Efficacy of adjuvant radiotherapy in non-extremity soft tissue sarcoma with moderate chemosensitivity.

PURPOSE: Soft tissue sarcoma (STS) is a rare and heterogeneous cancer with over 50 known subtypes. It is difficult to understand the role of adjuvant treatment in STS. We aimed to determine the benefits of adjuvant treatment for a rare STS subset: non- extremity STS with moderate chemosensitivity.

MATERIALS AND METHODS: We reviewed medical records from Pusan National University Hospital and Kosin University Gospel Hospital, which had detailed pathological reports on patients diagnosed between 2006 and 2016. The most important inclusion criterion was resection with curative intent. We grouped STS by chemosensitivity based on reported data and analyzed non- extremity STS with moderate chemosensitivity.

RESULTS: We investigated 142 patients with 20 pathological subtypes of STS. Eighty-six patients had extremity STS and 56 had non- extremity STS. Thirty-eight of 56 patients were categorized as having moderate chemosensitivity. Seventeen of 38 patients (44.7%) received adjuvant radiotherapy and 14 (36.8%) received adjuvant chemotherapy. A log-rank test showed longer disease-free survival (DFS) in the adjuvant radiotherapy group than in the group treated without adjuvant radiotherapy (not reached vs. 1.468 years, p = 0.037). Multivariate Cox proportional hazard analysis, with covariates including age, stage, resection margin, adjuvant chemotherapy, and adjuvant radiotherapy, revealed that adjuvant radiotherapy was associated with longer DFS (odds ratio = 0.369, p = 0.045). Overall survival was not correlated with adjuvant radiotherapy.

CONCLUSION: Adjuvant radiotherapy may be associated with longer DFS in patients with non-extremity STS with moderate chemosensitivity.