It has been hypothesized that ER-negative and perhaps PR-negative breast tumors, which result from hypermethylation of the promoter region of ER and PR,8 are linked to low intake of B vitamins.7 We thus examined the association between vitamin B6 intake and breast cancer risk stratified by the ER and PR status of breast tumors (Table 5). This evidence concerns the gene ESR1 and breast cancer.