FDG PET/CT imaging prior to osteosarcoma surgery and chemotherapy may be able to provide a clearer picture of patient risk and prognosis, according to a study published Aug. 15 in the Journal of Nuclear Medicine.

The study assessed quantitative FDG PET/CT, and particularly volumetric and metabolic parameters, as a predictor for metastases-free survival in patients with osteosarcoma of the extremities. Researchers led by Byung Hyun Byun, MD, from the department of nuclear medicine, Korea Cancer Center Hospital at the Korea Institute of Radiological and Medical Sciences in Seoul, Korea, found that FDG PET/CT could in fact tip off how patients responded to therapy. The ability to better select patients based on pretreatment imaging and estimated survival could potentially effect patient management and clinical decision-making.

“Most protocols used today use chemotherapy both before and after surgery in patients with osteosarcoma,” wrote Byun et al. “Delayed removal of tumor after neoadjuvant chemotherapy, however, may compromise clinical outcomes, and no convincing survival benefit from neoadjuvant chemotherapy has been proven. Risk-adapted therapy based on prognostic factors other than histologic response is hence needed to minimize the ineffective use of neoadjuvant chemotherapy.”

For this retrospective study, FDG PET/CT imaging data for 83 osteosarcoma patients who had undergone surgery and chemotherapy were reviewed with particular interest in metabolic tumor volume, total lesion glycolysis and maximum standardized uptake value. Tumor volumes also were assessed with MR images. Parametric data was analyzed and compared to histologic response to therapy after surgery.

Results of the research showed that the metabolic tumor volume based on a standardized uptake value threshold at 2.0 was an accurate predictor of poor response to therapy and risk of metastatic disease.

Stratified risk in patients with osteosarcoma is thought to be due to heterogeneity of disease. Quantitative FDG PET/CT with a focus on metabolic tumor volume allows a better diversity of disease and more prognostic value than post-therapy histologic testing alone. In tandem, FDG PET/CT and histologic evaluation could significantly alter the way high-risk patients are treated.

“On the basis of these combined criteria, high-risk patients with osteosarcoma may need to consider more aggressive systemic chemotherapy than low- or intermediate-risk patients because they more easily relapse and develop metastases.”