Validation of Tumor Size as Staging Variable in the Revised International Federation of Gynecology and Obstetrics Stage I Leiomyosarcoma

Abstract

Tumor size has been introduced as a staging variable in the 2008 International Federation of Gynecology and Obstetrics (FIGO) staging system for stage I leiomyosarcoma. In the prior 1988 FIGO staging system, leiomyosarcoma used the same staging criteria as endometrial cancer including cervical involvement. In this large population-based study, we validate the use of tumor size for purposes of risk stratification among stage I leiomyosarcoma patients. 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 819 women: 158 (19.3%), 2008 FIGO stage IA and 661 (80.7%), 2008 FIGO stage IB leiomyosarcoma. The 5-year overall survival rate was better in stage IA than in stage IB leiomyosarcoma (76.6% vs 48.4%, P < 0.001). Similarly, the 5-year overall survival rates were significantly different (P < 0.001) among women with different tumor size categories: 5 cm or smaller, 5.1 to 10 cm, and larger than 10 cm (76.6%, 52.9%, and 41.9%, respectively). The difference in 5-year overall survival rates between women with and without cervical involvement was significant (28.5% vs 55.3%, P = 0.014). Although age (P < 0.001), cervical involvement (P = 0.014), tumor grade (P < 0.001), tumor size (P < 0.001), performance of salpingo-oophorectomy (P = 0.001), and stage (P < 0.001) were all significant prognostic factors on univariate analysis, only age (P = 0.007), tumor size (P < 0.001), tumor grade (P < 0.001), and performance of salpingo-oophorectomy (P = 0.02) were significant predictors on multivariate analysis. Variables not found significant on univariate analysis (hence excluded from the Cox model) included lymphadenectomy, radiation, and race. The new staging system using tumor size is better for risk stratification in stage I leiomyosarcoma compared with the 1988 FIGO staging system of endometrial cancer.