Methyl-deficient diets, methylated ER genes and breast cancer: an hypothesized association

Recent molecular studies show that ER-negative breast cancer results from the lack of ER gene transcription due to the methylation of the CpG island 5' to the gene. Because CpG island methylation is an early event in carcinogenesis and because methyl-deficient diets could result in CpG island methylation, it is relevant to postulate that methyl-deficient diets may be a risk factor for breast cancer with methylated ER genes (as opposed to the disease with unmethylated ER genes). This molecular-based etiologic hypothesis may facilitate epidemiological research on the relationship between breast cancer and diet that has been unclear until now.