A 58-year-old postmenopausal woman from Delhi presents with vaginal bleeding for 3 months. She is obese (BMI 34 kg/m²), hypertensive, and diabetic. On examination, the uterus is normal size and mobile. Transvaginal ultrasound shows an endometrial thickness of 18 mm with heterogeneous echotexture. Endometrial biopsy reveals grade 1 endometrioid adenocarcinoma confined to the inner half of the myometrium. Staging MRI shows no evidence of cervical stromal invasion or extrauterine disease. What is the most appropriate next step in management?