Objective: The purpose of this investigation was to assess the association between smoking and clearance of oncogenic human papillomavirus (HPV) infection.
Methods: A prospective cohort study of 346 women aged 18–35 years was conducted. HPV testing was conducted with the Hybrid Capture II (HC II) system and polymerase chain reaction (PCR) with genotyping using the reverse line blot method. At each visit tobacco exposure, reproductive, and sexual histories were assessed. Probability of clearing an oncogenic HPV infection and duration of oncogenic HPV infections by smoking status was assessed.
Results: Regardless of method used, HC II or PCR, ever smokers maintained an HPV infection significantly longer (median duration of 8.5 months vs 10.7 months, never vs ever smokers), and had a lower probability of clearing an oncogenic infection compared with women who never smoked. Smoking duration was significantly associated with HPV clearance, and a dose response was observed. Older age (> 13 years) at smoking initiation was significantly associated with a reduced probability of clearing an oncogenic HPV infection.
Conclusion: This is the first study to demonstrate that smoking promotes early cervical carcinogenic events by increasing duration of oncogenic HPV infections and decreasing probability of clearing oncogenic infections.