A new computerized tomography classification to evaluate response to Denosumab in giant cell tumors in the extremities.

OBJECTIVES: The aim of this study was to describe the cohort of patients who have been treated with Denosumab as neoadjuvant therapy prior to surgery for aggressive giant cell tumor of bone in the extremities, to evaluate the radiological responses to Denosumab comparing Choi criteria and a newly described computerized tomography (CT) classification, and to evaluate the risk of local recurrence after intralesional curettage or radical excision. METHODS: We retrospectively evaluated 36 patients (20 females and 16 males; mean age at diagnosis 36 years (range, 18-64)) treated with neoadjuvant Denosumab therapy prior to surgery for aggressive giant cell tumor of bone in the extremities. The radiological responses to Denosumab treatment were analyzed on the preoperative images after the neoadjuvant course with the Choi criteria and with a newly proposed classification based on CT. All these images were independently reviewed by two of the researchers. Surgical intervention methods were noted and local recurrence rates were evaluated. The correlation between radiological response amount and local recurrence were analyzed for both Choi criteria and the new CT classification. RESULTS: Denosumab was administered for a mean of 21 weeks (range 7-133). Five patients also had a short postoperative course. According to Choi criteria there was a radiological response in 32 patients (89%), while the new CT classification identified responses in all the 36 patients (100%). The identification of changes after 7 weeks of treatment was higher using the CT classification compared to Choi criteria (p = 0.043 vs p = 0.462). The surgical interventions after Denosumab comprised curettage in 29 patients (74%) and resection in 7 (26%). Local recurrence was higher in patients managed with intralesional curettage than in those treated with en bloc resection (55.1% vs 0%, p < 0.001). At last follow up 19 patients (53%) required en bloc resections. Good responders to Denosumab (type 2C) had lower risk of local recurrence (p = 0.047) after either resection or curettage. CONCLUSION: The new CT classification evaluated more accurately the response to Denosumab. Our experience suggests that the requirement for radical bone resection remains high despite the use of Denosumab. LEVEL OF EVIDENCE: Level IV, Therapeutic Study.

Stanmore noninvasive extendible endoprosthesis in the treatment of bone sarcoma in the preadolescent.

AIMS: The aim of this study is to assess outcomes of patients ≤12 years who undergo Stanmore noninvasive extendible endoprosthetic replacement of the distal femur (DF NIEPR). PATIENTS AND METHODS: A total of 101 children (mean age 9.6 years) were included. All complications which required further surgery were recorded. Clinical and functional outcomes were evaluated with Musculoskeletal Tumor Society (MSTS) scores at a mean follow-up of 64 months (range 6-174). RESULTS: Thirty-one (30.7%) patients died at a mean of 33 months. Forty had prosthesis removed after a mean of 43 months (range, 7-103). Attaining of the full lengthening potential before skeletal maturity was the most frequent reason for revision surgery, particularly in those with smaller lengthening potential (P = 0.039). Implant survival rate for other causes was 61.7% at 5 years and 45.0% at 10 years. At final follow-up mean MSTS score was 26 (range, 13-29). Twenty-two (21.5%) patients had a final limb-length discrepancy (LLD) > 2 cm. CONCLUSIONS: DF NIEPR produces a good functional outcome, with the prevention of major LLD at skeletal maturity in the majority of the cases. We suggest patient selection criteria to account for the stage of the disease due to the high cost of the NIEPR, and high percentage requiring revision, and a 60% mortality rate in those patients presenting with distant disease burden.