Background: Breast and ovarian cancers are predominant female cancers with increasing prevalence. The purpose of this study was to estimate the population attributable risks (PARs) of breast and ovarian cancer occurrence based on the relative risks (RRs) of modifiable reproductive factors and population-specific exposure prevalence. Methods: The PAR was calculated by using the 1990 standardized prevalence rates, the 2010 national cancer incidence with a 20 year lag period, the meta-analyzed RRs from studies conducted in the Korean population for breast cancer, and the meta-analyzed RRs from a Korean epithelial ovarian cancer study and a prior meta-analysis, and ovarian cancer cohort results up to 2012. For oral contraceptive and hormone replacement therapy use, we did not consider lag period. Results: The summary PARs for modifiable reproductive factors were 16.7 % (95 % CI 15.8-17.6) for breast cancer (2404 cases) and 81.9 % (95 % CI 55.0-100.0) for ovarian cancer (1579 cases). The modifiable reproductive factors included pregnancy/age at first birth (8.0 %), total period of breastfeeding (3.1 %), oral contraceptive use (5.3 %), and hormone replacement therapy use (0.3 %) for breast cancer and included breastfeeding experience (2.9 %), pregnancy (1.2 %), tubal ligation (24.5 %), and oral contraceptive use (53.3 %) for ovarian cancer. Conclusions: Despite inherent uncertainties in the risk factors for breast and ovarian cancers, we suggest that appropriate long-term control of modifiable reproductive factors could reduce breast and ovarian cancer incidences and their related burdens by 16.7 % and 81.9 %, respectively.
Bibliographical noteFunding Information:
The study is part of a systematic analysis of attributable causes of cancer in Korea conducted by working group experts in collaboration with the National Cancer Center, Korea and the International Agency for Research on Cancer. This study was supported by a research grant from the National Cancer Center, Korea (NCC-0710160) and a grant from the National R&D Program for Cancer Control, Ministry for Health, Welfare and Family affairs, Republic of Korea (1420190). We thank Mathieu Boniol from the International Prevention Research Institute, Lyon, France and Paolo Boffetta from the Tisch Cancer Institute, Mount Sinai School of Medicine, New York, United States of America for their help while they were working at the International Agency for Research on Cancer, Lyon, France.
© 2016 Park et al.
All Science Journal Classification (ASJC) codes
- Cancer Research