Is [F-18]-fluorodeoxy-D-glucose positron emission tomography of value in the management of patients with craniofacial bone sarcomas undergoing neo-adjuvant treatment?

We evaluated the role of ¹⁸FDG PET/CT used to assess response to preoperative chemotherapy in patients with primary craniofacial bone sarcomas.

Fourteen 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.

The 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).

¹⁸FDG 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.