This study is to investigate the association of fibroblast growth factor receptor 2 (FGFR2) rs2981582, trinucleotide-repeat-containing 9 (TNRC9) rs3803662, rs12443621, and leukocyte-specific protein 1 (LSP1) rs3817198 polymorphisms with breast cancer and mammographic density in Han Chinese population. The gene discussed is TOX3; the disease is breast carcinoma.