In March 2023, the patient developed hematuria and was diagnosed with bladder metastasis based on cystoscopy (Figure 3B) and biopsy, with IHC findings indicating breast cancer origin (Figure 3C): ER 90% (1-2+), PR <1%, HER2 (c-erbB-2) 2+, Ki-67 35%, AR 95% (3+), GATA-3+, CK (AE1/AE3)+, and P63-. The gene discussed is ESR1; the disease is breast carcinoma.