Objective: To examine the effect of smoking on the incidence of low- and high-grade cervical intraepithelial neoplasia (CIN) in women with a baseline Pap smear of atypical squamous cells (ASC) or a low-grade squamous intraepithelial lesion (LSIL).
Design: Prospective study in which a cohort of women with normal colposcopy and ASC/LSIL at baseline were followed at 6-month intervals of up to 36 months. Women were grouped in post-hoc analysis according to their smoking behavior: never (or past) smokers and current smokers.
Setting: This report was based on data from the Latin American Screening Study, conducted in Sao Paulo, Campinas, Porto Alegre (Brazil) and Buenos Aires (Argentina).
Population: A subset of 150 women derived from a cohort of 1,011 women.
Methods: Multivariate Cox analysis and Kaplan-Meier curves were used.
Main outcome measures: Low- and high-grade CIN during follow-up.
Results: The only factor related to an increased risk of developing CIN was the positive high-risk (hr) HPV status (hazard ratio (HR) = 3.42; 95% CI: 1.11-9.43). A total of 21 cases of incident CIN were detected during follow-up. Of these, 11 appeared in the group of 67 smokers and 10 among the 83 non-smoker women (log-rank, p=0.33). Smoking status was not associated with the risk of developing CIN (HR = 0.73; 95% CI: 0.40-1.33). However, when restricting the analysis to high-grade CIN only (11 cases), the probability of developing the disease was significantly higher among smokers (p=0.04).
Conclusions: Smoking contributes additional risk for developing high-grade CIN in women with ASC or LSIL cytology but normal colposcopy.