FIGO 1988 versus 2009 staging for endometrial carcinoma: a comparative study on prediction of survival and stage distribution according to histologic subtype

OBJECTIVE: The surgical staging system for endometrial carcinoma developed by International Federation of Gynecology and Obstetrics (FIGO) in 1988 was revised in 2009. Given the importance of continuous validation of the prognostic performance of staging systems, we analyzed the disease specific survival for patients with endometrial carcinoma using FIGO 1988 and 2009 systems. Further, the stage distribution of endometrioid and nonendometrioid carcinomas was studied. METHODS: Eight hundred twenty-one women with endometrial carcinoma were retrospectively staged using FIGO 1988 and 2009 systems. RESULTS: FIGO 1988 IC was associated with an inferior survival compared with IA-IB. Survival overlapped for 1988 IA and IB, for 1988 IC and IIA, and for 2009 IB and II. FIGO 2009 IA-II patients with negative peritoneal cytology had a superior survival compared with 1988 IIIA patients with positive cytology only. The survival was similar for 1988 IIIA with positive cytology only and for 2009 IIIA. Cox proportional hazards model recognized grade 3 endometrioid and nonendometrioid histology, tumor spread beyond the uterine corpus and cervix, and positive peritoneal cytology as significant predictors of death. Among 2009 IIIC substages, the proportion of IIIC2 tumors was higher for nonendometrioid than for endometrioid carcinomas (p=0.003). CONCLUSION: Stage I with deep myometrial invasion and stage II endometrial carcinoma seem to have similar survival outcomes. Although positive peritoneal cytology does not alter the stage according to the FIGO 2009 system, it should be considered a poor prognostic sign. The high proportion of nonendometrioid carcinomas in the stage IIIC2 category may reflect different patterns of retroperitoneal spread among tumors with different histologic subtypes.