Association of vitamin D receptor gene polymorphism with sporadic breast cancer in Taiwanese patients

Purpose. Previous reports have suggested that polymorphism in the vitamin D receptor (VDR) gene is associated with sporadic breast cancer, but there is controversy among different authors and ethnic groups. The purpose of this study was to determine whether polymorphism in the VDR gene might also influence breast cancer risk in Taiwan, a country with a low incidence of breast cancer. Methods. Polymorphisms in the end of the VDR gene were genotyped for 34 Taiwanese women with sporadic breast cancer, 46 with benign breast tumors and 169 cancer-free female cohort controls. Results. The ApaI, TaqI, and BsmI polymorphisms in the 3' end of the VDR gene were associated with breast cancer risk, with a trend for increasing risk with increased numbers of BsmI (B) under bar alleles and ApaI (AA) double under bar genotypes. When the allele frequencies of BsmI polymorphism were compared among the three populations, a significant difference was observed (chi(2) = 13.684, df = 4, p = 0.0084). The OR of the (Aa) under bar genotype was 0.333 (95% CI = 0.114-0.978) and that of the (aa) under bar genotype was 0.515 (95% C1 = 0.190-1.398). These data indicate that the (AA) under bar genotype may be associated with an increased risk of breast cancer, while the (Aa) under bar genotype tends to be associated with decreased risk. The TaqI polymorphism was not associated with breast cancer risk in this study. Conclusion. These results suggest that polymorphic variation in or near the 3' end of the VDR gene may influence breast cancer risk in Taiwanese women and justifies further investigation of the role of VDR for sporadic breast cancer in low-incidence areas. These findings also should help when designing targeted therapy.