Serum Levels of Androgens, Estrogens, and Sex Hormone Binding Globulin and Risk of Primary Gastric Cancer in Chinese Men: A Nested Case-Control Study.

Gastric cancer shows a strong male predominance, and sex steroid hormones have been hypothesized to explain this sex disparity. Previous studies examining the associations between sex hormones and sex hormone binding globulin (SHBG) and risk of gastric cancer come primarily from western populations and additional studies in diverse populations will help us better understand the association. We performed a nested case-control study in Linxian Nutrition Intervention Trials cohorts to evaluate the associations among Chinese men, where we had sufficient cases to perform a well-powered study. Using radioimmunoassays and immunoassays, we quantitated androgens, estrogens, and SHBG in baseline serum from 328 men that developed non-cardia gastric cancer and matched controls. We used multivariable unconditional logistic regression to calculate odds ratios (ORs) and 95% confidence intervals (CIs) and explored interactions with body mass index (BMI), age, alcohol drinking, smoking, and follow-up time. Subjects with SHBG in the highest quartile, as compared to those in the lowest quartile, had a significantly increased risk of gastric cancer (OR=1.87, 95% CI=1.01, 3.44). We found some evidence for associations of sex steroid hormones in men with lower BMI. Our study found a novel association suggesting that higher serum concentrations of SHBG may be associated with risk of gastric cancer in men. We found no overall associations with sex hormones themselves, but future studies should expand the scope of these studies to include women and further explore whether BMI modifies a potential association.