We therefore decided to use the data source provided by the Southern China Breast Cancer Genetics Study (SCBCGS) to evaluate the hypothesis that tumor intrinsic subtypes, in particular those defined jointly by the expression of ER, PR, HER2, and Ki-67, modify the association between breast cancer risk and the common FGFR2 intron-2 polymorphisms recently identified. This evidence concerns the gene ESR1 and breast carcinoma.