FDG-PET Predicts Prognosis in Primary Osteosarcoma

LOS ANGELES—A retrospective study indicates that 18F-fluorodeoxyglu-cose (FDG)-PET may be a good tool for predicting osteosarcoma patients’ response to chemotherapy, said Christiane Franzius, MD, and colleagues from the Department of Nuclear Medicine, University of Munster, Germany.

Dr. Franzius presented the results at the 49th Annual Meeting of the Society of Nuclear Medicine (abstract 128).

In the study, the researchers monitored FDG uptake in 29 patients with primary osteosarcoma (ages 5 to 41) before treatment. FDG uptake was quantified as high or low using average and maximum tumor/nontumor ratios (T/NTav, T/NTmax). The patients then received chemotherapy and underwent surgery of their primary tumor site.

At a median of 28 months after treatment (range, 7 to 72 months), the patients with higher initial FDG uptake in their tumor had a poorer response to treatment, measured histologically, and a poorer prognosis.

During follow-up, nine patients relapsed and six died of the disease. Both overall and event-free survival were significantly better in patients with low FDG T/NTmax values (less than the median) than in those with high FDG T/NTmax values (greater than or equal to the median).

"The prognosis for a patient with osteosarcoma is always dependent on the therapy they undergo," Dr. Franzius said. "PET identifies patients at first diagnosis of the disease who may have a poor prognosis with the therapy usually prescribed. These patients can then be treated more aggressively. In additional studies, we hope to determine whether such therapy intensification actually improves outcomes for patients identified at diagnosis with high FDG uptake on PET."

In an interview with ONI, Dr. Franzius said that the researchers plan to study a large group of patients with osteosarcoma prospectively to confirm the results of the current study.

"Furthermore," Dr. Franzius said, "we will study a group of patients with Ewing’s sarcoma to evaluate whether the initial FDG uptake has the same prognostic impact in this tumor entity as shown in osteosarcoma."