Prediction of therapy outcome in patients with soft tissue sarcoma receiving neoadjuvant chemotherapy using dynamic FDG studies

Objectives To evaluate the FDG metabolism in patients (pts.) with soft-tissue sarcomas receiving neoadjuvant chemotherapy with respect to prediction of therapy outcome.

Methods The ongoing evaluation includes 31 pts. with non-metastatic soft-tissue sarcomas who were treated with pre-operative chemotherapy consisting of etoposide, ifosfamide and doxorubicin (EIA regimen, 4 cycles). Pts. were examined prior to onset of therapy and after completion of the first cycle of EIA using dynamic PET. Histopathological response served for reference and is available for 20/31 pts. Response was defined as <5% viable tumor tissue in the resected tumor tissue.

Results Median tumor SUV prior therapy was 3.62 SUV in comparison to 2.22 SUV after chemotherapy. We dichotomized the pts. into response (n=6) and non-response (n=14). We used discriminant analysis (DA) to classify the patients into the two response groups. DA revealed a correct classification rate of 71 % using kinetic data of first examination. The second examination revealed a higher correct classification rate of 80%. By combining kinetic data, SUV, vB, k1 and k3 of both examinations a CCR of 80% was achieved.

Conclusions On the basis of these results, kinetic FDG data of the first follow-up study after one cycle is helpful for the prediction of chemo-sensitivity in patients soft tissue sarcomas receiving neoadjuvant chemotherapy.