Parity, other reproductive factors, and risk of pancreatic cancer mortality in a large cohort of U.S. women (United States).

Several studies have found an inverse relationship between parity and risk of pancreatic cancer. However, most of the studies of pancreatic cancer in relation to parity and other reproductive factors have been small and the results inconsistent. Most recently, a well-conducted, prospective cohort study found a linear inverse association between parity and pancreatic cancer. To clarify the relationship between parity and other reproductive factors and risk of pancreatic mortality, we examined these associations among 387,981 postmenopausal U.S. women in the Cancer Prevention Study (CPS)-II cohort. CPS-II participants completed a self-administered questionnaire in 1982 and were followed for mortality through 2000. During follow-up, 1959 pancreatic cancer deaths occurred. Using Cox proportional hazards modeling, we calculated rate ratios (RR) adjusted for age, race, education, personal history of diabetes, body mass index, height, exercise, family history of pancreatic cancer, and cigarette smoking status, frequency, and duration. Overall, we did not observe a significant association between parity and pancreatic cancer mortality (trend p = 0.07). However, women who had five or more births had lower death rates from pancreatic cancer than nulliparous women (RR = 0.80, 95% CI = 0.66-0.96). We observed no association between any other reproductive factors examined (age at first birth, menarche, or menopause; type of menopause; diethylstilbestrol (DES) use; or duration of oral contraceptive or estrogen replacement therapy use) and pancreatic cancer mortality. In summary, our results support the observation that high parity is associated with lower risk of pancreatic cancer but do not show a linear trend with increasing parity. Furthermore, we find no evidence that other reproductive factors are associated with pancreatic cancer mortality.