Reproductive and Hormonal Factors and Lung Cancer Risk in the NIH-AARP Diet and Health Study Cohort

Lung cancer exhibits unique patterns among women including high adenocarcinoma rates among nonsmokers. Inconsistent findings about hormonal factors on risk may reflect incomplete control for confounding, misclassification of exposures, or insufficient attention to variation by histology. Among 185,017 women, ages 50 to 71 years, recruited during 1995 and 1996 for the NIH-AARP (American Association of Retired Persons) Diet and Health Study, we identified 3,512 incident lung cancers (including 276 in never smokers) in follow-up through December 2006. Multivariable Cox proportional hazards models estimated relative risks (RR) and 95% CIs for self-reported hormonally related risk factors. After adjustment for smoking and other confounders, subjects with late menarche were at reduced risk, with the association specific for adenocarcinomas (RR = 0.72 for menarche 15+ vs.