Researchers from the University of Texas M.D. Anderson Cancer Center in Houston have discovered that FDG PET/CT can be used as a prognostic indicator for progression-free survival, overall survival and tumor necrosis in osteosarcoma.
The aim of the study, published in the March issue of the Journal of Nuclear Medicine, was to retrospectively evaluate whether maximum standardized uptake value (SUVmax), total lesion gylcolysis (TLG), or change therein using 18F-FDG PET/CT performed before and after initial chemotherapy were indicators of patient outcome.
The researchers reviewed 31 consecutive patients who underwent 18F-FDG PET/CT before and after chemotherapy, followed by tumor resection. Univariate Cox regression was used to analyze for relationships between covariates of interest (SUVmax before and after chemotherapy, change in SUVmax, TLG before and after chemotherapy, change in TLG and tumor necrosis) and progression-free and overall survival. Logistic regression was used to evaluate tumor necrosis.
The study is the first "to meaningfully evaluate TLG in patients with osteosarcoma. Unlike SUV, which is a measurement of metabolic activity per body weight, TLG evaluates metabolic activity throughout the volume of the tumor (SUVavg multiplied by tumor volume) above a minimum threshold designed to exclude background activity," the authors wrote.
High SUVmax before and after chemotherapy was associated with worse progression-free survival, the researchers said. They reported that good overall and progression-free survival was associated with a tumor necrosis greater than 90 percent. A tumor necrosis greater than 90 percent was most strongly associated with a decrease in SUVmax.
"Our study has shown that 18F-FDG PET/CT is a predictor of progression-free survival, overall survival, and tumor necrosis in osteosarcoma, whether SUVmax or TLG is used," the authors wrote. "Although the results suggest that SUVmax is a stronger indicator than is TLG, we are awaiting large prospective studies to more fully assess which of the 2 methods of measuring 18F-FDG uptake is the optimal predictor of survival."