High-grade endometrial stromal sarcoma versus undifferentiated uterine sarcoma: a Turkish uterine sarcoma group study-001.

UUS has a more aggressive behavior than HGESS. While no significant predictor of prognosis was found for UUS, LVSI is the sole independent prognostic factor for HGESS, with patients 9.3 times more likely to experience refractory/progressive disease, recurrence or death.