The role of FDG-PET imaging and involved field radiotherapy in relapsed or refractory diffuse large B-cell lymphoma

We examined the role of fluorodeoxyglucose-positron emission tomography (FDG-PET) and the addition of involved field radiotherapy (IFRT) as potential modifiers of salvage therapy. From January 2000 to June 2007, 83 patients with chemosensitive relapsed or primary refractory diffuse large B-cell lymphoma (DLBCL) underwent FDG-PET scans following second-line chemotherapy before high-dose therapy with autologous stem cell rescue (HDT/ASCR). We evaluated the prognostic value of having a negative FDG-PET scan before HDT/ASCR and whether IFRT improved the outcomes. Median follow-up was 45 months, and the 3-year PFS, disease-specific survival (DSS) and OS were 72, 80 and 78%, respectively. Multivariate analysis revealed that a positive FDG-PET scan had worse PFS (hazard ratio = (HR) 3.4; P = 0.014), DSS (HR = 7.7; P = 0.001) and OS (HR = 5.4; P = 0.001), and that patients not receiving IFRT had worse PFS (HR = 2.7; P = 0.03) and DSS (HR = 2.8, P = 0.059). Patients who received IFRT had better local control with fewer relapses within prior involved sites compared with those that did not receive IFRT (P = 0.006). These outcomes confirm the important prognostic value of FDG-PET scans before undergoing HDT/ASCR. It also suggests that the role of IFRT should be evaluated further.