Mesenchymal chondrosarcoma: A Japanese Musculoskeletal Oncology Group (JMOG) study on 57 patients

Background: This study aimed to elucidate the clinical features and prognostic factors of mesenchymal chondrosarcoma (MCS) and investigate optimal treatment strategies. Methods: Data from 57 patients with MCS were collected from a Japanese Musculoskeletal Oncology Group (JMOG) and retrospectively analyzed. Results: Data from 29 males and 28 females were collected. Primary tumor sites were the head and neck (7 patients), trunk (35 patients), and extremities (15 patients). The tumors originating in the trunk were significantly associated with a worse OS compared with those originating at the other sites in all patients and those with localized disease (P = 0.020 and P = 0.019, respectively). In patients with localized disease, the tumors originating in the head and neck were significantly associated with better OS and MFS compared with those originating in the trunk (P = 0.024 and P = 0.014, respectively). Positive surgical margin was significantly correlated with the worse LRFS (P = 0.018). Adjuvant chemotherapy exhibited a clear trend toward improved OS when MCS was localized in the trunk or extremities (P = 0.057). Conclusions: Adequate surgery is considered to be the mainstay of treatment for localized MCS. Prognosis was different depending on the site of tumor origin.