CYP19A1 and breast cancer: The endocrine therapy for breast cancer has made great progress with the development of selective estrogen receptor modulators (SERMs), aromatase inhibitors (AIs), selective estrogen receptor degraders (SERDs), and estrogen receptor PROTAC degrader.[10, 11, 12] Though the 5‐year survival rate of ER+ breast cancer is impressive, however, there are still around 30% of patients undergo endocrine therapy drug resistance, recurrence, and metastasis.