Dietary intake of nutrients involved in one-carbon metabolism and risk of urothelial cell carcinoma: A prospective cohort study

Abstract

Nutrients involved in one-carbon metabolism may play a role in carcinogenesis through DNA replication, repair and methylation mechanisms. Most studies on urothelial cell carcinoma (UCC) have focused on folate. We sought to examine the association between B-group vitamins and methionine intake and UCC risk, overall and by subtype, and to test whether these associations are different for population subgroups whose nutritional status may be compromised. We followed participants in the Melbourne Collaborative Cohort Study (N=41,513) for over 20 years, and observed 500 UCC cases (89% originating in the bladder; superficial: 279, invasive: 221). Energy-adjusted dietary intakes of B vitamins (B1, B2, B3, B5, B6, B8, B9, and B12) and methionine were estimated from a 121-item food frequency questionnaire administered at baseline (1990-1994), using the residuals method. We used Cox regression models to compute hazard ratios (HR) of UCC risk per standard deviation of log-transformed nutrient intakes and 95% confidence intervals (CI), adjusted for potential confounders. We investigated associations by tumour subtype, and tested interactions with sex, country of birth, smoking, and alcohol drinking. The risk of UCC appeared not to be associated with intake of B-group vitamins or methionine, and findings were consistent across tumour subtypes and across demographic and lifestyle characteristics of the participants. A potential interaction between vitamin B1 and alcohol drinking was observed (all participants: HR per 1 SD=0.99 (0.91-1.09), never drinkers: HR=0.81 (0.69-0.97), P-interaction=0.02), which needs to be confirmed by other studies. Our findings do not indicate that dietary intake of nutrients involved in one-carbon metabolism are associated with UCC risk. This article is protected by copyright. All rights reserved.

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