Scientific Lit picture 02


Highly sensitive stool DNA testing of Fusobacterium nucleatum as a marker for detection of colorectal tumours in a Japanese population

Suehiro Y, Sakai K, Nishioka M, Hashimoto S, Takami T, Higaki S, Shindo Y, Hazama S, Oka M, Nagano H, Sakaida I, Yamasaki T. Ann Clin Biochem. 2016; pii: 0004563216643970. [Epub ahead of print]

BACKGROUND: Accumulating evidence shows an over-abundance of Fusobacterium nucleatum in colorectal tumour tissues. Although stool DNA testing of Fusobacterium nucleatum might be a potential marker for the detection of colorectal tumours, the difficulty in detecting Fusobacterium nucleatum in stool by conventional methods prevented further explorations. Therefore, we developed a droplet digital polymerase chain reaction (PCR) assay for detecting Fusobacterium nucleatum in stool and investigated its clinical utility in the management of colorectal tumours in a Japanese population.
METHODS: Feces were collected from 60 healthy subjects (control group) and from 11 patients with colorectal non-advanced adenomas (non-advanced adenoma group), 19 patients with colorectal advanced adenoma/carcinoma in situ (advanced adenoma/carcinoma in situ (CIS) group) and 158 patients with colorectal cancer of stages I to IV (colorectal cancer group). Absolute copy numbers of Fusobacterium nucleatum were measured by droplet digital PCR.
RESULTS: The median copy number of Fusobacterium nucleatum was 17.5 in the control group, 311 in the non-advanced adenoma group, 122 in the advanced adenoma/CIS group, and 317 in the colorectal cancer group. In comparison with that in the control group, the Fusobacterium nucleatum level was significantly higher in the non-advanced adenoma group, the advanced adenoma/CIS group and the colorectal cancer group.
CONCLUSIONS: This study illustrates the potential of stool DNA testing of Fusobacterium nucleatum by droplet digital PCR to detect individuals with colorectal tumours in a Japanese population.

A genome-wide assessment of variations of primary colorectal cancer maintained in metastases

Cai Z, Han S, Li Z, He L, Zhou J, Huang W, Xu Y. Gene 2016; 595(1): 18–24.

Colorectal cancer (CRC) is a highly heterogeneous disease that is the third leading cause of cancer-related deaths worldwide. This study presents a genome-wide assessment of variations in primary colorectal cancer maintained in metastases, even in distant metastases. The purpose of this study was to determine whether intratumor heterogeneity is related to disease progression and metastasis in CRC. The results showed that 882 single nucleotide polymorphism (SNP) associated genes and 473 copy number variant (CNV) associated genes specific to metastasis were found. In addition, 57 SNPs mapped to miRNAs showed significant differences between primary tumours and metastases. Functional annotation of metastasis-specific genes suggested that adhesion and immune regulation may be essential in the development of tumours. Moreover, the locus rs12881063 in the fourteenth chromosome was found to have a high rate of the G/C type in metastases. The rate of the G/C type in nearby lymph node metastases was 66.7%, while the rate of the G/C type in distance lymph node metastases was 83.3%. These results indicate that rs12881063 may be the basis for clinical diagnosis of CRC metastasis.

High tumour mast cell density is associated with longer survival of colon cancer patients

Mehdawi L, Osman J, Topi G, Sjölander A. Acta Oncol. 2016; 55(12): 1434–1442.

BACKGROUND: Inflammatory cells and inflammatory mediators play an important role in colorectal cancer (CRC). Previous studies have shown that CRC patients with increased expression of cysteinyl leukotriene receptor 1 (CysLTR1) have a poorer prognosis, and Cysltr1-/- mice display fewer intestinal polyps. However, the role of mast cells (MCs) in colon cancer progression remains unclear. The aim of the present study was to explore the relevance of MCs in CRC.
MATERIAL AND METHODS: A tissue microarray from 72 CRC patients was stained with MC anti-tryptase and -chymase antibodies. Mouse colon tissue was stained with MC anti-tryptase antibody. Immunohistochemistry was used to identify MCs in patients and mice.
RESULTS: Patient colon cancer tissue had in comparison with normal colon tissue a reduced number of MCs, predominantly of chymase-positive cells. Further analysis revealed that patients with a relative high MCD in their cancer tissues showed significantly longer overall survival compared to those with a low MCD [hazard ratio (HR) 0.539; 95% confidence interval (CI), 0.302–0.961]. Similar results were observed in subgroups of patients with either no distant metastasis (p = 0.004), or <75 years (p = 0.015) at time of diagnosis. Multivariate Cox analysis showed that MCD independently correlated with reduced risk of death in colon cancer patients (HR 0.380; 95% CI 0.202-0.713). Additionally, a negative correlation was found between cytoplasmic CysLTR1 expression and number of MCs. In agreement, in the CAC mouse model, Cysltr1-/- mice showed significantly higher MCs in their polyp/tumor areas compared with wild-type mice.
CONCLUSION: A high MCD in cancer tissue correlated with longer patient survival independently from other risk factors for CRC. The concept that MCs have an anti-tumor effect in CRC is further supported by the findings of a negative correlation with CysLTR1 expression in patients and a high MCD in colon polyps/tumors from CysLTR1-/- mice.

Are hemorrhoids associated with false-positive fecal immunochemical test results?

Kim NH, Park JH, Park DI, Sohn CI, Choi K, Jung YS. Yonsei Med J. 2016; 58(1):150–157.

PURPOSE: False-positive (FP) results of fecal immunochemical tests (FITs) conducted in colorectal cancer (CRC) screening could lead to performing unnecessary colonoscopies. Hemorrhoids are a possible cause of FP FIT results; however, studies on this topic are extremely rare. We investigated whether hemorrhoids are associated with FP FIT results.
MATERIALS AND METHODS: A retrospective study was conducted at a university hospital in Korea from June 2013 to May 2015. Of the 34,547 individuals who underwent FITs, 3946 aged ≥50 years who underwent colonoscopies were analysed. Logistic regression analysis was performed to determine factors associated with FP FIT results.
RESULTS: Among 3946 participants, 704 (17.8%) showed positive FIT results and 1303 (33.0%) had hemorrhoids. Of the 704 participants with positive FIT results, 165 had advanced colorectal neoplasia (ACRN) and 539 had no ACRN (FP results). Of the 1303 participants with hemorrhoids, 291 showed FP results, of whom 81 showed FP results because of hemorrhoids only. Participants with hemorrhoids had a higher rate of FP results than those without hemorrhoids (291/1176, 24.7% vs. 248/2361, 10.5%; p<0.001). Additionally, the participants with hemorrhoids as the only abnormality had a higher rate of FP results than those experiencing no such abnormalities (81/531, 15.3% vs. 38/1173, 3.2%; p<0.001). In multivariate analysis, the presence of hemorrhoids was identified as an independent predictor of FP results (adjusted odds ratio, 2.76; 95% confidence interval, 2.24-3.40; p<0.001).
CONCLUSION: Hemorrhoids are significantly associated with FP FIT results. Their presence seemed to be a non-negligible contributor of FP results in FIT-based CRC screening programmes.