Lung Cancer
Volume 76, Issue 2 , Pages 150-158, May 2012

Parity and risk of lung cancer in women: Systematic review and meta-analysis of epidemiological studies

  • Issa J. Dahabreh

      Affiliations

    • Center for Clinical Evidence Synthesis, Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, 800 Washington Street #63, Boston, MA, United States
    • Corresponding Author InformationCorresponding author. Tel.: +1 617 636 1459; fax: +1 617 636 8628.
    • ,
  • Thomas A. Trikalinos

      Affiliations

    • Center for Clinical Evidence Synthesis, Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, 800 Washington Street #63, Boston, MA, United States
    • ,
  • Jessica K. Paulus

      Affiliations

    • Tufts Clinical and Translational Science Institute, Tufts University, Medford, MA, United States
    • Department of Epidemiology, Harvard School of Public Health, Boston, MA, United States

Received 13 June 2011; received in revised form 7 September 2011; accepted 19 October 2011. published online 12 December 2011.

Abstract 

Multiple studies have assessed parity as a risk factor for lung cancer but results have been inconclusive. We searched MEDLINE (through August 2010) and the Institute of Scientific Information Web of Knowledge database (through April 2011) to identify studies investigating the association of parity with lung cancer and allowing the calculation of dose–response trends using a linear model. Between-study heterogeneity was assessed using Cochran's Q statistic and the I2 index. Summary per-child relative risks (RRs) with their 95% confidence interval (CI) were estimated using random effects meta-analysis. Sixteen eligible studies (8077 lung cancer patients; 350,295 unaffected individuals) provided data for meta-analysis. There was significant between-study heterogeneity (p<0.001; I2=73%). The summary per livebirth RR was 0.98 (95% CI, 0.95–1.02), indicating no effect of parity on lung cancer risk. Results were consistent in case–control (n=11), RR=0.99 (95% CI, 0.94–1.04), and cohort studies (n=5), RR=0.97 (95% CI, 0.92–1.03). Studies not including small-cell lung cancer patients found a borderline protective effect of parity, RR=0.94 (95% CI, 0.88–1.00). In contrast, no effect was observed in studies including small-cell lung cancer patients, RR=1.00 (95% CI, 0.98–1.03); p for difference=0.05. Overall, there was little evidence of a dose–response relationship between increasing number of livebirths and lung cancer; however, studies have produced heterogeneous results. Future studies should include analyses in well-defined histological disease subgroups.

Abbreviations: CI, confidence interval, IQR, inter-quartile range, ISI, Institute of Scientific Information, MOOSE, Meta-analysis of Observational Studies in Epidemiology, NSCLC, non-small cell lung cancer, RR, relative risk, STROBE, STrengthening the Reporting of OBservational studies in Epidemiology

Keywords: Parity, Lung cancer, Meta-analysis, Systematic review, Women's health

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PII: S0169-5002(11)00529-0

doi:10.1016/j.lungcan.2011.10.014

Lung Cancer
Volume 76, Issue 2 , Pages 150-158, May 2012

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