Prognostic impact of 18F-fluoro-deoxyglucose positron emission tomography in untreated mantle cell lymphoma: a retrospective study from the GOELAMS group

F-18-fluorodeoxyglucose (FDG) PET is a non-invasive imaging technique recommended for the management of both diffuse large B-cell and Hodgkin's lymphomas. This retrospective study investigated the value of FDG PET for initial staging and its prognostic impact on patients with mantle cell lymphoma (MCL). A total of 44 untreated MCL patients assessed by both conventional evaluations (CE) and FDG PET for initial staging were included. The maximum standardized uptake value (SUVmax) in the most intense pathological area was recorded for each patient. Disease status after chemotherapy completion was assessed according to the International Workshop Criteria (IWC) for non-Hodgkin's lymphoma (NHL) response and IWC+PET. FDG PET uptakes at diagnosis were abnormal in all cases. Compared to CT scan, nodal and extranodal sites were only detected by FDG PET. Due to insufficient sensibility for bone marrow (BM) and gastrointestinal (GI) involvement, FDG PET did not modify initial staging. Positive and negative predictive values of IWC+PET for relapse at 1 year were 62.5 and 100%. With a median follow-up of 21 months, only the International Prognostic Index (IPI) and IWC+PET modified both event-free survival (EFS) (p = .02 and .0001, respectively) and overall survival (p = .03 and .05, respectively) duration. When combining IPI and SUVmax at diagnosis, we were able to identify patients with low (29%; no relapse/progression), intermediate (42%; median EFS: 37 months) and high risk (29%, median EFS: 22 months) (p = .004). In MCL, FDG PET at diagnosis is complementary to CE, but BM and GI biopsies remain mandatory. IWC+PET criteria are highly efficient to identify patients with high risk for early relapse. Combining IPI and SUVmax may predict patient outcome and warrant further prospective investigations towards designing risk-adapted strategies.