Neoadjuvant chemotherapy for high-grade central osteosarcoma of the extremity. Histologic response to preoperative chemotherapy correlates with histologic subtype of the tumor

BACKGROUND: In primary central high-grade osteosarcoma, a number of distinct subtypes have been identified, but little is known about the response to chemotherapy. METHODS: The authors investigated whether the subtypes correlated with histologic response to chemotherapy in 1058 patients with osteosarcoma of the extremities who were treated with neoadjuvant chemotherapy over the last 20 years. The tumors were classified as osteoblastic (70%), chondroblastic (13%), fibroblastic (9%), and telangiectatic (6%). At diagnosis, 911 patients had localized disease and 147 had resectable lung metastases. RESULTS: The response to preoperative chemotherapy was good (90% or more tumor necrosis) in 59% of patients and poor (< 90% tumor necrosis) in 41% of patients. The rate of good responses was significantly higher (P = 0.0001) in the fibroblastic (83%) and telangiectatic (80%) tumors and significantly lower in chondroblastic tumors (43%). Prognosis was significantly correlated with the histologic subtypes. The 5-year overall survival rate was significantly higher (P = 0.0001) in fibroblastic (83%) and telangiectatic (75%) tumors than in osteoblastic (62%) and chondroblastic (60%) tumors. In all subtypes, except for the chondroblastic subtype, the 5-year overall survival rate was significantly higher (P = 0.0001) in good responders P = 0.0001 (68%) than in poor responders (52%). CONCLUSIONS: The authors concluded that the histologic subtype of primary central high-grade osteosarcoma of the extremity was strictly correlated with histologic response to chemotherapy and probably, as a consequence, also with prognosis. Further studies are needed to establish whether these results justify a specific therapeutic approach based on the histologic subtype of the tumor.