Pancreatic cancer incidence in relation to female reproductive factors: Iowa women's health study

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, 0.40-0.94) 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.