Stage-Specific Outcomes of Patients With Uterine Leiomyosarcoma: A Comparison of the International Federation of Gynecology and Obstetrics and American Joint Committee on Cancer Staging Systems

Abstract

Uterine leiomyosarcoma (LMS) is staged by the modified International Federation of Gynecology and Obstetrics (FIGO) staging system for uterine cancer. We aimed to determine whether the American Joint Committee on Cancer (AJCC) soft tissue sarcoma (STS) staging system is more accurate in predicting progression-free survival (PFS) and overall survival (OS). Patients with uterine LMS who presented at our institution from 1982 to 2005 were staged retrospectively according to a modified FIGO staging system and the AJCC STS staging system. The predictive accuracy of the two staging systems was compared using concordance estimation. Two hundred nineteen patients had sufficient clinical and pathologic information to be staged under both systems; 132 patients were upstaged using the AJCC staging system, whereas only four were downstaged. Stage-specific PFS and OS rates for stages I, II, and III differed substantially between the two staging systems. In both systems, there was prognostic overlap between stages II and III. Thus, despite the marked stage-specific differences in 5-year PFS and OS rates for stages I, II, and III, both systems had similar concordance indices. Estimates of stage-specific PFS and OS for uterine LMS were altered substantially when using the AJCC versus FIGO staging system. Adjuvant treatment strategies should be tested in patients at substantial risk for disease progression and death. Neither the FIGO nor AJCC staging system is ideal for identifying such patients, suggesting a need for a uterine LMS-specific staging system to better target patients for trials of adjuvant therapies.