Prognostic factors and impact of adjuvant treatments on local and metastatic relapse of soft-tissue sarcoma patients in the competing risks setting

BACKGROUND In the medical literature many analyses of outcomes of sarcoma patients were performed without regard to the problem of "competing risks." METHODS We analyzed local relapse-free and metastasis-free survival in a population of 3255 adult patients with a primary soft-tissue sarcoma (STS) included in the French Sarcoma Group database. Cumulative incidence of local and metastatic relapse was estimated by accounting for death as a competing event. RESULTS On multivariate analysis, age, tumor site, histological subtype, and grade were independent adverse prognostic factors for local relapse, whereas tumor depth and size had no influence. Histological subtype, tumor depth, tumor size, and grade were independent adverse prognostic factors for metastatic relapse. Despite a higher incidence of competing deaths in patients managed with adjuvant radiotherapy than in patients not receiving radiotherapy, adjuvant radiotherapy was associated with a significant benefit in terms of local relapse-free survival. Despite a similar cumulative incidence of competing deaths in patients with grade 2 and grade 3 disease, we found that the benefit of adjuvant chemotherapy was present only in patients with grade 3 and not in patients with grade 2 disease. CONCLUSIONS In the setting of competing risks, tumor biology reflected by histological grade is a crucial predictor of local relapse, whereas tumor depth and size have poor if any influence. Grade could also predict the benefit of adjuvant chemotherapy in patients with STS.