The findings therefore support a switch to HPV screening across England and provide reassurance that screening intervals could be safely extended to at least five years, without increasing the risk of potentially life threatening disease.
At present, 2,500 cases of cervical cancer are diagnosed each year in England, with a quarter diagnosed after a ‘normal’ smear test result.
Clinical trials show that HR-HPV screening leads to earlier detection of cervical lesions than liquid-based cytology or LBC (“smear”) testing. As such, NHS England and Public Health England are working towards a national roll-out of HPV screening by the end of 2019.
To ensure these trial results would work in the ‘real world’ a large pilot study of routine HPV and LBC testing was carried out in six NHS laboratories across England.
A team of researchers, including King’s College London analysed results from this pilot, which included 578,547 women aged 24-64 years undergoing routine cervical screening (32% HR-HPV; 68% LBC) between May 2013 and December 2014, followed up until May 2017.
Women were immediately referred for further testing (colposcopy) if their HR-HPV test was positive and cervical lesions were found.
HR-HPV positive women with no cervical lesions were asked to return in 12 months for another test (early recall), and if HR-HPV persisted without abnormal cells, were recalled again at 24 months. Reassuringly, 80% of women attended these early recall appointments.
After taking account of factors that might have affected the results, the researchers compared levels of cervical lesions (CIN) picked up by the two screening tests.
CIN is divided into grades - CIN1, 2+ or 3+. The higher the number, the more of the cervix is affected. They found that HR-HPV screening detected substantially more CIN than LBC testing (50% more CIN2+, 40% more CIN3+ and 30% more cervical cancer). What’s more, a quarter of the CIN2+ was detected after early recall in women with no cervical lesions.
The increased sensitivity of HR-HPV screening is also reflected in the remarkably low detection of CIN2+ amongst HR-HPV negative women when rescreened at three years, compared with LBC negative women.
Lead author Matejka Rebolj, Senior Epidemiologist from King’s said: “Our study confirms that that HR-HPV screening is practical on a large scale and confers greater sensitivity then current smear testing. This means that the women whose lives can be saved through screening will be better served by the new test. At the same time, women with negative test results will not need to be screened as often as they are now.”
Professor Anne Mackie, Director of Programmes, UK National Screening Committee, said: “This PHE funded pilot showed that primary HPV screening could be successfully introduced into the English Cervical Screening Programme and was acceptable to women.
“Its findings support evidence from randomised trials, suggesting that there will be a 20% reduction, around 400 to 500 cases a year, in cervical cancer diagnosis, once primary HPV screening is rolled out nationally in England.
“These positive results provided the independent expert screening committee (UK NSC) with further evidence to support the recommendation that the HPV test should replace cytology as the primary test performed on all screening samples, as it was shown to identify more women at risk of developing cervical cancer.”
The full paper is available online.