Utility of PET scan in predicting chemotherapeutic response in soft tissue sarcoma patients

Abstract

10021 Background: The response to chemotherapy in soft tissue sarcomas (STS) is often used to guide the further management of these neoplasms. The goal of this study was to determine if an overall metabolic response assessed by PET scan can be used to predict survival. Methods: Records of 12 STS patients (10m, 2f) who underwent pre- and post-chemotherapy PET scans were retrospectively renewed. PET scans were evaluated by a senior nuclear medicine physician and the response was compared to patient survival. Disease progression on PET was defined as a SUV increase in any lesion, appearance of new lesions, or presence of extended areas of disease activity during chemotherapy. A stable response was defined as a decrease in SUV <40% of the initial value of over half the lesions. A partial response was defined as a =40% decrease in SUV compared to the initial value in over half of the lesions. Patient survival was measured from the date of the post-treatment PET to the date of death or last follow-up. Results: Of the 12 patients, 6 had disease progression (all with metastases before treatment), 1 had stable disease with metastasis before treatment, and 5 had partial(4) or complete(1) responses of which 2 had metastases on presentation. The 6 patients who had progressive disease during treatment had a mean survival of 4 months (range 1.5–10.9 months, 0 alive at last follow-up). The patient with stable disease died at 13 months post-treatment. The 5 patients with partial to complete responses had a mean survival of 19 months (range 1.9–37.4, 3 alive). Patients with a partial or complete response had a longer mean survival than did patients with progression during chemotherapy, although this was not significant (p=0.49, Wilcoxon). When considering only patients with metastatic disease, the 3 patients without progression during chemotherapy had a longer mean survival (20 months, range 13–24, 1 alive) than the 6 patients with progression during chemotherapy, although this was not significant (p=0.17, Wilcoxon). Conclusions: A trend of decreased survival was seen in patients who had disease progression seen on PET during chemotherapy. Further studies with larger numbers of subjects need to be conducted to evaluate the correlation between the metabolic response to chemotherapy seen on PET to patient outcome in STS. [Table: see text]