Do Unresectable Giant Cell Tumors of Bone Treated With Denosumab Progress After Discontinuation of Treatment?

Abstract

BACKGROUND: Denosumab represents a valuable treatment option for unresectable giant cell tumors of the bone (GCTBs). However, no standardized protocols exist determining the length of administration, with few studies having been published on patients who reached the end of treatment. AIMS: To analyze the outcomes of patients diagnosed with GCTB and who had finished single treatment with denosumab. METHODS AND RESULTS: This is a multicenter, retrospective, descriptive study carried out in seven Spanish hospitals with multidisciplinary sarcoma and musculoskeletal tumor boards, between 2009 and 2019. Sixteen patients diagnosed with unresectable GCTBs and treated with denosumab who had reached the end of their treatment were recruited for the study and had been followed up for a minimum of 2 years. Fifty percent of patients discontinued denosumab after showing signs of tumor control. The disease remained stable in 69% of patients (n = 11), with a median recurrence-free survival time of 46 months (20-157 months) after being treated for a median period of 19 months (5-83 months). Four patients experienced local progression, and one presented multifocal progression. These five patients were treated for a median period of 46 months (14-76 months), with a median recurrence-free survival time of 9 months (5-25 months). CONCLUSION: The findings of the present study suggest that discontinuation of denosumab in patients with unresectable GCTB is not necessarily associated with the progression of the disease. Further research is needed to determine how long denosumab should be administered to minimize the risk of recurrence.