories reporting that both samples are received for only ~17% of MM screens.
There is growing evidence to support the direct measurement and quantitation of serum kappa and lambda FLCs in diagnosis, monitoring and prognosis of MM and related PCDs [4]. The serum FLC (sFLC) assay (The Binding Site™) was first developed in 2001 [10]. It is an immunoturbidimetric method using latex-enhanced polyclonal sheep antibodies targeted to epitopes on the light chains of Ig that are exposed when the light chain is ‘free’, i.e. not bound to heavy chain Ig. Results are expressed as a ratio of kappa : lambda light chains.
This sFLC assay can be used to replace traditional urine methods for the laboratory detection of FLCs. This practice has the obvious benefit of using a single serum sample and eliminating the need for a paired urine sample, which may not always be supplied. In addition to the reported increased diagnostic sensitivity of the sFLC assay, an unexpected finding by Dispenzieri et al. was that baseline sFLC results can be used in prognostication and risk stratification of MGUS [11]. Although the rationale for this is poorly understood, it is thought that a greater degree of abnormality in the sFLC ratio reflects an increasing tumour burden.
Studies such as these have informed changes to MM guidelines published in 2016 [12] to acknowledge that significantly abnormal FLC ratios, in the absence of clinical features of end organ damage, can be used in the diagnosis of MM [4]. This eliminates a traditional major challenge with MM diagnosis in that disease definition was clinicopathological. The use of the sFLC ratio in this way therefore marks a milestone in the early detection of MM and highlights a disease transition to being a laboratory-defined rather than a symptom-defined disease, allowing for earlier intervention.
There is, however, controversy as to whether the sFLC assay is indeed a robust candidate for inclusion in PCD screening strategies. There is currently only limited guidance on how it should be used in clinical practice [4] and there is ongoing debate regarding result interpretation, especially for those mildly abnormal ratios. There are, therefore, many considerations to be made before such screening could be implemented.
Study overview and results
Our real-time prospective study aimed to assess the clinical utility of three index laboratory investigations [serum and urine protein electrophoresis (sEP and uEP) and sFLC] to determine the most effective first-line testing strategy for detecting PCDs in primary care patients. These laboratory investigations were performed on 446 samples with no previous history of, or investigations for, MM. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and efficiency were calculated for our current screening tests (sEP and uEP) and the use of sEP with sFLC as an alternative strategy. Figures 1 and 2 outline the process for each of these screening strategies and a summary of the results is given in Table 1.
Conclusion
The purpose of a medical screening programme is to recognize a disease in its preclinical phase to allow intervention at an earlier stage. Such strategies have benefits, risks and costs and the final screening algorithm is often a compromise between these three. However, a proposed screening strategy should fulfil the criteria outlined by Wilson and Jungner in 1968 [13]. Of note, criterion 4 suggests there should be a detectable preclinical stage, in this case MGUS, and criterion 5 suggests there should be a suitable test for screening strategies. This real-time prospective study presents evidence of the clinical utility of the sFLC assay and its use in developing a more sensitive screening strategy for PCD detection.
Standard screening practice combining sEP and uEP increased the sensitivity of the constituent index tests (78% and 30% respectively) to 81%, meaning the addition of urinalysis to sEP increased the sensitivity by only 3%. This reinforces the need for a more sensitive method for detecting sFLC than sEP alone. This combination also displayed a good PPV without compromising efficiency (98%). Despite this, its use missed significant cases of PCDs including a light-chain multiple myeloma, a possible but unconfirmed (in the time frame of the study) case of MM and 10 cases of MGUS, highlighting its limitation as a first line screening investigation.
Combining sEP with sFLC analysis increased the sensitivity from sEP alone by 20% (data not shown), again suggesting singular sEP testing is not sensitive enough to detect minor abnormalities in FLC production. This proposed combination of screening tests increased sensitivity by 17% when compared with current protocols, indicating that the sFLC assay is more sensitive than urinalysis for detecting PCDs. The sFLC assay has been demonstrated to show a high sensitivity for light chain MM and non-secretory MM [14]. These often present with normal sEP and uEP, especially in low tumour burden stages when renal function remains adequate, which may explain the increased sensitivity of sFLC over uEP.
The results of this study confirm also those of others [15], which show that the addition of sFLC analysis to sEP increases the detection of MM and related PCDs. In our case, there was a 17% increase in patients with a PCD detected. However, a concurrent rise in false positive results (10%) was also seen when compared to traditional screening protocols. Investigation into this was beyond the scope of our study, though the false positive rate could potentially be reduced by employing screening strategies that apply renal reference intervals for the sFLC ratio for those with renal insufficiency.
Summary
On balance, there are several advantages to replacing urinalysis with the sFLC assay. These include increased clinical sensitivity for detection of early-stage disease, patient convenience in submitting a single serum sample rather than two separate specimens, increased use of automation and reduction in subjectivity in reporting of results. However, it is also important to consider the potential increased cost of performing sFLC on all samples submitted for myeloma screening, the importance of using appropriate reference ranges and the need to develop guidelines for interpretation of borderline results. This latter point is particularly important in order that unnecessary referrals are prevented, and should involve close liaison with local hematology teams to ensure that primary care clinicians are given clear guidance for further investigation and referral of their patients.
References
1. Bird JM, Owen RG, D’Sa S, Snowden JA, Pratt G, Ashcroft J, Yong K, Cook G, Feyler S, et al. Guidelines for the diagnosis and management of multiple myeloma 2011. Br J Haematol. 2011; 154(1): 32–75.
2. Brenner H, Gondos A, Pulte D. Expected long-term survival of patients diagnosed with multiple myeloma in 2006–2010. Haematologica 2009; 94(2): 270–275.
3. Rajkumar SV, Kyle RA, Therneau TM, Melton LJ, III, Bradwell AR, Clark RJ, Larson DR, Plevak MF, Dispenzieri A, Katzmann JA. Serum free light chain ratio is an independent risk factor for progression in monoclonal gammopathy of undetermined significance. Blood 2005; 106(3): 812–817.
4. Rajkumar SV, Dimopoulos MA, Palumbo A, Blade J, Merlini G, Mateos MV, Kumar S, Hillengass J, Kastritis E, et al. International Myeloma Working Group updated criteria for the diagnosis of multiple myeloma. Lancet Oncol. 2014; 15(12): e538–548.
5. Kariyawasan CC, Hughes DA, Jayatillake MM, Mehta AB. Multiple myeloma: causes and consequences of delay in diagnosis. QJM 2007; 100(10): 635–640.
6. Howell DA, Smith AG, Jack A, Patmore R, Macleod U, Mironska E, Roman E. Time-to-diagnosis and symptoms of myeloma, lymphomas and leukaemias: a report from the Haematological Malignancy Research Network. BMC Hematol. 2013; 13(1): 9.
7. Elliss-Brookes L, McPhail S, Ives A, Greenslade M, Shelton J, Hiom S, Richards M. Routes to diagnosis for cancer – determining the patient journey using multiple routine data sets. Br J Cancer 2012; 107(8): 1220–1226.
8. Bossuyt X. Separation of serum proteins by automated capillary zone electrophoresis. Clin Chem Lab Med. 2003; 41(6): 762–772.
9. Kaplan IV, Levinson SS. Misleading urinary protein pattern in a patient with hypogammaglobulinemia: effects of mechanical concentration of urine. Clin Chem. 1999; 45(3): 417–419.
10. Bradwell AR, Carr-Smith HD, Mead GP, Tang LX, Showell PJ, Drayson MT, Drew R. Highly sensitive, automated immunoassay for immunoglobulin free light chains in serum and urine. Clin Chem. 2001; 47(4): 673–680.
11. Dispenzieri A, Kyle R, Merlini G, Miguel JS, Ludwig H, Hajek R, Palumbo A, Jagannath S, Blade J, et al. International Myeloma Working Group guidelines for serum-free light chain analysis in multiple myeloma and related disorders. Leukemia 2009; 23(2): 215–224.
12. Myeloma: diagnosis and monitoring. National Institute for Health and Care Excellence (NICE) 2016. (https://www.nice.org.uk/guidance/ng35)
13. Wilson JM, Jungner YG. [Principles and practice of mass screening for disease]. Bol Oficina Sanit Panam. 1968; 65(4): 281–393 (in Spanish).
14. Jagannath S. Value of serum free light chain testing for the diagnosis and monitoring of monoclonal gammopathies in hematology. Clin Lymphoma Myeloma 2007; 7(8): 518–523.
15. McTaggart MP, Lindsay J, Kearney EM. Replacing urine protein electrophoresis with serum free light chain analysis as a first-line test for detecting plasma cell disorders offers increased diagnostic accuracy and potential health benefit to patients. Am J Clin Pathol. 2013; 140(6): 890–897.
The authors
David Baulch* MSc, Beverley Harris MSc, FRCPath
Department of Clinical Biochemistry, Royal United Hospitals Bath NHS Foundation Trust, Bath, UK
*Corresponding author
E-mail: david.baulch@nhs.net
Pharmacogenomics in an acute myelogenous leukemia patient
, /in Featured Articles /by 3wmediaThis article examines the case of a patient who developed toxic levels of voriconazole while taking the antifungal prophylactically as part of her treatment regimen in addition to standard chemotherapy for a leukocyte neoplasm. The usefulness of molecular diagnostic testing as an aid in voriconazole dosing is discussed.
by S. Rezaei, L. Collier and Dr S. Taylor
Case report
The patient was a 14-year-old female who was referred to the emergency department with a 10-day history of generalized bone pain and progressively worsening fatigue. An initial complete blood count (CBC) revealed a white blood cell (WBC) count that was well within the normal range, and only slight anemia and thrombocytopenia. However, because marked neutropenia and elevated numbers of leukemic blasts were noted in the differential, a bone marrow (BM) examination was performed. Marrow aspiration was markedly hypercellular with diffuse clusters of blasts (Fig. 1). Flow cytometry on the aspirate disclosed a significant (50% of total sample) blast population that exhibited CD33, CD13 (partial, dim), CD34 (partial), CD15 (heterogeneous), CD19 (dim), CD10 (dim), HLA-DR, CD64 (partial, dim), CD71 (dim), CD117, CD123, CD58, CD38, cytoplasmic CD79a, CD45 (dim), Tdt, and myeloperoxidase markers. These same markers were exhibited by the circulating blasts in her peripheral blood. The co-expression of B-lymphoid and myeloid antigens prompted an initial diagnosis of biphenotypic acute leukemia. After multiple expert consultations, it was decided to model the patient’s treatment on therapy for acute lymphocytic leukemia (ALL). Thus, the patient received prednisone, vincristine, daunorubicin and PEG asparaginase as induction chemotherapy, with vincristine and daunorubicin administered again 7 days later.
Cytogenetic test results that were returned on day 8, revealed a chromosomal translocation of (8;21)(q22;q22); RUNX1-RUNX1T1, which changed the patient’s diagnosis to an atypical form of acute myelogenous leukemia (AML). Accordingly, the patient’s chemotherapy regimen was changed so that the ALL-type therapy was discontinued and standard AML therapy that included cytarabine, daunorubicin, and etoposide was begun. To address other specific issues, this patient was treated with multiple medications along with her chemotherapy drugs, including Ambien, Bactrim, Benadryl, cefepime, cyproheptadine, hydroxyzine, meropenem, vancomycin, and voriconazole.
On day 16, 8 days after the start of her new pharmacology regimen, the patient began to experience fluctuating confusion and auditory/visual hallucinations. Screening tests revealed no abnormalities that could explain her altered mental status, so attention turned to the medications that she was receiving. All medications that seemed likely to contribute to her neurologic problems were suspended and then reintroduced gradually with no adverse effect. Voriconazole was not suspected of being contributory to her altered mental status, and was not interrupted. This antifungal was first administered to the patient on day 8 of her ordeal, at 200 mg/twice daily. She continued to receive this dose from day 8 onwards, until 4 days after her initial neurological trouble (day 20). At this time, her plasma voriconazole level was determined to be >10.0 μg/mL [normal range (NR): 1.0–6.0 μg/mL]. The patient’s 200 mg twice a day dosing regimen was reduced to 100 mg twice a day. Her plasma concentration of voriconazole was monitored regularly until its level plateaued at 2 μg/mL (Fig. 2).
Pharmacogenomics
Voriconazole is an efficient triazole agent used as an antifungal prophylactic in this patient as she was receiving immunosuppressive chemotherapy. Patients with hematologic malignancies are at high risk of aspergillosis and candidiasis infections, because of the neutropenia that is often caused by their chemotherapy regimens [1–3].
Voriconazole is extensively metabolized in the liver, primarily by CYP2C19 and, to a lesser extent, by CYP2C9 and CYP3A4 liver enzymes. The CYP2C19 genotype is generally accepted as the key determinant in voriconazole clearance [4–6]. Variants of the CYP2C19 genotype have been identified and assigned enzyme activity. Thus the CYP2C19*1 variant is the wild-type variant and exhibits normal enzyme activity. CYP2C19 *2, *3, *4, *5, *6, and *8 isotypes display loss of functionality as they possess little or no activity, and the CYP2C19*17 variant is assigned gain-of-function status because of its robust enzyme activity (Table 1) [7, 8].
Individuals who possess a normal or wild-type drug metabolizing phenotype inherit two copies of the normal CYP2C19 genotype (*1/*1), and are designated as extensive metabolizers (EM). Intermediate metabolizers (IM) have any one of the *2–*8 alleles coupled with a normally functioning (*1) allele. Poor metabolizers (PM) are individuals with an enzyme activity phenotype that is less than optimal, caused by a genotype consisting of loss-of-function alleles (*2–*8/*2–*8 ). Ultrarapid metabolizers (UM) are at the other end of the enzyme activity spectrum, they may either be heterozygous ultrarapid metabolizers with a wild-type allele combined with an gain-of-function allele (*1/*17 genotype), or they may be homozygous ultrarapid metabolizers with only gain-of-function alleles (*17/*17) (Table 1) [7, 8]. The drug metabolizing phenotype of individuals with the gain-of-function allele (*17) combined with a loss-of-function allele (*2–*8) is less clear. There is a certain amount of dissention in the literature as to how these individuals should be classified, that is, various researchers classify them as ultrarapid, extensive, intermediate, or unknown metabolizers [7, 9].
It is intuitive that an individual’s CYP2C19 genotype fundamentally contributes to voriconazole metabolism, elimination, and therefore bioavailability of the drug [4–6].
Systemic exposure to voriconazole is generally higher in individuals with reduced ability to metabolize and eliminate the drug. Trough plasma concentrations of voriconazole have been significantly higher in people possessing PM phenotypes followed by individuals with an IM phenotype, with the lowest bioavailability of the drug detected in individuals with an EM or UM phenotype [4–6, 8]. However, higher trough levels of voriconazole are not universally higher in individuals with reduced CYP2C19 activity [8, 10]. Voriconazole displays expected pharmacokinetic behaviour according to genotype in healthy volunteers, but there is often a marked departure from the customary dose/response relationship in patients. Presumably this deviation from expected pharmacokinetic behaviour is due to drug–drug interactions and/or the pathological circumstances of the patient [5, 6]. Generally, it is expected that disease circumstances or drug side effects that reduce liver enzyme activity (especially of CYP2C19, CYP2C9 and CYP3A4) will decrease metabolism and clearance of voriconazole, and thus increase patient exposure to the drug.
Therapeutic drug monitoring
The United States Food and Drug Administration and the Infectious Diseases Society of America recommend therapeutic drug monitoring (TDM) for patients receiving voriconazole [7]. Numerous studies indicate that voriconazole trough values should be maintained above 1.0 μg/mL for fungal prophylaxis. Moreover, some studies indicate that voriconazole is more efficacious when trough levels are maintained at 2.0 μg/mL or higher [11, 12].
It is important to dose voriconazole accurately, as voriconazole efficacy is dependent on adequate exposure to the drug; however, increased trough levels are associated with numerous severe adverse effects (SAE). Voriconazole has been linked to several adverse events including abnormal liver function tests, gastrointestinal disturbances, rash and vomiting. Neurotoxicity (visual disturbances, hallucinations) is somewhat infrequently observed [1, 2]. Since CYP2C19 is a key metabolizer of voriconazole, it seems reasonable to predict a patient’s drug metabolizing phenotype based on their CYP2C19 genotype, and to use this information to guide dosing. In practice, the drug metabolizing genotype alone is not sufficient to predict the metabolizing phenotype. Confounding variables include the fact that voriconazole has a high propensity for drug–drug interactions, a narrow therapeutic index, it exhibits non-linear pharmacokinetics, and its clearance is affected by circumstances such as patient sex, age, disease state, liver function, obesity and the presence of inflammation [11, 13, 14].
Conclusion
The pharmacodynamic behaviour of voriconazole remains difficult to predict as it displays considerable interpatient and intrapatient variablility. Although TDM for patients receiving voriconazole is recommended, establishing a patient’s pharmacogenomic profile can provide clinicians with valuable information to aid in appropriate voriconazole dosing, especially in the initial stages of therapy. Pharmacogenomic information is likely to contribute to the goal of rapidly attaining a therapeutic concentration while avoiding toxicity. It is possible that our patient has a PM phenotype for voriconazole and that pharmacogenomic testing might have minimized her exposure to toxic levels of voriconazole that arose from standard voriconazole dosing.
References
1. Barreto JN, Beach CL, Wolf RC, Merten JA, Tosh PK, Wilson JW, Hogan WJ, Litzow MR. The incidence of invasive fungal infections in neutropenic patients with acute leukemia and myelodysplastic syndromes receiving primary antifungal prophylaxis with voriconazole. Am J Hematol. 2013; 88(4): 283–288.
2. Mattiuzzi GN, Cortes J, Alvarado G, Verstovsek S, Koller C, Pierce S, Blamble D, Faderl S, Xiao L, Hernandez M, Kantarjian H. Efficacy and safety of intravenous voriconazole and intravenous itraconazole for antifungal prophylaxis in patients with acute myelogenous leukemia or high-risk myelodysplastic syndrome. Support Care Cancer. 2011; 19(1): 19–26.
3. Rüping MJ, Müller C, Vehreschild JJ, Böhme A, Mousset S, Harnischmacher U, Frommolt P, Wassmer G, Drzisga I, Hallek M, Cornely OA. Voriconazole serum concentrations in prophylactically treated acute myelogenous leukaemia patients. Mycoses. 2011; 54(3): 230–233.
4. Ashbee HR, Gilleece MH. Has the era of individualised medicine arrived for antifungals? A review of antifungal pharmacogenomics. Bone Marrow Transplant. 2012;47(7): 881–894.
5. Dolton MJ, McLachlan AJ. Voriconazole pharmacokinetics and exposure-response relationships: assessing the links between exposure, efficacy and toxicity. Int J Antimicrob Agents. 2014;44(3): 183–193.
6. Dolton MJ, Mikus G, Weiss J, Ray JE, McLachlan AJ. Understanding variability with voriconazole using a population pharmacokinetic approach: implications for optimal dosing. J Antimicrob Chemother. 2014;69(6): 1633–1641.
7. Owusu OA1, Egelund EF, Alsultan A, Peloquin CA, Johnson JA. CYP2C19 polymorphisms and therapeutic drug monitoring of voriconazole: are we ready for clinical implementation of pharmacogenomics? Pharmacotherapy. 2014;34(7): 703–718.
8. Moriyama B, Kadri S, Henning SA, Danner RL, Walsh TJ, Penzak SR. Therapeutic drug monitoring and genotypic screening in the clinical use of voriconazole. Curr Fungal Infect Rep. 2015;9(2): 74–87.
9. Swen JJ, Nijenhuis M, de Boer A, Grandia L, Maitland-van der Zee AH, Mulder H, Rongen GA, van Schaik RH, Schalekamp T, Touw DJ, van der Weide J, Wilffert B, Deneer VH, Guchelaar HJ. Pharmacogenetics: from bench to byte-an update of guidelines. Clin Pharmacol Ther. 2011; 89(5): 662–673.
10. Kim SH, Yim DS, Choi SM, Kwon JC, Han S, Lee DG, Park C, Kwon EY, Park SH, Choi JH, Yoo JH. Voriconazole-related severe adverse events: clinical application of therapeutic drug monitoring in Korean patients. Int J Infect Dis. 2011;15(11): 753–758.
11. Davies-Vorbrodt S, Ito JI, Tegtmeier BR, Dadwal SS, Kriengkauykiat J. Voriconazole serum concentrations in obese and overweight immunocompromised patients: a retrospective review. Pharmacotherapy. 2013 Jan;33(1): 22–30.
12. Smith J, Safdar N, Knasinski V, Simmons W, Bhavnani SM, Ambrose PG, Andes D. Voriconazole therapeutic drug monitoring. Antimicrob Agents Chemother. 2006;50(4): 1570–1572.
13. van Wanrooy MJ, Span LF, Rodgers MG, van den Heuvel ER, Uges DR, van der Werf TS, Kosterink JG, Alffenaar JW. Inflammation is associated with voriconazole trough concentrations. Antimicrob Agents Chemother. 2014;58(12): 7098–7101.
14. Brüggemann RJ, Antonius T, Heijst Av, Hoogerbrugge PM, Burger DM, Warris A. Therapeutic drug monitoring of voriconazole in a child with invasive aspergillosis requiring extracorporeal membrane oxygenation. Ther Drug Monit. 2008;30(6): 643–646.
The authors
Sahar Rezaei BS; Laura Collier MLS(ASCP); Sara Taylor* PhD, MLS(ASCP)MB
Tarleton State University, Fort Worth, TX, USA
*Corresponding author
E-mail: sataylor@tarleton.edu