Folate metabolism genes, vegetable intake and renal cancer risk in central Europe

In a multicenter case-control study of renal cell carcinoma (RCC) conducted in central and eastern Europe, we reported a strong inverse association with high vegetable intake and RCC risk. The odds ratio (OR) for high compared to the lowest tertile of vegetable intake was OR = 0.67; (95% confidence interval (CI): 0.53-0.83; p-trend < 0.001). We hypothesized that variation in key folate metabolism genes may modify this association. Common variation in 5 folate metabolism genes (CBS: Ex9+33C > T (rs234706), Ex13 +41C > T (rs1801181), Ex18 -391 G > A (rs12613); MTHFR: A222V Ex5+79C > T (rs1801133), Ex8-62A > C (rs1801131); MTR: Ex26 20A > G (rs1805087), MTRR: Ex5+136 T > C (rs161870), and TYMS:IVS2-405 C > T (rs502396), Ex8+157 C > T (rs699517), Ex8+227 A > G (rs2790)) were analyzed among 1,097 RCC cases and 1,555 controls genotyped in this study. Having at least 1 variant T allele of MTHFR A222V was associated with higher RCC risk compared to those with 2 common (CC) alleles (OR = 1.44; 95% CI: 1.17-1.77; p = 0.001). After stratification by tertile of vegetable intake, the higher risk associated with the variant genotype was only observed in the low and medium tertiles (p-trend = 0.001), but not among those in the highest tertile (p-interaction = 0.22). The association remained robust after calculation of the false discovery rate (FDR = 0.05). Of the 3 TYMS SNPs examined, only the TYMS IVS2 -405 C (rs502396) variant was associated with a significantly lower risk compared to the common genotype (OR = 0.73; 95% CI: 0.57-0.93). Vegetable intake modified the association between all 3 TYMS SNPs and RCC risk (p-interaction < 0.04 for all). In summary, these findings suggest that common variation in MTHFR and TYMS genes may be associated with RCC risk, particularly when vegetable intake is low.