Positron emission tomography as a tool for early prediction of therapy outcome in patients with soft tissue sarcoma

Abstract

10572 Background: We used 2-deoxy-2-[18F]fluoro-D-glucose (FDG) positron emission tomography (PET) to evaluate the FDG uptake in patients with soft tissue sarcoma (STS). Treatment effect was assessed with regard to prediction of therapy outcome. Methods: The evaluation includes 27 patients with high risk STS receiving chemotherapy consisting of doxorubicin 75 mg/m2/day 1 and ifosfamide 1,500 mg/m2/day 1–4 (AI-G regimen) or etoposide 125 mg/m2/day 1+4, ifosfamide 1,500 mg/m2/day 1–4 and doxorubicin 50 mg/m2/day 1 (EIA regimen). Patients were examined using PET prior to onset of therapy and after completion of the first cycle of AI-G and after two cycles of EIA chemotherapy, respectively. Restaging according to RECIST criteria using computed tomography and magnetic resonance tomography was performed after six cycles of AI-G or four cycles of EIA chemotherapy and served for reference. Results: Clinical outcome of 27 evaluable patients was as follows: two patients with no evidence of disease, seven with partial remission, 14 with stable disease, and four patients with progressive disease. Median average standard uptake value (SUV) prior to onset of chemotherapy was 3.5 [range: 0 - 27.9] in comparison to 2.4 [range: 0 - 9.9] after chemotherapy treatment. Median SUVmax was 11.5 [range: 0 - 44.7] prior to chemotherapy in comparison to 7.9 [range: 0 - 21.7] following therapy. A significant difference of the progression-free survival for patients with a decrease in SUV (responders) in comparison to patients with an increase or stable SUV (non-responders) could be demonstrated (p = 0.0187). Conclusions: On the basis of these data, PET can be used as an easily measurable tool for early prediction of chemosensitivity of the tumor and moreover of the therapy outcome. Moreover, PET may even complement the existing RECIST criteria for tumor response evaluation. No significant financial relationships to disclose.