Abstract
INTRODUCTION: Mesenchymal chondrosarcoma (MCS) is a malignant, biphasic, high-grade, primitive mesenchymal tumor that has a well-differentiated, organized hyaline component. MCS has a poor prognosis, and treatment recommended for localized MCS is based on wide resection while controversy remains regarding the efficacy of adjuvant chemotherapy and radiotherapy. In this study, we aimed to investigate the prognostic factors of MCS, especially the efficacy of adjuvant chemotherapy and radiotherapy for localized MCS. METHODS: Eighty patients with MCS pathologically diagnosed between 2006 and 2022 from the Japanese National Bone and Soft Tissue Tumor Registry database were analyzed retrospectively. RESULTS: Patients with distant metastases at presentation (n = 23) had significantly shorter survival than those without (n = 57) (5-year disease-specific survival 19.9% [95% confidence interval (CI): 5.6-50.7] vs. 79.8% [95% CI: 62.4-90.4]; p < 0.0001). In the group without distant metastasis at presentation (n = 57), R1 or R2 surgical margin was a risk factor for unfavorable local recurrence (hazard ratio (HR): 17.44 [95% CI: 2.17-139.98]; p = 0.007). There was no correlation between adjuvant radiotherapy and local recurrence rate (HR 5.18 [95% CI: 0.99-27.12]; p = 0.051). R1 or R2 surgical margin was a risk factor for unfavorable disease-specific survival (HR 17.42 [95% CI: 2.18-138.90]; p = 0.007). There was no correlation between adjuvant chemotherapy and disease-specific survival (HR 0.99 [95% CI: 0.28-3.47]; p = 0.990). DISCUSSION: Patients with MCS and distant metastases at presentation have a poor prognosis, and wide resection is important for the treatment of localized MCS. The efficacy of adjuvant radiotherapy and chemotherapy could not be determined because of the small number of patients.