title: Smoking is an independent risk factor for oncogenic human papillomavirus (HPV) infections but not for high-grade CIN.
abstract: BACKGROUND
  Recent evidence implicates smoking as a risk factor for cervical cancer (CC), but the confounding from high-risk human papillomavirus (HPV) infections is not clear.
  
  
  OBJECTIVE
  To analyse the role of smoking as an independent predictor of CIN2+ and HR-HPV infections in a population-based prospective (NIS, New Independent States of former Soviet Union) cohort study.
  
  
  METHODS
  A cohort of 3,187 women was stratified into three groups according to their smoking status: (i) women who never smoked; (ii) those smoking in the past; and (iii) women who are current smokers. These groups were analysed for predictors of (a) HR-HPV; (b) high-grade CIN, and (c) outcome of HR-HPV infections and cytological abnormalities during prospective follow-up (n = 854).
  
  
  RESULTS
  The three groups were significantly different in all major indicators or risk sexual behaviour (or history) implicating strong confounding. There was no increase in HSIL/LSIL/ASC-US cytology or CIN1+/CIN2+/CIN3+ among current smokers. Only few predictors of HR-HPV and CIN2+ were common to all three groups, indicating strong interference of the smoking status. There was no difference in outcomes of cervical disease or HR-HPV infections between the three groups. In multivariate model, being current smoker was one of the five independent predictors of HR-HPV (P = 0.014), with adjusted OR = 1.52 (95%CI 1.09-2.14). In addition to age, HR-HPV was the only independent predictor of CIN2+ in multivariate model (OR = 14.8; 95%CI 1.72-127.31).
  
  
  CONCLUSIONS
  These data indicate that cigarette smoking is not an independent risk factor of CIN2+, but the increased risk ascribed to smoking is mediated by acquisition of HR-HPV, of which current smoking was an independent predictor in multivariate model.
authors.affiliation: Department of Oncology and Radiotherapy, Turku University Hospital, Savitehtaankatu 1, Turku, 20521, Finland. kari.syrjanen@tyks.fi
authors.forename: Kari
authors.initials: K
authors.lastname: Syrjänen
authors.forename: Irena
authors.initials: I
authors.lastname: Shabalova
authors.forename: Nicolay
authors.initials: N
authors.lastname: Petrovichev
authors.forename: Vladimir
authors.initials: V
authors.lastname: Kozachenko
authors.forename: Tatjana
authors.initials: T
authors.lastname: Zakharova
authors.forename: Julia
authors.initials: J
authors.lastname: Pajanidi
authors.forename: Jurij
authors.initials: J
authors.lastname: Podistov
authors.forename: Galina
authors.initials: G
authors.lastname: Chemeris
authors.forename: Larisa
authors.initials: L
authors.lastname: Sozaeva
authors.forename: Elena
authors.initials: E
authors.lastname: Lipova
authors.forename: Irena
authors.initials: I
authors.lastname: Tsidaeva
authors.forename: Olga
authors.initials: O
authors.lastname: Ivanchenko
authors.forename: Alla
authors.initials: A
authors.lastname: Pshepurko
authors.forename: Sergej
authors.initials: S
authors.lastname: Zakharenko
authors.forename: Raisa
authors.initials: R
authors.lastname: Nerovjna
authors.forename: Ludmila
authors.initials: L
authors.lastname: Kljukina
authors.forename: Oksana
authors.initials: O
authors.lastname: Erokhina
authors.forename: Marina
authors.initials: M
authors.lastname: Branovskaja
authors.forename: Maritta
authors.initials: M
authors.lastname: Nikitina
authors.forename: Valerija
authors.initials: V
authors.lastname: Grunberga
authors.forename: Alexandr
authors.initials: A
authors.lastname: Grunberg
authors.forename: Anna
authors.initials: A
authors.lastname: Juschenko
authors.forename: Rosa
authors.initials: R
authors.lastname: Santopietro
authors.forename: Marcella
authors.initials: M
authors.lastname: Cintorino
authors.forename: Piero
authors.initials: P
authors.lastname: Tosi
authors.forename: Stina
authors.initials: S
authors.lastname: Syrjänen
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D030361:Papillomavirus Infections / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D011446:Prospective Studies; D012307:Risk Factors; D012426:Russia / Q000453:epidemiology; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology; D002583:Uterine Cervical Neoplasms / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D002578:Uterine Cervical Dysplasia / Q000209:etiology*