HPV and Smoking Synergistic in Raising Cervical Cancer Risk

NEW YORK NOV 17, 2006 (Reuters Health) - Women who smoke and carry human papillomavirus type 16 (HPV-16) are at greater risk for cervical cancer in situ (CIS) than their peers with only one of the two factors, according to a report in Cancer Epidemiology, Biomarkers & Prevention for November.

The risk of cancer was particular high in smokers with high loads of HPV-16, lead author Dr. Anthony S. Gunnell, from the Karolinska Institute in Stockholm, and colleagues note.

"Our initial analyses centered on whether smoking was an independent risk factor for cervical cancer," Dr. Gunnell said in a statement. "Clearly, both exposures need to be present at the same time for there to be an interaction."

The new findings are based on a comparison of HPV-16 status (in archival cervical smears) and smoking among 375 women with CIS and 363 controls.

Current smokers positive for HPV-16 were 14.4-fold times more likely to have CIS than HPV-negative current smokers. In nonsmokers, HPV-16 positivity only increased the risk of cancer by 5.6-fold.

Current smoking coupled with a high HPV-16 load raised the risk of CIS by 27-fold compared with HPV-16-negative smokers. In nonsmokers, the elevated risk with a high HPV-16 load was just 5.9-fold.

"We were surprised to see this dramatically increased risk among women with high viral loads who smoked," Dr. Gunnell commented.

A significant correlation between smoking duration and HPV-16 positivity was noted, the researchers state.

"Our study would imply a synergistic action between HPV and smoking that would greatly increase the likelihood of women developing cervical cancer if they are HPV-positive smokers. This would put them in a risk group worthy of careful monitoring," Dr. Gunnell emphasized.

SOURCE:

• Cancer Epidemiol Biomarkers Prev 2006.