Secondary Malignancy in Giant Cell Tumor: A Single-Center Study

Giant cell tumor of bone (GCTB) uncommonly undergoes sarcomatous transformation. Secondary malignancy in giant cell tumor (MGCT) develops at the prior treatment site, and is associated with radiotherapy and dismal prognosis. The objective of this study is to investigate the clinicopathological characteristics of MGCT patients. We reviewed medical records of patients with secondary MGCT. Twelve patients were analyzed including six females and six males, with a median age of 42.5 years. Benign recurrence occurred in five GCTB patients, who were not treated with radiotherapy. No pulmonary implants were observed. The median latency was 63 months. Nine patients were AJCC stage IIB, and three were stage IVA. The median follow-up period after malignant transformation was 62.5 months. Five patients developed local recurrence and six had metastasis. Five-year overall, recurrence- and metastasis-free survivals were 61.9%, 66.7% and 58.3%. The local recurrence of GCTB was a potential factor for metastasis-free survival. Difference in overall survival according to benign local recurrence was almost significant. In our series, the occurrence of secondary MGCT did not follow radiotherapy, contrary to the Western literature. The prognosis was better than the findings reported in previous studies. The local recurrence of benign GCTB could reflect the prognosis of MGCT.