The role of smoking and other risk factors for cervical neoplasia was investigated in a population-based case-control study of 586 women with histologically verified cervical squamous-cell carcinoma in situ (CIS), and 59 women with invasive squamous-cell cervical cancer from Copenhagen. Controls were randomly selected from the general female population using the computerized Danish Central Population Register. After adjustment for a variety of confounding variables, which were all significantly associated with CIS risk and included age, number of partners, proportion of sexually active life without barrier contraceptive use, years with intra-uterine devices, number of births, and age at first episode of genital warts (as a proxy measure for human papillomavirus exposure), current cigarette smoking was found to be significantly associated with CIS [adjusted relative risk (RR) = 2.4; 95% confidence interval (CI): 1.7-3.4]. Ex-smokers had a lower, but still significantly increased risk (RR = 1.6; 95% CI: 1.0-2.7). A dose-response relationship was present, especially for number of cigarettes smoked per day. In contrast, the crude estimates showed a weak association between invasive cervical cancer and smoking, which however disappeared after confounder control. The results of the present study support the hypothesis implicating smoking as a risk factor for CIS.
PIP: The role of smoking and other risk factors for cervical neoplasia was investigated in a population-based case-control study of 586 women with histologically verified cervical squamous-cell carcinoma in situ (CIS), and 59 women with invasive squamous-cell cervical cancer from Copenhagen. Controls were randomly selected from the general female population using the computerized Danish Central Population Register. After adjustment for a variety of confounding variables, which were all significantly associated with CIS risk and included age, number of partners, proportion of sexually active years without barrier contraceptive use, years with IUDs, number of births, and age at first episode of genital warts (as a proxy measure for human papillomavirus exposure), current cigarette smoking was found to be significantly associated with CIS [adjusted relative risk (RR) = 2.4; 95% confidence interval (CI): 1.7-3.4]. Ex-smokers had a lower, but still significantly increased risk (RR = 1.6; 95% CI: 1.0-2.7). A dose-response relationship was present, especially for number of cigarettes smoked per day. In contrast, the crude estimates showed a weak association between invasive cervical cancer and smoking, which however disappeared after confounder control. The results of the present study support the hypothesis implicating smoking as a risk factor for CIS.