HPV Tests Predict Cervical Cancer Risk

The best initial cervical-cancer screening tool for younger women is still the traditional Papanicolaou (Pap) smear. However, a recent study found that for older women (age 40 and older), a test for human papillomavirus (HPV) is a much-more-effective way to screen for potential cancer.

Professor Susanne Kjaer of the Institute of Cancer Epidemiology, Danish Cancer Society (Copenhagen, Denmark), and colleagues studied 8,656 younger women (22–32 years old) and 1,578 older women (40–50 years old) who were followed over a 10-year period for development of cervical neoplasia (cytology and/or histology) through the Danish Pathology Data Bank. The majority of women in both groups had both a negative Pap smear and a negative HPV test at the beginning of the study. The study appeared in the November 2006 issue of Cancer Research.

The 10-year absolute risk of cancer, or grade three cervical intraepithelial neoplasia (CIN3), was about 13.6% in the younger women with a baseline positive HPV test, and 21.2% in the older women who were HPV-positive. By contrast, among women who were HPV-negative at baseline, those in the younger cohort had a 10-year absolute risk of 4.1% and those in the older group had a risk of 1.7%. However, among those who were positive for HPV--17% in the younger women and 3.6% in the older women--the risk of later cervical abnormalities, up to and including cancer, was markedly higher than among those who were negative on both tests.

The risks were probably lower in the younger women even though they had a higher prevalence of HPV infection, noted Professor Kjaer, because many such infections were transient, while in older women they were persistent and caused greater changes at the cellular level. The HPV test in cytologically negative women is substantially predictive of high-grade CIN and suggests that hybrid capture 2 (HC2) testing can help stratify women into different risk categories. HC2 is a test for detection of 13 oncogenic HPV DNA types.

"This shows that the HPV test was better than a Pap smear at predicting worrisome changes in the cervix over time,” because Pap smears were negative in all the women in the study, said Professor Kjaer. One implication is that the HPV test should be routinely used in older women, with or without a Pap smear. "Based on these results, we feel that an HPV test would benefit older women, whether or not that test is used in conjunction with Pap smears, or used by itself as an initial screen.”



Related Links:
Danish Cancer Society