The long term findings of a study carried out at Hammersmith hospital reveal that testing for Human Papilloma Virus (HPV) can be twice as effective at protecting women from developing cervical abnormalities as smear testing. Results of the research -- led by Professor Jack Cuzick of Barts and The London School of Medicine and Dentistry - are published 15 May 2008 in the International Journal of Cancer.
Nearly 3,000 women aged 35+ were recruited into the study between April 1994 and September 1997. They were asked to participate in a study in which HPV testing would be performed in addition to cytology (smear test) whilst attending their GP practice (40 practices were involved in the trial) for a routine cervical smear. Women who had previously been treated for cervical intra-epithelial neoplasia (CIN) -- changes to cells in the cervix that can develop into cancer -- or had experienced any cervical abnormality within the previous 3 years, were excluded from the study.
All women tested were followed up passively using data from the national computerised system that records all smears and their results -- the Open-Exeter system. Women with a smear history indicating the need for colposcopy -- a more thorough examination of the cervix -- were investigated further to determine whether the colposcopy and biopsy were performed, and what the resultant outcome was. Passive follow-up was complete for all women by early 2005.
Results showed that the risk of developing cervical abnormalities at 1, 5, and 9 years after a normal smear test was 0.33 per cent, 0.83 per cent, and 2.20 per cent respectively, with those odds significantly reduced after a negative HPV test - 0.19 per cent, 0.42 per cent, and 1.88 per cent.
Professor Jack Cuzick said: "Not only does the research confirm that HPV testing detects more disease at each smear, it shows that this approach offers women excellent protection from cervical abnormalities for at least 6 years after a negative test, compared to protection from a normal smear test which begins to wane after about 3 years. This suggests that the screening interval can be safely extended to at least 6 years with HPV testing. These data provide more support for replacing screening based on abnormal cells, with a more sensitive test based on screening for the human papillomavirus."
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