HPV test 'does not identify women facing cancer risk'
Adding a test for the human papillomavirus (HPV) to cervical screening does not help doctors identify women at risk of cancer, experts said today.
HPV is a sexually-transmitted infection which causes most cases of cervical cancer.
Around eight out of 10 sexually-active women will contract HPV at some point in their lives.
The infection clears itself up within two years in some 80% of cases but women are at high risk of re-infection.
The NHS has been piloting the idea of routinely adding HPV testing to cervical screening in six laboratories across the UK.
For women whose smear results show “borderline” or mild abnormalities - suggesting cervical cells could develop to cancer at some point in the future - an HPV test has been carried out on their sample.
It is thought that women with mild or borderline test results who have no evidence of high risk HPV infection are highly unlikely to develop cervical cancer. The NHS hopes these women could be spared further invasive tests.
Meanwhile, those women who are carrying HPV could benefit from speedier referrals for further investigation.
However, new research published today says adding the HPV test to smear tests does not help doctors identify which women are at risk of cancer or the best form of follow -up treatment.
The study, funded by the Medical Research Council (MRC), showed that 70% of women testing positive for HPV after a borderline or mild abnormality smear did not develop cancer during a three-year follow-up.
The experts said it was difficult to distinguish between the small minority of women who have minor cell changes which might progress to cancer from the great majority of women who have minor cell changes which will not develop into cancer.
More than 4,000 women with borderline or mild test results were included in the study.
Their samples were all tested for HPV, with 1,755 women (44%) receiving a positive HPV result.
Yet most of these women (1,234 or 70%) did not develop pre-cancerous disease during the trial.
The trial was called Tombola (Trial of Management of Borderline and Other Low-Grade Abnormal Smears).
Dr Maggie Cruickshank, from the Department of Obstetrics and Gynaecology at the University of Aberdeen and one of the authors of the study, said: “It has been suggested that testing for HPV as part of the cervical screening programme could be a useful tool to help doctors pinpoint which women are at risk of cancer.
“But the Tombola trial results show the risk of being diagnosed with cancer following a positive HPV test might be harder to predict.
“Of the women who actually needed treatment for pre-cancerous disease over the course of the study, 91 out of 393 (23%) had a negative HPV test at the start of the trial.
“For younger women, HPV testing after a low grade smear could lead to unnecessary investigations and intervention.”
Julietta Patnick, director of the NHS Cancer Screening Programmes, said the Tombola trial relied on old tests which were less accurate than newer methods.
New tests are carried out using liquid-based cytology.
She said: “We always welcome new data that could help us to improve the Cervical Screening Programme, and will review the results of the Tombola study with interest.
“However, it is unfortunate that the study, which began in 1999, used what is now old screening technology and methodology. With the modern techniques and approaches we use today, HPV triage looks very promising for women whose cytology results indicate borderline changes and mild dyskaryosis (abnormality).
“Recent international studies support the positive effects of HPV triage – it reduces the number of repeat tests and speeds up referral where needed, and can reduce women’s anxiety about their screening results.”
HPV triage is currently being tested in Norwich, Harrow, Manchester, Liverpool, Bristol and Sheffield and will report later this year.
Around six out of 100 women who have a smear test receive a borderline or mild abnormality result.
