[Indication of chemotherapy according to histological type of musculoskeletal sarcomas]

In high-grade musculoskeletal sarcomas, adjuvant chemotherapy is often performed to prevent distant metastases. As the efficacy of chemotherapy varies according to the histological type of sarcoma, its indication is determined according to the histological type and the stage. Prognoses are poor in patients with osteosarcoma, Ewing's sarcoma, or rhabdomyosarcoma, when surgery alone is performed. However, because these sarcomas are chemosensitive, their prognoses are improved with adjuvant chemotherapy, so it is absolutely necessary. Drugs commonly used for osteosarcoma include adriamycin, cisplatin, methotrexate, vincristine, and ifosfamide. For Ewing's sarcoma and rhabdomyosarcoma, vincristine, actinomycin-D, cyclophosphamide, etoposide, and ifosfamide are commonly used. On the other hand, the efficacy of chemotherapy is unclear in most of the non-round cell sarcomas, e. g., malignant fibrous histiocytoma, pleomorphic liposarcoma, and leiomyosarcoma, so adjuvant chemotherapy is relatively indicated and often performed preoperatively. The efficacy is evaluated by reduction of the tumor volume as a surrogate marker. Postoperative chemotherapy is performed when the preoperative chemotherapy is effective. Nowadays, several kinds of antitumor agents are usually used for non-round cell sarcomas, and many authors have reported various kinds of regimens and their clinical results. Among them, the key drugs are adriamycin and ifosfamide. Recently, taxanes and gemcitabine are sometimes used. For chemoresistant sarcomas, e. g., chondrosarcoma, chordoma, alveolar soft part sarcoma, chemotherapy is rarely indicated, even if the tumor is histologically high grade and large. Low-grade musculoskeletal sarcomas, e. g., low-grade chondrosarcoma, central low-grade osteosarcoma, parosteal osteosarcoma, well-differentiated liposarcoma, and dermatofibrosarcoma protuberans, are well cured only by surgical excision, and adjuvant chemotherapy is therefore not indicated. Superficially-located, small-size non-round cell sarcomas, even though histologically high grade, are well healed only by surgical excision, and adjuvant chemotherapy is rarely indicated.