A 32 year-old woman with a familial history of LFS had presented with a right breast cancer (Scarff and Bloom and Richardson (SBR) grade 1 invasive ductal carcinoma (IDC), pT1N0, ER+, PR+, HER2-) that had been treated by a radical mastectomy and Tamoxifen in 2007. The gene discussed is ESR1; the disease is invasive ductal breast carcinoma.