Oestrogen receptor gene (ESR1) amplification is frequent in endometrial carcinoma and its precursor lesions.

Oestrogen receptor alpha (ER) plays a critical, diverse and not fully understood role in endometrial carcinoma. Most endometrial carcinomas express ER and some of these tumours respond favourably to anti-oestrogen therapy. On the other hand, tamoxifen therapy constitutes a major risk factor for endometrial carcinoma development.