Evaluation of chemotherapy response in pediatric bone sarcomas by [F-18]-fluorodeoxy-D-glucose positron emission...

Response to neoadjuvant chemotherapy is a significant prognostic factor for osteosarcoma (OS) and the Ewing sarcoma family of tumors (ESFT). Conventional radiographic imaging does not discriminate between responding and nonresponding osseous tumors. [F-18]-fluorodeoxy-D-glucose (FDG) positron emission tomography (PET) is a noninvasive imaging modality that accurately predicts histopathologic response in patients with various malignancies. To describe the FDG PET imaging characteristics and to determine the correlation between FDG PET imaging and chemotherapy response in children with bone sarcomas, we reviewed our single institution experience.

Thirty-three pediatric patients with OS or ESFT with osseous primary sites were evaluated by FDG PET. All patients received standard neoadjuvant chemotherapy. FDG PET standard uptake values before (SUV1) and after (SUV2) chemotherapy were analyzed and correlated with chemotherapy response assessed by histopathology in surgically excised tumors. Twenty-six patients had SUV1, SUV2, and surgical excision.

Although the mean SUV1 in children with OS or ESFT were similar (8.2. vs. 5.3, P = 0.13), mean SUV2 for OS patients was greater than the values for ESFT patients (3.3 vs. 1.5, P = 0.01). All ESFT patients and 28% of OS patients had a favorable histologic response to chemotherapy (>or= 90% necrosis). Combining ESFT and OS patients, both SUV2 and the ratio of SUV2 to SUV1 (SUV2:SUV1) were correlated with histologic response (P = 0.01 for both comparisons).

FDG PET evaluation of pediatric bone sarcomas demonstrated significant alteration in response to neoadjuvant chemotherapy. SUV2 and SUV2:SUV1 correlated with histopathologic assessment of response and potentially could be used as a noninvasive surrogate to predict response in patients.