FDG PET scan strategies and long-term outcomes after first-line therapy in Hodgkin's Disease

BackgroundThe use of positron emission tomography with fluoro-deoxy-glucose (FDG PET) in Hodgkin's disease (HD) is continuing to expand worldwide, with response assessment after completion of therapy being its most widely utilized application. A positive scan has been associated with high relapse rates and disease progression.MethodsA decision analysis was performed to determine the long-term impact of FDG PET restaging both with and without computed tomography (CT) in terms of the 5-year progression-free survival (5yrPFS). Outcomes and utilities were based on published data. The first strategy involved CT restaging after first-line therapy, with or without subsequent FDG PET, while the second strategy used FDG PET scan alone. All positive test required histological examination. Upon histological confirmation of active lymphoma, patients were considered candidates for autologous transplantation and long-term outcomes were retrieved. The expected clinical benefit of the two strategies was calculated and depicted, along with the mean costs. One-way and two-way sensitivity analyses were performed to ensure the validity of the results.ResultsCT restaging plus FDG PET when residual mass is detected, results in a 2% benefit at 5yrPFS at baseline compared to FDG PET-alone restaging and remains positive for a wide range of probabilities. This strategy reduces the average cost by €1863 per patient, including costs of biopsy and autologous transplantation.ConclusionA more conservative approach that includes CT restaging after first-line therapy and FDG PET scan only on residual mass, is the preferred strategy in HD. Furthermore it appears to confer the maximal diagnostic yield along with a substantial reduction in the mean cost.