Abstract
BackgroundWe evaluated the role of 18FDG PET/CT used to assess response to preoperative chemotherapy in patients with primary craniofacial bone sarcomas.MethodsFourteen patients with craniofacial bone sarcomas (13 osteosarcoma, 1 spindle cell sarcoma) were retrospectively evaluated. All patients received up to 6 cycles of preoperative chemotherapy followed by resection of the primary tumour. Response to treatment was assessed using MRI (RECIST criteria) and 18FDG PET/CT (EORTC guidelines), performed at least at baseline, after 2-4 cycles and pre-operatively.ResultsThe median baseline 18FDG PET/CT SUV was 10.2 (range 0-41); in 2 patients no uptake was detected. The preoperative 18FDG PET/CT, compared with the baseline, demonstrated a partial metabolic response in 7 patients (59%), complete metabolic response in 2 (16%) and stable metabolic disease in 3 (25%). In contrast, only two patients achieved a RECIST response on MRI: 10 (83%) had stable disease. One patient underwent early resection due to clinical progression after an initial response to treatment. This was confirmed by PET (SUV from 21 to 42) but not on MRI. Twelve of 14 patients (86%) had <90% histological necrosis in the resected tumour. At a median follow-up 23 months, 11 patients (79%) remain disease free, two had metastatic progression (14%) and 1 a local relapse (7%). The median DFS was 17 months. For those patients who achieved a response to preoperative 18FDG PET/CT the median DFS was 19 months (range: 1-66) compared with 3 months (range: 3-13) in those who did not (p = 0.01). In contrast, the median disease free survival (DFS) did not differ according to histological response (19 versus 17 months, >90% versus <90% necrosis, p = 0.45) or resection margins (19 months for R0 versus 18 months for R1, p = 0.2).Conclusion18FDG PET/CT is more reliable than standard imaging in evaluating response to neo-adjuvant chemotherapy in craniofacial bone sarcomas, changed management in one patient, and in this small series, correlated better with patient outcome than histological response and resection margins. These results warrant prospective validation in a larger cohort of patients.
Highlights
We evaluated the role of 18FDG [F-18]-fluorodeoxy-D-glucose positron emission tomography (PET/CT) used to assess response to preoperative chemotherapy in patients with primary craniofacial bone sarcomas
In 10 (86%) of 12 patients, magnetic resonance imaging (MRI) scans performed after 2-4 cycles and pre-operatively demonstrated stable disease according to RECIST criteria
The impact of 18FDG PET/CT in the management of craniofacial bone sarcomas (CBS) patients is exemplified by the clinical case represented in Figure 4, where disease stability demonstrated by the MRI scan may have led to the continuation of chemotherapy while the striking increase in the standard uptake value (SUV) detected by the 18FDG PET/CT determined the decision for early surgery
Summary
We evaluated the role of 18FDG PET/CT used to assess response to preoperative chemotherapy in patients with primary craniofacial bone sarcomas. Primary craniofacial bone sarcomas (CBS) are a group of rare tumours, accounting for less than 10% of all bone sarcomas and less than 1% of primary head and neck malignancies. They are usually diagnosed in older population than that affected by extremity bone sarcoma, with a median age at the time of diagnosis of 30 to 40 years, and a male to female ratio of around 1.7:1 [1,2,3]. Current available evidence suggests that negative surgical margins are the strongest predictor of survival for this disease and, unlike extremity osteosarcoma, the role of histological necrosis after preoperative chemotherapy is still to be determined [7]
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