Smoking may slow clearance of cervical infection

Women who smoke cigarettes may have a tougher time clearing a virus linked to cervical cancer from their bodies.

At least 70 percent of sexually active women will become infected with human papillomavirus (HPV) at some point in their lives, Dr. Jill Koshiol of the National Cancer Institute in Bethesda, Maryland and colleagues explain in the American Journal of Epidemiology.

HPV infection is temporary most of the time, but longer-term infection with high-risk strains of the virus is a key factor in the development of precancerous changes in the cervix and of cervical cancer.

Smoking has been linked to cervical cancer, Koshiol and her team add. To investigate whether cigarette smoking might affect the time it takes to clear an HPV infection, the researchers looked at a group of 801 women from four large US cities participating in a study of HIV, 522 of whom were HIV-positive. The women were followed for an average of about four years.

Among the HIV-negative women, the researchers found, it took slightly longer for women who had ever smoked to clear HPV virus overall, and it took them significantly longer to clear higher risk strains of the virus.

"Smoking may increase a woman's likelihood of developing a persistent HPV infection by causing immunosuppression in the cervix," Koshiol and her colleagues write.

The study was limited by the fact that just 13.9 percent of all participants had never smoked, the team adds. Further research is needed, they conclude, to confirm that the relationship between smoking and HPV clearance varies with the virus strain.

SOURCE: American Journal of Epidemiology, July 15, 2006.