Intake of red and processed meat and risk of renal cell carcinoma: a meta-analysis of observational studies

BACKGROUND Findings on the association between intake of red and processed meat with renal cell carcinoma (RCC) risk are mixed. We conducted a meta-analysis to investigate this association. MATERIALS AND METHODS Eligible studies up to August 31, 2016, were identified and retrieved by searching the MEDLINE and Embase databases along with manual review of the reference lists from the retrieved studies. The quality of the included studies was evaluated using the Newcastle-Ottawa Quality Assessment Scale. The summary relative risk (SRR) and corresponding 95% confidence interval (CI) were calculated using a random-effects model. RESULTS Twenty-three publications were included in this meta-analysis: four cohort studies, one pooled study, and 18 case-control studies. The SRR (95% CI) for the highest vs. lowest intake of red meat was 1.36 (1.16-1.58, Pheterogeneity < 0.001); that for processed meat was 1.13 (95% CI, 1.03-1.24, Pheterogeneity = 0.014). Linear dose-response analysis yielded similar results, i.e., the SRR for per 100 g/day increment of red meat and per 50 g/day increment of processed meat was 1.21 (95% CI, 1.08-1.36) and 1.16 (95% CI, 0.99-1.36), respectively. A non-linear association was observed only for red meat (Pnonlinearity = 0.002), and not for processed meat (Pnonlinearity = 0.231). Statistically significant positive associations were observed for intake of beef, salami/ham/bacon/sausage, and hamburger. CONCLUSIONS This meta-analysis indicates a significant positive association between red and processed meat intake and RCC risk.