Smoking is an independent risk factor for oncogenic human papillomavirus (HPV) infections but not for high-grade CIN.
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.
Syrjänen
Kari
K
Department of Oncology and Radiotherapy, Turku University Hospital, Savitehtaankatu 1, Turku, 20521, Finland. kari.syrjanen@tyks.fi
Shabalova
Irena
I
Petrovichev
Nicolay
N
Kozachenko
Vladimir
V
Zakharova
Tatjana
T
Pajanidi
Julia
J
Podistov
Jurij
J
Chemeris
Galina
G
Sozaeva
Larisa
L
Lipova
Elena
E
Tsidaeva
Irena
I
Ivanchenko
Olga
O
Pshepurko
Alla
A
Zakharenko
Sergej
S
Nerovjna
Raisa
R
Kljukina
Ludmila
L
Erokhina
Oksana
O
Branovskaja
Marina
M
Nikitina
Maritta
M
Grunberga
Valerija
V
Grunberg
Alexandr
A
Juschenko
Anna
A
Santopietro
Rosa
R
Cintorino
Marcella
M
Tosi
Piero
P
Syrjänen
Stina
S
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*