No Increase in Breast Cancer Risk in Japanese Women Taking Oral Contraceptives: a Case-Control Study Investigating Reproductive, Menstrual and Familial Risk Factors for Breast Cancer

摘要: Background: Low-dose oral contraceptives (OC) were approved by the Japanese Ministry of Health, Labor and Welfare in 1999, yet despite their contraceptive non-contraceptive health benefits, only 5% target population use them. Fear increased cancer risk, particularly breast cancer, is one reason for this. Due to low OC uptake screening participation, a paucity data available on risk women. The present study investigated as well menstrual, reproductive family factors. Materials Methods: This was clinic-based case-control women aged 20-69yrs who had undergone between January 2007 December 2013 central Tokyo. In all, 28.8% participants experience with use. Cases 155 pathologically confirmed diagnosis cancer. Controls remaining 12,333 Results: Increased age significant factor (p<0.001). A lower found premenopausal presently taking compared never users (OR 0.45; 95% CI 0.22-0.90) after adjusting age, parity feeding, history Conclusions: rather than greater effect risk. may be decreased use, but further long-term prospective studies are necessary.