Menstrual and reproductive factors and pancreatic cancer in the SEARCH program of the IARC.

We conducted a population-based case-control study on the relation of menstrual and reproductive factors and hormone use with pancreatic cancer risk among female participants of the SEARCH program study. We evaluated 367 cases of ductal adenocarcinoma and 821 controls for associations between pancreatic cancer and age at menarche, age at menopause, number of pregnancies, exogenous hormone use, and history of gynaecologic surgery. Among directly interviewed and proxy participants, we found a statistically significant association for having age of menarche at 11 years or younger compared with menarche at ages 12-13 years (OR = 1.8, 95% CI = 1.1-3.1). This result was consistent, but not statistically significant, among three of the four studies analyzed, and when the data were analyzed separately by response status (direct vs. proxy interviews). No other menstrual or reproductive factors were associated with pancreatic cancer risk in this study. In conclusion, earlier age at menarche may be weakly associated with pancreatic cancer, but it seems unlikely that menstrual and reproductive factors play more than only a minor role in pancreatic cancer. Additional analyses in large prospective study populations and in pooled studies may help to clarify remaining inconsistencies.