The Effect of Breastfeeding Duration and Parity on the Risk of Epithelial Ovarian Cancer: A Systematic Review and Meta-analysis

• Main Authors: Ho Kyung Sung, Seung Hyun Ma, Ji-Yeob Choi, Yunji Hwang, Choonghyun Ahn, Byoung-Gie Kim, Yong-Man Kim, Jae Weon Kim, Sokbom Kang, Jaehoon Kim, Tae Jin Kim, Keun-Young Yoo, Daehee Kang, Suekyung Park
• Format: Article
• Language: English
• Published: Korean Society for Preventive Medicine 2016-11-01
• Series: Journal of Preventive Medicine and Public Health
• Subjects: Ovarian neoplasms; Parity; Breast feeding; Reproduction; Risk factors; Meta-analysis
• Online Access: http://www.jpmph.org/upload/pdf/jpmph-49-6-349.pdf
• ISSN: 1975-8375; 2233-4521

Objectives We conducted a systematic review and meta-analysis to summarize current evidence regarding the association of parity and duration of breastfeeding with the risk of epithelial ovarian cancer (EOC). Methods A systematic search of relevant studies published by December 31, 2015 was performed in PubMed and EMBASE. A random-effect model was used to obtain the summary relative risks (RRs) and 95% confidence intervals (CIs). Results Thirty-two studies had parity categories of 1, 2, and ≥3. The summary RRs for EOC were 0.72 (95% CI, 0.65 to 0.79), 0.57 (95% CI, 0.49 to 0.65), and 0.46 (95% CI, 0.41 to 0.52), respectively. Small to moderate heterogeneity was observed for one birth (p<0.01; Q=59.46; I2=47.9%). Fifteen studies had breastfeeding categories of <6 months, 6-12 months, and >13 months. The summary RRs were 0.79 (95% CI, 0.72 to 0.87), 0.72 (95% CI, 0.64 to 0.81), and 0.67 (95% CI, 0.56 to 0.79), respectively. Only small heterogeneity was observed for <6 months of breastfeeding (p=0.17; Q=18.79, I2=25.5%). Compared to nulliparous women with no history of breastfeeding, the joint effects of two births and <6 months of breastfeeding resulted in a 0.5-fold reduced risk for EOC. Conclusions The first birth and breastfeeding for <6 months were associated with significant reductions in EOC risk.