[Preoperative adjuvant therapy for primary malignant bone tumors]

In primary bone sarcomas, the efficacy of chemotherapy varies according to the histological types. Prognoses are poor in patients with osteosarcoma or Ewing's sarcoma, when surgery alone is performed. However, because these sarcomas are chemosensitive, their prognoses have been improved with adjuvant chemotherapy. Nowadays, in highgrade bone sarcomas, especially in osteosarcoma, Ewing.s sarcoma and malignant fibrous histiocytoma of bone, adjuvant chemotherapy including neoadjuvant or preoperative chemotherapy is usually performed. The purpose of the neoadjuvant chemotherapy is (I) to prevent distant metastases, (II) to reduce the size of the primary tumor and (III) to evaluate the efficacy of the chemotherapeutic agents. Reducing the tumor size facilitates easier excision with less risk of local recurrence. In addition, not only limb-saving but also function-preserving surgery is made possible. Evaluating the efficacy of the chemotherapeutic agents in preoperative chemotherapy facilitates rational selection of postoperative chemotherapeutic agents. Several kinds of anticancer agents are used, and many authors have reported various kinds of protocols and their clinical results. Commonly used drugs include adriamycin, ifosfamide, cisplatin, methotrexate and vincristine in osteosarcoma, and vincristine, adriamycin, cyclophosphamide, ifosfamide, actinomycin-D and etoposide in Ewing's sarcoma. In contrast, chondrosarcomas are chemoresistant, and chemotherapy is rarely performed. Low-grade bone sarcomas, e. g., parosteal osteosarcoma, central low-grade osteosarcoma, are well cured only by surgical excision, and adjuvant chemotherapy is not performed for these low-grade sarcomas. To enhance the efficacy of preoperative chemotherapy, various modalities have been used e. g., intraarterial infusion, caffeine-assisted chemotherapy, and local perfusion with hyperthermia. Good clinical results have been reported.