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The role of hormonal factors in the etiology of lymphoid neoplasms remains unclear. Previous studies have yielded conflicting results, have lacked sufficient statistical power to assess many lymphoma subtypes, or have lacked detailed information on relevant exposures. Within the European Prospective Investigation Into Cancer and Nutrition cohort, we analyzed comprehensive data on reproductive factors and exogenous hormone use collected at baseline (1992-2000) among 343,458 women, including data on 1,427 incident cases of B-cell non-Hodgkin lymphoma (NHL) and its major subtypes identified after a mean follow-up period of 14 years (through 2015). We estimated hazard ratios and 95% confidence intervals using multivariable proportional hazards modeling. Overall, we observed no statistically significant associations between parity, age at first birth, breastfeeding, oral contraceptive use, or ever use of postmenopausal hormone therapy and risk of B-cell NHL or its subtypes. Women who had undergone surgical menopause had a 51% higher risk of B-cell NHL (based on 67 cases) than women with natural menopause (hazard ratio = 1.51, 95% confidence interval: 1.17, 1.94). Given that this result may have been due to chance, our results provide little support for the hypothesis that sex hormones play a role in lymphomagenesis.

The worldwide incidence of gastric adenocarcinoma (GC) is lower in women than in men. Furthermore, cancer patients treated with estrogens have been reported to have a lower subsequent risk of GC. The authors conducted a prospective analysis of menstrual and reproductive factors, exogenous hormone use, and GC in 335,216 women from the European Prospective Investigation Into Cancer and Nutrition, a cohort study of individuals aged 35-70 years from 10 European countries. After a mean follow-up of 8.7 years (through 2004), 181 women for whom complete exposure data were available developed GC. Adjusted hazard ratios and 95% confidence intervals were estimated using Cox proportional hazards models. All statistical tests were 2-sided. Women who had ovariectomy had a 79% increased risk of GC (based on 25 cases) compared with women who did not (hazard ratio = 1.79, 95% confidence interval: 1.15, 2.78). Total cumulative years of menstrual cycling was inversely associated with GC risk (fifth vs. first quintile: hazard ratio = 0.55, 95% confidence interval: 0.31, 0.98; P(trend) = 0.06). No other reproductive factors analyzed were associated with risk of GC. The results of this analysis provide some support for the hypothesis that endogenous ovarian sex hormones lower GC incidence in women.