Herein we report a case of an 83-year-old female who developed choroidal metastasis, while on endocrine therapy with selective estrogen receptor modulator (SERM), tamoxifen, for ER positive, PR positive and HER2 negative primary breast carcinoma, which then regressed following first-line palliative systemic chemotherapy with palbociclib. This evidence concerns the gene ESR1 and breast carcinoma.