Adjuvant chemotherapy of high-grade osteosarcoma of the extremity. Updated results of the Multi-Institutional Osteosarcoma Study.

The Multi-Institutional Osteosarcoma Study (MIOS) was designed to determine whether intensive multiagent adjuvant chemotherapy improves the outcome of patients with nonmetastatic high-grade osteosarcoma of the extremity as compared with concurrent controls. After definitive surgery of the primary tumor, patients were randomly assigned to immediate adjuvant chemotherapy or to observation without adjuvant treatment. Updated results of this trial indicate that the projected six-year event-free survival for the control group is 11% compared to 61% for the chemotherapy group (p less than 0.001). Similar results were observed in patients who declined randomization but who were followed according to the treatment arms of the protocol. When randomized and nonrandomized patients are pooled according to assigned treatment, a survival advantage favoring those patients treated with immediate adjuvant chemotherapy is apparent. An analysis of prognostic factors among patients receiving immediate adjuvant chemotherapy reveals that elevation of the serum lactic dehydrogenase at diagnosis is the factor most predictive of adverse outcome. Location of the primary site in the tibia confers a favorable prognosis. The authors conclude that the natural history of high-grade osteosarcoma of the extremity has not changed over the past two decades. The administration of immediate adjuvant chemotherapy has a significant favorable impact on event-free survival and should be recommended for all such patients.