Testing for human papillomavirus (HPV), the cause of most cervical cancers, is more sensitive than the results of conventional cervical tissue analysis, or Pap test, for the detection of cancer, according to the results of an Italian study published in the Journal of the National Cancer Institute. However, this is limited by the fact that HPV infections often resolve among women younger than 35 years of age.
Dr Guglielmo Ronco, from Centro per la Prevenzione Oncologica in Turin, and his associates compared the results of Pap tests with Pap tests plus HPV testing. Next, the researchers randomly assigned more than 49,000 women to Pap tests or HPV testing alone.
Women between the ages of 35 and 60 years old were referred for additional more invasive testing if they were HPV positive, Ronco told Reuters Health. When they pooled the results of the two phases, HPV testing was clearly more sensitive than Pap testing - HPV testing detected more than three high-grade lesions while Pap testing detected only two. The increase in the number of more invasive tests needed to detect a high-grade lesion was limited.
However, women between the ages of 25 and 34 years old who tested HPV-positive were evaluated differently. During the first phase, the women were referred for more invasive testing only if the Pap tests were also abnormal. Those with normal Pap results had the test repeated after one year.
In the second phase, all of the HPV-positive women were directly referred for more invasive testing. With this approach, HPV testing detected over three times more high-grade lesions than did Pap tests, suggesting that most of the tissue irregularities in the younger women will regress spontaneously.
The authors propose that direct referral of younger women with positive HPV test results to invasive testing may represent over-treatment.
Longer follow-up is required before HPV testing can be recommended as a substitute for conventional Pap tests in routine practice, Ronco concluded. – (Karla Gale/Reuters Health)
SOURCE: Journal of the National Cancer Institute, April 2, 2008.
Human Papillomavirus Centre
Cervical Cancer Centre