Increased risk of oncogenic human papillomavirus infections and incident high-grade cervical intraepithelial neoplasia among smokers: experience from the Latin American screening study.

BACKGROUND: The purpose of this study was to assess the effect of smoking on the prevalence and incidence of high-risk human papillomavirus (hr-HPV) infection and cervical intraepithelial neoplasia (CIN) in a large sample of Latin American women.
METHODS: The study examines baseline data on over 12,000 women included in the Latin American Screening Study (Brazil and Argentina), and over 1000 women followed-up for a period of 36 months. Three groups were formed: never smokers, current, and past smokers. The prevalence of hr-HPV infection and CIN were compared between the study groups. In the prospective analysis, women were controlled at 6-month intervals to assess the cumulative risk of incident hr-HPV infection, smear abnormalities, and CIN.
RESULTS: A higher prevalence (21.7%) of hr-HPV infection was found among current smokers as compared to never smokers (16.5%) or past smokers (13.5%). Being current smoker was significantly (P <0.01) associated with hr-HPV detection (OR = 1.6; 95% CI = 1.2-2.1). Being a current smoker was a significant predictor of incident hr-HPV during the follow-up [Hazards ratio (HR) = 1.4; 95% CI 1.0-1.9]. For incident CIN2+, being a past smoker (HR = 3.6; 95% CI 1.6-9.8) or current smoker (HR = 3.6; 95% CI 1.5-8.6) were the significant independent predictors. Current and past smokers had a significantly increased risk of incident CIN2+ (P <0.01).
CONCLUSIONS: Smoking increases the risk of contracting hr-HPV infection and modifies the effect of a persistent hr-HPV infection by further increasing the risk of developing CIN2+. It seems that this effect modification persists over several years after smoking cessation.