Browsing by Author "Azam, Shadi"

Background: Oral contraceptive (OC) use may increase the risk of specific cancers and mortality. The aims of this study were to investigate the association between OC use and its duration with the risk of breast cancer, to examine the overall mortality associated with OC use and its duration, and finally to identify sociodemographic characteristics of OC use. Methods: Data are derived from the Older Finnish Twin cohort consisted of monozygotic and same-sexed dizygotic twin pairs born before 1958. We included N = 9,607 Finnish twin women aged 18 – 49 years old with information on OC use and other covariates. The information on OC use, reproductive, and lifestyle factors was collected using a mailed questionnaire. The information on breast cancer incidence was obtained from the Finnish Cancer Registry and the data on mortality was collected from the national Population Information System and Statistics Finland. We used Cox proportional hazards regression to estimate the association between OC use and its duration with risk of breast cancer and overall mortality while controlling for potential confounders. Also, we used logistic regression to identify sociodemographic characteristics of OC use. All tests of statistical significance were two-sided. Results: A total of 758 women developed breast cancer during median follow-up of 42.6 years. Women who ever used OC had 20% greater risk of developing breast cancer than women who never used (HR =1.20, 95% CI = 1.02 to 1.40, P = 0.02). Women who used OC for more than 5 years had greater risk of developing the disease than those who used OC for less than 2 years (HR = 1.11, 95% CI = 0.85 to 1.46), however, the results did not reach the statistical significance. Mortality did not significantly different between women who had ever used OC with those who had not used OC while controlling for potential confounders. Current smokers and women who consumed alcohol more than 10 gram/day had the highest odds of ever using OC. Conclusion: Our results suggest that OC use slightly increases the risk of breast cancer, however, no evidence from this study indicates that OC use adversely affect long-term risk for mortality.