Epidemiological data on the role of reproductive factors and menstrual history in the development of pancreatic cancer

Objective Motivated by inconsistent literature, we evaluated the association between incident pancreatic cancer and reproductive characteristics. Design The Iowa Women’s Health Study is a large prospective population-based cohort followed from 1986 to 2003. Reproductive information was self-reported. Participants The study population comprised 37,459 women aged 55-69 years at baseline. Over 18 years, 228 incident pancreatic cancers were identified. Results In a multivariate-adjusted model there were no associations between incident pancreatic cancer and age at first birth, number of births, age at menarche, or use of hormones. There was a statistically significant inverse association between age at menopause and pancreatic cancer incidence. Compared to menopause less than 45 years, the hazard ratio of pancreatic cancer was 0.61 (95% CI, 0.400.94) for menopause at 45-49 years, 0.75 (95% CI, 0.51-1.09) for 50-54 years, and 0.35 (95% CI, 0.18-0.68) for menopause at 55 years or more (P trend=0.005). This association held after restricting the cohort to never smokers. The associations between pancreatic cancer and ages at natural and surgical menopause followed similar patterns. In a parallel fashion, risk of pancreatic cancer was decreased for women with intact ovaries compared to those who had oophorectomy: hazard ratio was 0.70 (95% CI, 0.50-0.99). Conclusions Our results indicate that older age at menopause is associated with reduced pancreatic cancer risk, but further research is warranted.