18FDG positron emission tomography versus 67Ga scintigraphy as prognostic test during chemotherapy for non‐Hodgkin's lymphoma

Abstract

Summary. A prospective study was performed, comparing gallium scintigraphy (⁶⁷Ga) and positron emission tomography (PET) using fluorine‐18 fluorodeoxyglucose (¹⁸FDG), to monitor the response of aggressive non‐Hodgkin's lymphoma during treatment. ⁶⁷Ga and ¹⁸FDG scans were performed in 26 patients after two cycles of CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) therapy. The scans were reviewed independently by four experienced nuclear physicians, who were blinded for the alternative scan technique and follow‐up. Eleven out of 26 patients remained free from progression with a mean follow up of 25 ± 5 months, whereas 14 patients relapsed, and one died of lung cancer. Interobserver variation was significantly greater for ⁶⁷Ga than for ¹⁸FDG PET. Some 64% of patients who had a negative early restaging ¹⁸FDG PET remained free from progression versus 50% of patients with negative ⁶⁷Ga scans. Only 25% of patients with a positive PET remained disease free versus 42% of ⁶⁷Ga‐positive patients. Time to progression was associated with ¹⁸FDG PET results, but not with those by ⁶⁷Ga. ¹⁸FDG PET had better test characteristics than ⁶⁷Ga for the evaluation of early response in aggressive non‐Hodgkin's lymphoma patients.