Midtreatment 18F-fluorodeoxyglucose positron-emission tomography in aggressive non-Hodgkin lymphoma.

BACKGROUND: The use of (18) F-fluorodeoxyglucose positron-emission tomography (PET) scan has increased considerably in the clinical management of non-Hodgkin lymphoma patients, and its role as a prognostic factor during chemotherapy has been established recently. METHODS: Between May 2003 and May 2009, 91 newly diagnosed patients with primary mediastinal large B-cell lymphoma (PMLBCL) and diffuse large B-cell lymphoma (DLBCL) were treated with 12 weekly cycles of rituximab-MACOP-B (n = 12 patients with PMLBCL), 6 cycles of rituximab-CHOP21 (n = 65 patients with DLBCL, aged < 60 years and 1 patient with PMLBCL), or 8 weekly cycles of rituximab-VNCOP-B (n = 13 DLBCL patients, aged ≥ 60 years). All patients underwent a staging PET examination at baseline and a midtreatment (interim) PET examination after 6 weeks of rituximab-MACOP-B treatment, 3 cycles of rituximab-CHOP21 treatment, or 4 weeks of rituximab-VNCOP-B treatment and again at the end of the chemo-immunotherapy regimen. RESULTS: At midtreatment evaluation, 35 patients showed a persistently positive PET scan; only 6 (17%) of these patients achieved a continuous complete response (CCR). However, 56 patients presented with a negative interim PET, and 50 (89%) of these patients achieved and maintained a CCR. Comparison between the 2 PET groups indicated a statistically significant association between PET findings and event-free survival (P = .0001) and overall survival (P = .0001). CONCLUSIONS: The results of this study indicated that midtreatment PET may represent a significant step forward in helping physicians make crucial decisions on further treatment.