Stage IA vs. IB endometrial stromal sarcoma: does the new staging system predict survival?

To determine the correlation of the new FIGO staging system with survival in stage I patients with low-grade and high-grade endometrial stromal sarcomas.

Data were extracted from the Surveillance, Epidemiology, and End Results database between 1988 and 2005. Kaplan-Meier log rank and Cox proportional hazards models were used for survival analysis and to identify possible predictors for survival.

The identified cohort included 464 women, 310 (67%) low-grade endometrial stromal sarcoma, 96 (21%) high-grade endometrial stromal sarcoma, and 58 (12%) unclassified endometrial stromal sarcoma. Among low-grade and high-grade endometrial stromal sarcomas, there was no significant demographic or clinico-pathologic difference between stages IA and IB. The 5-year overall survival was worse in high-grade endometrial stromal sarcoma than low-grade endometrial stromal sarcoma (45.4% vs. 97.2%, p<0.001). The difference in 5-year overall survival among women with low-grade endometrial stromal sarcoma between stages IA and IB was significant (100% vs. 93.5%, p=0.003), but not among women with high-grade endometrial stromal sarcoma (51.4% vs. 43.5%, p=0.27). Although age (p=0.001), race (p=0.005), and stage (p=0.004) were all significant prognostic factors in low-grade endometrial stromal sarcoma, only cervical involvement (p=0.02) was a significant predictor in high-grade endometrial stromal sarcoma.

The new staging system is appropriate for risk stratification in low-grade endometrial stromal sarcoma. The prognosis in high-grade endometrial stromal sarcoma seems to be most influenced by the presence of cervical involvement and not by tumor size as the staging criteria would suggest.