ESR1 and breast cancer: Regarding the rs3803304 variant that presented risk associated with the development of breast cancer, the CG+GG combined genotypes were present in 11.4% of tumor stage T3-T4, in 20.9% of negative LN status, in 12.1% of negative ER status, in 14.3% of negative PR status, and in 24.2% of negative HER2 status.