Asian Pacific Journal of Cancer Prevention : APJCP, 16(9), 3685-3690, 2015
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
Low-dose oral contraceptives (OC) were approved by the Japanese Ministry of Health, Labor and Welfare in 1999, yet despite their contraceptive and non-contraceptive health benefits, only 5% of the target population use them. Fear of increased cancer risk, particularly breast cancer, is one reason for this. Due to low OC uptake and low screening participation, a paucity of data is available on the risk of OC use and breast cancer in Japanese women. The present study investigated OC use and breast cancer risk, as well as menstrual, reproductive and family factors.
Materials and Methods
This was a clinic-based case-control study of women aged 20-69yrs who had undergone breast screening between January 2007 and December 2013 in central Tokyo. In all, 28.8% of the participants had experience with OC use. Cases were 155 women with a pathologically confirmed diagnosis of breast cancer. Controls were the remaining 12,333 women.
Results
Increased age was a significant risk factor for breast cancer (p<0.001). A lower risk was found in premenopausal women presently taking OC compared to never users (OR 0.45; 95% CI 0.22-0.90) after adjusting for age, parity and breast feeding, and a family history of breast cancer.
Conclusions
Increased age rather than OC use had a greater effect on breast cancer risk. This risk may be decreased in premenopausal women with OC use, but further long-term prospective studies are necessary.
oral contraceptives breast cancer risk Japanese women, OC use breast cancer case-control study Japan, low dose oral contraceptives cancer risk premenopausal women, reproductive factors breast cancer risk Asian population, oral contraceptive protective effect breast cancer premenopausal, menstrual and familial risk factors breast cancer screening, oral contraceptive uptake Japan fear cancer risk, parity breastfeeding family history breast cancer oral contraceptive adjustment, age as risk factor breast cancer vs oral contraceptive use, contraceptive health benefits versus cancer risk perception
PMID 25987022 25987022 DOI 10.7314/apjcp.2015.16.9.3685 10.7314/apjcp.2015.16.9.3685
Cite this article
Ichida, M., Kataoka, A., Tsushima, R., & Taguchi, T. (2015). 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. Asian Pacific journal of cancer prevention : APJCP, 16(9), 3685-3690. https://doi.org/10.7314/apjcp.2015.16.9.3685
Ichida M, Kataoka A, Tsushima R, Taguchi T. 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. Asian Pac J Cancer Prev. 2015;16(9):3685-3690. doi:10.7314/apjcp.2015.16.9.3685
Ichida, M., et al. "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." Asian Pacific journal of cancer prevention : APJCP, vol. 16, no. 9, 2015, pp. 3685-3690.
Keywords
Contraceptives, Oral
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