Abstract 5263: Association between urinary tea catechins and risk of gastric cancer: A nested case-control study within the Shanghai Cohort Study
Authors: Samavat Hamed , Wang Renwei , Yang Chung S. , Gao Yu-Tang , Yuan Jian-Min 
Published: August 2018

Abstract
Background: Findings from in vitro and animal studies suggest a protective role for green tea consumption against gastric cancer risk; however, data from observational studies are inconsistent and mostly based on self-reported dietary intake. To date, very few studies have investigated the association between tea catechins and gastric cancer risk using a biomarker-based approach.
Methods: We analyzed data from 300 incident gastric cancer cases and 905 controls nested within a prospective population-based cohort of 18,244 middle-aged and older men in Shanghai, China. Control subjects were matched to case patients by age (± 2 years), date of sample collection (± 1 month), and neighborhood of residence at recruitment. Tea catechins including epicatechin (EC); epigallocatechin (EGC); methylated-EGC (Me-EGC); 5-(3′,4′,5′-trihydroxy-phenyl)-γ-valerolactone (M4); and 5-(3′,4′-dihydroxy-phenyl)-γ-valerolactone (M6) were measured in pre-diagnostic urine specimens collected between 1986 and 1989 using a validated high-performance liquid chromatography method. Odds ratios (ORs) and 95% confidence intervals (CIs) of gastric cancer by quintiles of tea catechins levels were estimated by unconditional logistic regression models, adjusting for potential confounders.
Results: Compared to control subjects, cancer patients were less educated with higher prevalences of smoking, alcohol drinking and seropositivity of Helicobactor pylori. Although not statistically significant, cases showed higher levels of urinary tea catechins relative to controls. Among control subjects, levels of urinary catechins were significantly positively associated with consumption of tea. After adjusting for matching factors and selected known risk factors, men with the highest quintiles of urinary EC, Me-EGC, and M6 had significantly higher risk of gastric cancer compared to those in the lowest quintiles (OR = 1.59, 95% CI = 0.98 to 2.58, P trend = 0.04 for EC; OR = 1.47, 95% CI = 0.86 to 2.49, P trend = 0.02 for Me-EGC; OR = 1.64, 95% CI = 1.06 to 2.55, P trend = 0.01 for M6). Corresponding risks were slightly stronger among cases with Helicobactor pylori seropositivity status. When the analysis was limited to ever smokers or drinkers, the OR (95% CI) comparing top versus bottom quintiles of Me-EGC were 2.05 (1.06 to 3.97; P trend = 0.01) and 2.17 (0.98 to 4.79; P trend = 0.04), respectively; however, we did not observe significant interaction between Me-EGC and smoking or alcohol drinking status on risk of gastric cancer.
Conclusion: In contrast to some previous findings, we found that tea catechins are associated with increased risk of gastric cancer. The impact of tea catechins on the risk of gastric cancer may differ by smoking or alcohol drinking status.
Funding source: NIH/NCI (R01 CA144034 and UM1 CA182876).
Citation Format: Hamed Samavat, Renwei Wang, Chung S. Yang, Yu-Tang Gao, Jian-Min Yuan. Association between urinary tea catechins and risk of gastric cancer: A nested case-control study within the Shanghai Cohort Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5263.