title: Breastfeeding and ovarian cancer risk: a systematic review and meta-analysis of 40 epidemiological studies.
abstract: The present systematic review and meta-analysis was conducted to assess any association between breastfeeding and the risk of ovarian cancer. A systematic search of published studies was performed in PUBMED and EMBASE and by reviewing reference lists from retrieved articles through March 2013. Data extraction was conducted independently by two authors. Pooled relative risk ratios were calculated using random-effect models. Totals of 5 cohort studies and 35 case-control studies including 17,139 women with ovarian cancer showed a 30% reduced risk of ovarian cancer when comparing the women who had breastfed with those who had never breastfed (pooled RR = 0.70, 95% CI: 0.64-0.76; p = 0.00), with significant heterogeneity in the studies (p = 0.00; I2 = 76.29%). A significant decreasd in risk of epithelial ovarian cancer was also observed (pooled RR = 0.68, 95% CI: 0.61-0.76). When the participants were restricted to only parous women, there was a slightly attenuated but still significant risk reduction of ovarian cancer (pooled RR = 0.76, 95% CI: 0.69-0.83). For total breastfeeding duration, the pooled RRs in the < 6 months, 6-12 months and > 12 months of breastfeeding subgroups were 0.85 (95% CI: 0.77-0.93), 0.73 (95% CI: 0.65-0.82) and 0.64 (95%CI: 0.56-0.73), respectively. Meta-regression of total breastfeeding duration indicated an increasing linear trend of risk reduction of ovarian cancer with the increasing total breastfeeding duration (p = 0.00). Breastfeeding was inversely associated with the risk of ovarian cancer, especially long-term breastfeeding duration that demonstrated a stronger protective effect.
authors.affiliation: Department of Epidemiology, School of Public Health, Harbin Medical University, Harbin, China E-mail : liuyupeng@ems.hrbmu.edu.cn, zhao_yashuang@263.net.
authors.forename: Da-Peng
authors.initials: DP
authors.lastname: Li
authors.forename: Chen
authors.initials: C
authors.lastname: Du
authors.forename: Zuo-Ming
authors.initials: ZM
authors.lastname: Zhang
authors.forename: Guang-Xiao
authors.initials: GX
authors.lastname: Li
authors.forename: Zhi-Fu
authors.initials: ZF
authors.lastname: Yu
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Li
authors.forename: Cheng
authors.initials: C
authors.lastname: Cheng
authors.forename: Yu-Peng
authors.initials: YP
authors.lastname: Liu
authors.forename: Ya-Shuang
authors.initials: YS
authors.lastname: Zhao
mesh_terms: D001942:Breast Feeding; D000077216:Carcinoma, Ovarian Epithelial; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D009375:Neoplasms, Glandular and Epithelial / Q000453:epidemiology* / Q000517:prevention & control; D010051:Ovarian Neoplasms / Q000453:epidemiology* / Q000517:prevention & control; D011379:Prognosis; D012307:Risk Factors