科研之友
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摘要
Background: Previous epidemiologic studies have reported inconsistent results between parity and pancreatic cancer (PC) risk. To our knowledge, a comprehensive and quantitative assessment of this association has not been conducted. Methods: Relevant published studies of parity and PC were identified using MEDLINE (PubMed) and Web of Science databases until November 2013. Two authors (H-BG and LW) independently assessed eligibility and extracted data. Eleven prospective and 11 case-control studies reported relative risk (RR) estimates and 95% confidence intervals (CIs) of PC associated with parity. Fixed-and random-effects models were used to estimate the summary RR depending on the heterogeneity of effects. Results: The summary RR for PC comparing the highest versus lowest parity was 0.86 (95% CI: 0.73-1.02; Q = 50.49, P<0.001, I-2 = 58.4%). Significant inverse associations were also observed in the studies that adjusted for cigarette smoking (RR = 0.81; 95% CI: 0.68-0.98), Type 2 diabetes mellitus (RR = 0.83; 95% CI: 0.75-0.93), and those that included all confounders or important risk factors (RR = 0.85; 95% CI: 0.76-0.96). Additionally, in the dose-response analysis, the summary RR for per one live birth was 0.97 (95% CI: 0.94-1.01; Q = 62.83, P<0.001, I-2 = 69.8%), which also indicated a borderline statistically significant inverse effect of parity on PC risk. No evidence of publication bias and significant heterogeneity between subgroups were detected by meta-regression analyses. Conclusion: In summary, these findings suggest that higher parity is associated with a decreased risk of PC. Future large consortia or pooled studies are warranted to fully adjust for potential confounders to confirm this association.
