Table 1. Description of five risk recurrence systems.

RSS	Year	Number of patients	Criteria
PORTEC-1 (Creutzberg et al, 2000b)	2000	715	Low risk Endometrial adenocarcinoma stage Ia, grade 1  Intermediate risk Endometrial adenocarcinoma Stage I based on uterine factors Grade 1 histology and myometrial invasion of ⩾50% Grade 2 histology with any myometrial invasion Grade 3 histology with myometrial invasion <50%  High-intermediate risk Age >60 years with grade 1 or 2 histology and myometrial invasion >50% Age >60 with grade 3 histology and myometrial invasion <50%  High-risk Stage III–IV disease Uterine serous carcinoma or clear cell carcinoma of any stage
GOG-99 (Keys et al, 2004)	2004	382	Low risk Grade 1 or 2, endometrioid cancers confined to the endometrium stage IA  Low-intermediate risk Age ⩽50 years + ⩽2 pathologic risk factors Age 50–69 years + ⩽1 pathologic risk factor Age ⩾70 years + no pathologic risk factors (Risk factors (1) grade 2 or 3 histology; (2) positive lymphovascular space invasion; (3) myometrial invasion to outer 1/3)  High-intermediate risk (HIR) Any age + 3 pathologic risk factors Age 50–69 years + ⩾2 pathologic risk factors Age ⩾70 years + ⩾1 pathologic risk factor (Risk factors (1) grade 2 or 3 histology; (2) positive lymphovascular space invasion; (3) myometrial invasion to outer 1/3)  High-risk Stage III–IV disease, regardless of histology or grade Uterine serous carcinoma or clear cell carcinoma of any stage
SEPAL (Todo et al, 2010)	2010	671	Low risk Stage IA IB, endometrioid type, LVSI negative  Intermediate risk Stage IA grade 3 endometrioid adenocarcinoma; any grade of non-endometrioid carcinoma (serous adenocarcinoma, clear cell adenocarcinoma or other type of carcinoma), any LVSI Stage IB, grade 1–2 endometrioid adenocarcinoma, LVSI positive Stage IB, grade 3 endometrioid adenocarcinoma; any grade of non- endometrioid carcinoma (serous adenocarcinoma, clear cell adenocarcinoma or other type of carcinoma), any LVSI Stage IC, stage II, any grade, any LVSI  High risk Stage III–IV, any grade, any LVSI
ESMO (Colombo et al, 2013)	2013	—	Low risk Stage IA (grade 1 and grade 2) with endometrioid type  Intermediate risk Stage IA grade 3 with endometrioid type Stage IB (grade 1 and grade 2) with endometrioid type  High risk Stage IB grade 3 with endometrioid type All stages with non-endometrioid type
ESMO modified (Bendifallah et al, 2014)	2014	496	Low-risk ESMO/LVSI-  Low-risk ESMO/LVSI+  Intermediate-risk ESMO/LVSI-  Intermediate-risk ESMO/LVSI+  High-risk ESMO/LVSI-  High-risk ESMO/LVSI+

Abbreviations: ESMO=European Society for Medical Oncology; LVSI=lymphovascular space invasion.