26 January 2007
Vitamin D receptor genetic link to breast cancer depends on diet
Women with specific genetic variants in the vitamin D receptor (VDR) could cut their risk of breast cancer if they eat enough calcium, study findings suggest.
The researchers, led by Margorie McCullough from the American Cancer Society in Atlanta, Georgia, USA, believe the results suggest that dietary factors may modify the association between VDR genotype and breast cancer risk.
McCullough et al note that previous research inconsistently linked VDR polymorphisms with breast cancer risk, but "whether risk is influenced by polymorphisms in other vitamin D metabolism genes, and whether calcium or vitamin D modifies risk by genotype, has not been evaluated."
To explore the contribution of diet and genotype to breast cancer risk, the researchers compared data for 500 postmenopausal breast cancer patients and 500 healthy controls, matched for age, race/ethnicity, and date of blood collection, from the Cancer Prevention Study II.
They focused on single nucleotide polymorphisms in the VDR, 24-hydroxylase (CYP24A1), and vitamin D binding protein (GC) genes, along with a VDR poly(A) microsatellite. The women also completed a diet questionnaire and medical history at baseline, in 1992.
The findings revealed no links to incident breast cancer for any of the genotypes studied. However, an almost 40% reduced breast cancer risk was detected in women with the Bsm1 bb SNP who reported a greater than the median calcium intake (³ 902 mg/day), compared with those with Bb or BB genotypes and lower calcium intakes.
"Similar interactions were observed for Taq1 and the Poly(A) (LL) repeat," the team reports in the journal Breast Cancer Research.
McCollough et al conclude: "More research is needed to determine whether environmental factors, particularly diet, influence cancer risk by vitamin D pathway genotype."
Breast Cancer Res 2007; 9: R9
http://breast-cancer-research.com/co...df/bcr1642.pdf
Linear Mode
