18F-FDG PET use in the management of adrenocortical carcinoma

198 Objectives Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy. We evaluated the impact of 18F-FDG PET on ACC management. Methods This is a retrospective analysis of ACC patients seen in our institution between 1998 and 2012. Change in management before and after PET was assessed. Accuracy of PET was determined by using pathological reports, radiologic, and clinical data. Correlation between maximum standardized uptake value (SUVmax), tumor lesion glycolysis (TLG) and survival time, and predictive factors were evaluated. Results Out of 156 reviewed, 114 patients met eligibility criteria. For initial staging, 22 patients had PET scan including 17/22 with previously identified metastatic disease and 5/22 with borderline resectable disease; PET did not change clinical decisions in these patients. For restaging, 92 patients had 297 PET scans. 20.2 % of scans resulted in management changes. At initial diagnosis, PET sensitivity, specificity and accuracy were 100 %, 98.7%, and 99.0 % by each region. At recurrence, these were 97.1 %, 99.8%, and 99.4% respectively. At both initial diagnosis and recurrence, SUVmax and TLG did not correlate with survival time. Change in SUVmax following initial chemotherapy cycle did not predict response for chemotherapy. Multivariate analysis showed recurrence at multiple sites and failure of chemotherapy for recurrence were independent poor prognostic factors. Conclusions In a large cohort of ACC patients, PET use during restaging changed treatment plan in 1 out of 5 patients. PET also confirmed advanced disease in the small number of patients seen for initial management, but did not alter treatment. The overrepresentation of advanced cases (referral bias) limits our ability to fully assess the role of PET use in initial staging, but we find large impact of PET in response assessment and subsequent treatment decisions.