Smoking and infectious agents and risk of in situ cervical cancer in Sydney, Australia

In a study of 116 in situ cervical cancer patients and 193 matched community controls in Sydney, Australia, smoking was found to be a major risk factor. Current smokers had a adjusted relative risk RR] of 4.5 compared to nonsmokers 95% confidence interval (CI) 2.2-9.1] and exsmokers a RR of 1.3 95% CI 0.6-3.0]. There was a stepwise dose-response relationship between risk and number of cigarettes smoked (30+ cigarettes/day, RR = 5.1, 95% CI 1.5-17.3); this dose-response relationship was more marked among current smokers. Years of cigarette smoking was not consistently related to risk. Exposures to herpes simplex virus type 2 and cytomegalovirus as measured by antibody prevalence were unrelated to risk (RR = 1.1 for both measures). However, cases appeared to have more exposure than controls to herpes simplex virus type 1 (RR = 2.3, 95% CI 1.1-4.4).