Abstract
Malignant giant cell tumor (GCT) of bone is a rare tumor with debilitating consequences. Patients with GCT of bone typically present with mechanical difficulty and pain as a result of bone destruction and are at an increased risk for fracture. Because of its unusual occurrence, little is known about the epidemiology of malignant GCT of bone. This report offers the first reliable population-based estimates of incidence, patient demographics, treatment course and survival for malignancy in GCT of bone in the United States. Using data from the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) program, we estimated the overall incidence and determinants of survival among patients diagnosed with malignant GCT of bone from 1975-2004. Cox proportional hazards regression was used to evaluate demographic and clinical determinants of survival among malignant GCT cases. Based on analyses of 117 malignant GCT cases, the estimated annual incidence in the United States was 1.6 per 10,000,000 persons per year. Incidence was highest among adults aged 20 to 44 years (2.4 per 10,000,000 per year) and most patients were diagnosed with localized (31.6%) or regional (29.9%) disease compared to distant disease (16.2%). Approximately 85% of patients survived at least 5 years, with survival poorest among older patients and those with evidence of distant metastases at time of diagnosis. The current study represents the largest systematic investigation examining the occurrence and distribution of malignancy in GCT of bone in the general U.S. population. We confirm its rare occurrence and suggest that age and stage at diagnosis are strongly associated with long-term survival.