Consumption of fruits and vegetables and risk of renal cell carcinoma: a meta-analysis of observational studies
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Shaojin Zhang1, Zhankui Jia1, Zechen Yan1, Jinjian Yang1
1Department of Urology Surgery, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan Province, China
Jinjian Yang, email: email@example.com
Keywords: fruits and vegetables, renal cell carcinoma, meta-analysis, relative risk
Received: November 17, 2016 Accepted: February 20, 2017 Published: March 02, 2017
Background: There have been inconsistent results about the association between consumption of fruits and vegetables and renal cell carcinoma (RCC) risk. We conducted a meta-analysis of the published observational studies to explore this association.
Results: Nineteen observational studies (4 cohort, 1 pooled and 14 case-control studies), involving 10,215 subjects with RCC were part of this meta-analysis. The SRR for the highest vs. the lowest intake of vegetables was 0.73 (95% CI: 0.63–0.85; Pheterogeneity = 0.004, I2 = 53.5%), whereas for fruits it was 0.86 (95% CI: 0.75–0.98; Pheterogeneity = 0.012, I2 = 47.4%). Linear dose-response analysis also showed similar results, e.g., for per 1 serving/day increment of vegetables, the SRR was 0.90 (95% CI: 0.84–0.96) and for fruits it was 0.97 (95% CI: 0.93–1.01). Nonlinear association was only observed for vegetables (Pnonlinearity = 0.001), but not for fruits (Pnonlinearity = 0.221).
Materials and Methods: Eligible studies up to August 31, 2016 were identified and retrieved by searching MEDLINE and EMBASE databases along with manual review of the reference list from the retrieved studies. Quality of included studies was evaluated using Newcastle-Ottawa Quality Assessment Scale (NOS). Random-effects model was used to calculate summary relative risk (SRR) and corresponding 95% confidence interval (CI).
Conclusions: This meta-analysis indicated a protective effect of consumption of vegetables and fruits on RCC risk. Further studies are warranted with prospective designs that use validated questionnaires and control for important confounders.
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