Mesenchymal chondrosarcoma of soft tissues and bone in children, adolescents, and young adults - Experiences of the CWS and COSS study groups

BACKGROUND. Mesenchymal chondrosarcoma (MCS) is a rare tumor with a strong tendency toward late recurrences leading to reported 10-year survival rates below 50%. The recommended treatment is resection with wide margins; the effectiveness of chemo- and radiotherapy remain poorly defined. As reports about MCS in young patients are scarce, treatment and outcomes of children/ adolescents/young adults in the CWS and COSS studies were investigated. METHODS. Since 1977, 15 of > 7000 CWS and COSS patients <= 25 years had a confirmed diagnosis of MCS. RESULTS. The median age was 16.6 (range, 1-25) and median follow-up 9.6 years (range, 1-22). Four MCS were osseous and 11 extraosseous. All but 1 patient had nonmetastatic disease. Tumor sites were head/neck (n = 6), paravertebral. (n = 3), pelvis (n = 3), limbs (n = 2), and kidney (n = 1). All tumors were resected, but only 8 completely. Thirteen individuals received chemotherapy, 6 were irradiated. Actuarial 10-year event-free and overall survival rates were 53% and 67%, respectively. Four recurrences occurred, all within 4 years from diagnosis (3 local, I combined; 2 of these in irradiated patients). One of these patients survived after surgery and radiation for local recurrence. Seven of 8 patients whose tumors were completely resected during primary treatment, but only 4 of 7 patients with incomplete surgery survived disease-free. CONCLUSIONS. This series of 15 MCS differs from others: the median age was young, most tumors were extraosseous, most patients received chemotherapy, and the outcome was better than published. Despite long-term follow-up, characteristic late metastatic recurrences were not observed. Treating MCS according to standard multimodal soft tissue/bone sarcoma regimens is proposed.