ArticleCancer medicine2021
Impact of reproductive factors on breast cancer incidence: Pooled analysis of nine cohort studies in Japan.
Article in Cancer medicine, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 8 papers, 1 of them a synthesis that pooled it.
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Who cites it
8 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Systematic Review and Meta-Analysis of Lifestyle and Reproductive Factors Associated with Risk of Breast Cancer in Asian Women.Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology · 2024Pooled it
- Predictive performance of breast cancer polygenic risk scores from diverse ancestries: a prospective study in Japanese women.Breast cancer research : BCR · 2026Article
- Ethnic Heterogeneity in Reproductive Risk Factors for Breast Cancer, With a Focus on Asian Populations: A Meta-analysis.Journal of cancer prevention · 2026Article
- Impact of breast size and composition on the accuracy of mammography and ultrasonography in breast cancer screening.Breast cancer (Tokyo, Japan) · 2025Article
- Breast cancer risk assessment based on a predictive model: evaluation of risk factors among Japanese women.BMC cancer · 2025Article
- Potential Risk and Protective Factors in High- and Low-incidence Breast Cancer Populations in Northeast India: A Cross-sectional Study.Asian Pacific journal of cancer prevention : APJCP · 2025Article
- The Japanese Breast Cancer Society clinical practice guidelines for epidemiology and prevention of breast cancer, 2022 edition.Breast cancer (Tokyo, Japan) · 2024Article
- The Causal Effect of Reproductive Factors on Breast Cancer: A Two-Sample Mendelian Randomization Study.Journal of clinical medicine · 2023Article
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23 authors.
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Abstract
Prior studies reported the association of reproductive factors with breast cancer (BC), but the evidence is inconsistent. We conducted a pooled analysis of nine cohort studies in Japan to evaluate the impact of six reproductive factors (age at menarche/age at first birth/number of births/age at menopause/use of female hormones/breastfeeding) on BC incidence. We conducted analyses according to menopausal status at the baseline or at the diagnosis. Hazard ratio (HR) and 95% confidence interval (CI) were estimated by applying Cox proportional-hazards model in each study. These hazard ratios were integrated using a random-effects model. Among 187,999 women (premenopausal: 61,113, postmenopausal: 126,886), we observed 873 premenopausal and 1,456 postmenopausal cases. Among premenopausal women, use of female hormones significantly increased BC incidence (HR: 1.53 [1.04-2.25]). Although P value for trend was not significant for age at first birth and number of births (P for trend: 0.15 and 0.30, respectively), women giving first birth at ages ≥36 experienced significantly higher BC incidence than at ages 21-25 years, and women who had ≥2 births experienced significantly lower BC incidence than nulliparous women. Among postmenopausal women, more births significantly decreased BC incidence (P for trend: 0.03). Although P value for trend was not significant for age at first birth and age at menopause (P for trend: 0.30 and 0.37, respectively), women giving first birth at ages 26-35 years experienced significantly higher BC incidence than at ages 21-25 years, and women with age at menopause: ≥50 years experienced significantly higher BC incidence than age at menopause: ≤44 years. BC incidence was similar according to age at menarche or breastfeeding history among both premenopausal and postmenopausal women. In conclusion, among Japanese women, use of female hormones increased BC incidence in premenopausal women, and more births decreased BC incidence in postmenopausal women.
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