Doxorubicin-based adjuvant chemotherapy in soft tissue sarcoma: pooled analysis of two STBSG-EORTC phase III clinical trials

Abstract

The EORTC-STBSG coordinated two large trials of adjuvant chemotherapy (CT) in localized high-grade soft tissue sarcoma (STS). Both studies failed to demonstrate any benefit on overall survival (OS). The aim of the analysis of these two trials was to identify subgroups of patients who may benefit from adjuvant CT. Individual patient data from two EORTC trials comparing doxorubicin-based CT to observation only in completely resected STS (large resection, R0/marginal resection, R1) were pooled. Prognostic factors were assessed by univariate and multivariate analyses. Patient outcomes were subsequently compared between the two groups of patients according to each analyzed factor. A total of 819 patients had been enrolled with a median follow-up of 8.2 years. Tumor size, high histological grade and R1 resection emerged as independent adverse prognostic factors for relapse-free survival (RFS) and OS. Adjuvant CT is an independent favorable prognostic factor for RFS but not for OS. A significant interaction between benefit of adjuvant CT and age, gender and R1 resection was observed for RFS and OS. Males and patients >40 years had a significantly better RFS in the treatment arms, while adjuvant CT was associated with a marginally worse OS in females and patients <40 years. Patients with R1 resection had a significantly better RFS and OS favoring adjuvant CT arms. Adjuvant CT is not associated with a better OS in young patients or in any pathology subgroup. Poor quality of initial surgery is the most important prognostic and predictive factor for utility of adjuvant CT in STS. Based on these data, we conclude that adjuvant CT for STS remains an investigational procedure and is not a routine standard of care.