title: Parity and endometrial cancer risk: a meta-analysis of epidemiological studies.
abstract: The association between parity and endometrial cancer risk is inconsistent from observational studies. We aimed to quantitatively assess the relationship by summarizing all relevant epidemiological studies. PubMed (MEDLINE), Embase and Scopus were searched up to February 2015 for eligible case-control studies and prospective studies. Random-effects model was used to pool risk estimations. Ten prospective studies, 35 case-control studies and 1 pooled analysis of 10 cohort and 14 case-control studies including 69681 patients were identified. Pooled analysis revealed that there was a significant inverse association between parity and risk of endometrial cancer (relative risk (RR) for parous versus nulliparous: 0.69, 95% confidence interval (CI) 0.65-0.74; I(2) = 76.9%). By evaluating the number of parity, we identified that parity number of 1, 2 or 3 versus nulliparous demonstrated significant negative association (RR = 0.73, 95% CI 0.64-0.84, I(2) = 88.3%; RR = 0.62, 95% CI 0.53-0.74, I(2) = 92.1%; and RR = 0.68, 95% CI 0.65-0.70, I(2) = 20.0% respectively). The dose-response analysis suggested a nonlinear relationship between the number of parity and endometrial cancer risk. The RR decreased when the number of parity increased. This meta-analysis suggests that parity may be associated with a decreased risk of endometrial cancer. Further studies are warranted to replicate our findings.
authors.affiliation: Department of Clinical Epidemiology, Shengjing Hospital of China Medical University, Shenyang 110004, Liaoning, China.
authors.forename: Qi-Jun
authors.initials: QJ
authors.lastname: Wu
authors.affiliation: Department of Hematology, the Affiliated Hospital of Xuzhou Medical College, Xuzhou, Jiangsu, 221000, China.
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Li
authors.affiliation: Oncology Institute, the Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, Jiangsu, 213003, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Tu
authors.affiliation: Program of Quantitative Methods in Education, University of Minnesota, Minneapolis, Minnesota, 55455, USA.|Division of Epidemiology, Department of Medicine, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, TN 37203, USA.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Oncology Institute, the Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, Jiangsu, 213003, China.
authors.forename: Ke-Qing
authors.initials: KQ
authors.lastname: Qian
authors.affiliation: Oncology Institute, the Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, Jiangsu, 213003, China.
authors.forename: Tong-Bao
authors.initials: TB
authors.lastname: Feng
authors.affiliation: Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, 70112, USA.
authors.forename: Changwei
authors.initials: C
authors.lastname: Li
authors.affiliation: Center for Clinical and Translational Science, Mayo Clinic, Rochester, Minnesota, 55905, USA.|Division of Epidemiology, Department of Medicine, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, TN 37203, USA.
authors.forename: Lang
authors.initials: L
authors.lastname: Wu
authors.affiliation: Department of Obstetrics and Gynecology, Shengjing Hospital of China Medical University, Shenyang 110004, Liaoning, China.
authors.forename: Xiao-Xin
authors.initials: XX
authors.lastname: Ma
mesh_terms: D016889:Endometrial Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D005260:Female; D006801:Humans; D016017:Odds Ratio; D010298:Parity; D011247:Pregnancy; D012306:Risk