Cervical screening has little impact on cancer rates in young women

NEW YORK (Reuters Health) - New research suggests that cervical screening with Pap smears in women between 20 and 24 years of age does not affect the rate of invasive cervical cancer before 30 years of age. By contrast, in older women, cervical screening is associated with a marked reduction in rates of invasive disease and associated mortality, the results indicate.

In another study, researchers show that the short-term persistence of carcinogenic human papillomavirus, particularly HPV-16, is a strong predictor of cervical intraepithelial neoplasia grade II+ (CIN2+) in subsequent years. The results of both studies are reported in the July 29th Online First issue of BMJ.

To investigate the effectiveness of cervical screening with age, Dr. Peter Sasieni, from Queen Mary, University of London, and colleagues analyzed data from 4012 women, 20 to 69 years of age, with invasive cervical cancer and 7889 matched control subjects without cancer.

As noted, screening for women in their early 20s did not reduce cervical cancer rates by age 30. In contrast, in women between 40 and 64 years, screening cut the risks of cancer by 60% and 80%, respectively. Screening older women was particularly effective in preventing advanced stage malignancies.

In the second study, Dr. Philip E. Castle, from the National Cancer Institute at the National Institutes of Health, Bethesda, Maryland, and colleagues assessed the predictive value of serial HPV testing in 2282 sexually active women. Testing was performed at enrollment and roughly 1 year later.

Subjects who tested positive for carcinogenic HPV at baseline and 1 year had a CIN2+ rate of 17.0%. The rates among women who did not test positive at either point or tested positive at only one point were significantly lower, never exceeding 3.4%.

For subjects with persistent HPV-16 infection, the 3-year cumulative incidence of CIN2+ was 40.8%, the report indicates. Findings similar to the 3-year test point were obtained after 5 years.

Editorialists Drs. Guglielmo Ronco and Dr. Nereo Segnan of the Centre for Cancer Prevention, Turin, along with Dr. Marc Arbyn of the Scientific Institute of Public Health, Brussels, comment on both studies.

"The question is whether to screen younger women, and if so, how? In many developed countries, the low incidence of invasive cervical cancer and the lack of effectiveness of screening in young women indicate that screening should not start before the age of 25," they note. "For women aged 25-34, screening with HPV testing alone is much more sensitive than screening with cytology, but it is also less specific."

Copyright © 2009 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.