Abstract 2276: Effect modification by isoflavones on the association between salt intake and gastric cancer risk: A case-cohort study within the Korean multi-center cancer cohort

Abstract

Abstract Backgrounds: Attenuation by genistein, an isoflavone abundant in soybean, of gastric carcinogenesis induced by sodium chloride was reported in an animal study. Up to date, role of isoflavone as an effect modifier on the association between salt intake and gastric cancer risk is not clearly established. Methods: We randomly selected 640 subcohort subjects without cancer history at enrollment from the Korean multi-center cancer cohort participants. Ninety-nine gastric cancer cases were identified from the inside (N=8) and the outside (N=91) of the subcohort after the 12.2 years of median follow-up time. To estimate individual’s salt intake, we measured 24-hour urinary sodium excretion from spot urine using the Tanaka’s equation. Three isoflavone plasma concentrations (Genistein, daidzein, and equol) of 167 subjects among case-cohort subjects had been measured using time-resolved fluoroimmunoassay. Cubic spline curve for gastric cancer risk according to urinary sodium level was used to define optimal cut-off points of urinary sodium excretion concentration. Weighted Cox proportional hazard regression was used to calculate hazard ratios (HRs) and their 95% confidence intervals (CIs). Stratified analysis by isoflavone level was conducted to assess effect modification by isoflavone on the association between salt intake and gastric cancer. Results: Gastric cancer risk in the high salt intake group (urinary sodium excretion ≥6,000mg/day) was significantly increased (HR, 1.69; 95% CI, 0.99-2.90) compared to the reference group (urinary sodium excretion 4500-5,999mg/day). Magnitudes of gastric cancer risk by high salt intake were more strengthened in the group with low plasma isoflavone concentrations (One or no genistein, diadzein or equol levels over the median concentrations) (HR, 6.92; 95% CI, 1.80-26.56). Contrary to the low isoflavone group, no significant differences in gastric cancer risk according to salt intake levels were found in the group with high isoflavone concentration. Conclusions: High salt intake is associated with gastric cancer risk, but this association can be attenuated by high concentration of isoflavones. We suggest that sufficient intake of soybean products, the rich sources of isoflavone, may give protection against gastric cancer in the population with high salt intake. Citation Format: Jieun Jang, Yunji Hwang, Choonghyun Ahn, Kwang-Pil Ko, Aesun Shin, Keun-Young Yoo, Sue K. Park. Effect modification by isoflavones on the association between salt intake and gastric cancer risk: A case-cohort study within the Korean multi-center cancer cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2276. doi:10.1158/1538-7445.AM2017-2276