Abstract 4650: Coffee consumption and risk of renal cell carcinoma in the NIH-AARP Diet and Health Study
Authors: Rhee Jongeun , Loftfield Erikka , Freedman Neal D. , Liao Linda M. , Sinha Rashmi , Purdue Mark P. 
Published: September 2020

Abstract
Background: Coffee consumption has been associated with lower all-cause mortality; however, its relationship to cancer risk is unclear. Evidence of inverse associations with cancers of the endometrium and liver were noted in a 2016 expert panel review convened by the International Agency for Research on Cancer, while findings for other malignancies were inconclusive. In the case of coffee and renal cell carcinoma (RCC), past studies have been limited by inadequate statistical power to detect modest effect sizes. To address this weakness in the existing literature, we investigated the relationship between coffee consumption and RCC risk in a large prospective cohort.
Methods: Coffee intake was assessed at baseline with a food frequency questionnaire in the National Institutes of Health-AARP Diet and Health Study. Among 420,139 participants who were cancer-free at baseline, 2,674 incident cases of RCC were identified with a median of 16 years of follow-up. We fit multivariable-adjusted Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for coffee intake, with non-coffee drinkers as the reference group. We also conducted stratified analysis by sex, diabetes, and smoking status and subgroup analyses by consumption of predominately caffeinated vs. decaffeinated coffee.
Results: We observed HRs for RCC of 0.95 (95% CI 0.82, 1.10), 0.95 (0.81, 1.10), 0.80 (0.70, 0.92) and 0.76 (0.65, 0.89) for usual coffee intake of &lt;1, 1, 2-3 and 4+ cups per day respectively (Ptrend &lt;0.00001). In sex-specific analyses the inverse relationship was observed among men (4+ cups per day: HR 0.70, 95% CI 0.58, 0.83; Ptrend &lt;0.0001) but not women (HR 0.98, 95% CI 0.71, 1.35; Ptrend=0.12; Pinteraction=0.004). However, when restricting to non-smokers, we observed associations with coffee in both sexes (4+ cups per day: men: HR 0.68, 95% CI 0.48, 0.96, Ptrend = 0.002; women: HR 0.47, 95% CI 0.24, 0.91; Ptrend=0.0003). In other stratified analyses, the reduced risk for coffee remained in analyses restricted to those without a self-reported history of diabetes (HR 0.78, 95% CI 0.66, 0.92; Ptrend &lt;0.0001) and was slightly stronger for usual caffeinated coffee drinkers (HR 0.66, 95% CI 0.54, 0.80; Ptrend &lt;0.00001) than usual decaffeinated coffee drinkers (HR 0.76, 95% CI 0.57, 1.00; Ptrend=0.12), although a test of interaction was not significant (P=0.13). Our findings did not meaningfully change when we repeated our analyses excluding the first five years of follow-up.
Conclusions: In this analysis of coffee consumption and RCC risk, to our knowledge the largest of its kind, we observed an approximately 20% reduced cancer risk for coffee consumption of 2 or more cups per day. Our findings provide the strongest epidemiologic evidence to date supporting an inverse association between coffee and RCC.
Citation Format: Jongeun Rhee, Erikka Loftfield, Neal D. Freedman, Linda M. Liao, Rashmi Sinha, Mark P. Purdue. Coffee consumption and risk of renal cell carcinoma in the NIH-AARP Diet and Health Study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4650.