Coffee consumption and risk of renal cell carcinoma in the NIH-AARP Diet and Health Study.

BACKGROUND

Coffee consumption has been associated with a reduced risk of some cancers, but the evidence for renal cell carcinoma (RCC) is inconclusive. We investigated the relationship between coffee and RCC within a large cohort.

METHODS

Coffee intake was assessed at baseline in the National Institutes of Health-American Association of Retired Persons Diet and Health Study. Among 420 118 participants eligible for analysis, 2674 incident cases were identified. We fitted Cox-regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for coffee consumption vs non-drinkers.

RESULTS

We observed HRs of 0.94 (95% CI 0.81, 1.09), 0.94 (0.81, 1.09), 0.80 (0.70, 0.92) and 0.77 (0.66, 0.90) for usual coffee intake of <1, 1, 2-3 and ≥4 cups/day, respectively (Ptrend = 0.00003). This relationship was observed among never-smokers (≥4 cups/day: HR 0.62, 95% CI 0.46, 0.83; Ptrend = 0.000003) but not ever-smokers (HR 0.85, 95% CI 0.70, 1.05; Ptrend = 0.35; Pinteraction = 0.0009) and remained in analyses restricted to cases diagnosed >10 years after baseline (HR 0.65, 95% CI 0.51, 0.82; Ptrend = 0.0005). Associations were similar between subgroups who drank predominately caffeinated or decaffeinated coffee (Pinteraction = 0.74).

CONCLUSION

In this investigation of coffee and RCC, to our knowledge the largest to date, we observed a 20% reduced risk for intake of ≥2 cups/day vs not drinking. Our findings add RCC to the growing list of cancers for which coffee consumption may be protective.