CASE-CONTROL STUDY OF RISK-FACTORS FOR CERVICAL SQUAMOUS-CELL NEOPLASIA IN DENMARK .4. ROLE OF SMOKING-HABITS

The role of smoking and other risk factors for cervical neoplasia was investigated in a population-based case-control study of 586 women wit h histologically verified cervical squamous-cell carcinoma in sitre (C IS), and 59 women with invasive squamous-celI cervical cancer from Cop enhagen. Controls were randomly selected from the general female popul ation using the computerized Danish Central Population Register. After adjustment for a variety of confounding variables, which were all sig nificantly associated with CIS risk and included age, number of partne rs, proportion of sexually active life without barrier contraceptive u se, years with intra-uterine devices, number of births, and age at fir st episode of genital warts (as a proxy measure for human papillomavir us 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 significan tly increased risk (RR = 1.6; 95% CI: 1.0-2.7). A dose-response relati onship was present, especially for number of cigarettes smoked per day . In contrast, the crude estimates showed a weak association between i nvasive cervical cancer and smoking, which however disappeared after c onfounder control. The results of the present study support the hypoth esis implicating smoking as a risk factor for CIS.