A 5-year cervical screening interval is as safe and effective for women who test negative for human papillomavirus (HPV) as are 3-year intervals, according to a new ‘real life’ study led by King’s College London (KCL) with researchers from the University of Manchester, and the NHS, on behalf of the HPV pilot steering group.
The study, published in The BMJ, used data from the HPV screening pilot to assess rates of detection of high-grade cervical intraepithelial neoplasia (CIN3+) and of cervical cancer following a negative HPV test. It confirmed that 5-yearly screening prevents as many cancers as screening at 3-year intervals, even in women who are not vaccinated against HPV.
Change to primary HPV testing since 2019
Before 2019, the NHS cervical screening program conducted cytology testing first, testing for HPV only if abnormalities were found. In 2019, following reporting of early results of the HPV pilot by the same researchers, the program in England switched to testing for HPV first, on the grounds that since having HPV infection comes before having abnormal cells, HPV testing would detect more women at risk of cervical cancer.
Following the switch to primary HPV testing, the same screening intervals were retained, meaning 3-yearly screening for those aged 24-49 years and testing every 5 years for women aged 50-64 years, or 3 years if they tested positive. However, the National Screening Committee had recommended that invites should be changed from 3 to 5 years for those in the under-50 age group found not to have high-risk HPV at their routine screening test.
For the latest study, funded by Cancer Research UK, the steering group researchers analyzed details for more than 1.3 million women who had attended screening for two rounds of the HPV screening pilot, the first from 2013 to 2016, with a follow-up to the end of 2019. By this time, the data set had doubled in size from the pilot study, and results had been linked with the national cancer registry.
They confirmed that HPV testing was more accurate than a cytology test, irrespective of whether the HPV test assay was DNA- or mRNA-based. With HPV testing, the risk of subsequent cytological changes more than halved overall. Eligible women under 50 who had a negative HPV screen in the first round had a much lower risk of detection of CIN3+ in the second round, with a rate of 1.21 in 1,000, compared with 4.52 in 1,000 after a negative cytology test.
Data support extension of the testing interval
“The study confirms that women in this age group are much less likely to develop clinically relevant cervical lesions and cervical cancer, 3 years after a negative HPV screen, compared with a negative smear test,” the researchers said.
They suggested that most women do not need to be screened as frequently as the current program allows, and that the data support an extension of the screening intervals, regardless of the test assay used, to 5 years after a negative HPV test in women aged 25-49 years, and even longer for women aged 50 years and older.
However, the screening interval for HPV-positive women who have negative HPV tests at early recall should be kept at 3 years, they said.
“These results are very reassuring,” said lead author Matejka Rebolj, PhD, senior epidemiologist at KCL. “They build on previous research that shows that following the introduction of HPV testing for cervical screening, a 5-year interval is at least as safe as the previous 3-year interval. Changing to 5-yearly screening will mean we can prevent just as many cancers as before, while allowing for fewer screens.”
Michelle Mitchell, Cancer Research UK’s chief executive, said: “This large study shows that offering cervical screening using HPV testing effectively prevents cervical cancer, without having to be screened as often. This builds on findings from years of research showing HPV testing is more accurate at predicting who is at risk of developing cervical cancer compared to the previous way of testing. As changes to the screening [programs] are made, they will be monitored to help ensure that cervical screening is as effective as possible for all who take part.”