Indication of adjuvant radiotherapy in Carcinoma Endometrium are all except :

Pelvic postoperative radiotherapy (external) in a dose of 6000 cGy over a 6-week period is also recommended in highrisk cases such as undifferentiated tumour, myometrial infiltration, pelvic node involvement, and in serous, clear cell adenosquamous carcinoma. The postoperative radiotherapy is required in Stages IA (Grade 3), IA2, IB and II. Chemo-radiation yields a better effect. Reference : Shaw's Textbook of Gynaecology 16th edition page no 512