Alison Pic

Cervical cancer screening tests: HPV testing will replace Pap smear

In the 1980s, cervical screening tests were introduced for the detection of abnormal cervical cells (the cytology-based Pap smear test). Since then there has been a reduction in the number of cervical cancer cases by about 7% each year. Under current guidelines in the UK, women are offered 12 tests per lifetime, with frequency based on age: every 3 years for 25–49-year-olds, every 5 years for 50–64-year-olds, and only in certain circumstances for women over 65.
We have been aware for some time that certain high-risk types of human papillomavirus (HPV) are the causative agents of virtually all cases of cervical cancer and a new cervical test procedure is set to be introduced in England by 2019 that will first test samples for HPV and then only check for abnormal cells if the virus is found. Primary HPV testing has a higher sensitivity, lower false-negative rate and is more cost-effective than cytology, thus allowing further resources and cytology-based tests to be reserved for the closer follow-up of women who test positive for high-risk HPV types.
This change is being introduced at around the same time that the first women to be vaccinated against HPV are about to enter the screening system. In the UK, vaccination of girls against HPV began in 2008 using Gardasil, which protects against HPV 16 and 18 as well as 6 and 11 (responsible for approximately 90% of cases of benign genital warts) and dramatically reduces the risk of cervical cancer. Gardasil-9 offers protection against nine HPV types, adding 31, 33, 45, 52 and 58 to the four mentioned above, but is currently only available privately in the UK. Recent research by Landy et al. in the International Journal of Cancer (2017; doi: 10.1002/ijc.31094) suggests that with the use of primary HPV testing, the screening programme should be personalized based on vaccination status, with perhaps as few as two lifetime tests needed for women who have received the nonavalent vaccine, three for the quadrivalent vaccine and seven for unvaccinated women.
However, the researchers also note that with many fewer tests, it is crucial that participation in screening is high; however, recent figures revealed that less than three-quarters of women take up screening invitations. Perhaps this would improve if the method of sample collection was changed from a cervical smear to a urine-based HPV test.