Early Assessment of Therapeutic Response using FDG PET in Small Cell Lung Cancer

Abstract

We evaluated the ability of 2-deoxy-2-(18)F-fluoro-D-glucose (FDG) positron emission tomography (PET) in the early assessment of therapeutic response in patients with small cell lung cancer (SCLC). FDG PET studies were performed before (baseline PET), after the first cycle of chemotherapy (early PET), and after completion of therapy (final PET) in 12 patients with SCLC. The standardized uptake value (SUVmax) was measured. Metabolic response was defined as a reduction in SUVmax of more than 20% on the early PET, compared with the baseline PET. Tumor response after completion of therapy was evaluated according to the Response Evaluation Criteria in Solid Tumors (RECIST). Eleven patients were classified as metabolic responders and had a mean (+/-SD) reduction in SUVmax of 57.9 +/- 10.3%. The remaining one patient was classified as a metabolic nonresponder with a reduction in SUVmax of 13.5%. In all patients, metabolic response after the first cycle of chemotherapy was associated with subsequent response according to RECIST. FDG PET has the potential to identify the therapeutic response in patients with SCLC as early as after the first cycle of chemotherapy.