Prognostic value of interim and end-of-treatment ¹⁸F-FDG PET/CT in patients with diffuse large B-cell lymphoma

Objective: To compare the value of interim and end-of-treatment ¹⁸F-fluorodeoxyglucose (FDG) PET/CT for the prognosis of patients with diffuse large B-cell lymphoma (DLBCL). Methods: A total of 116 DLBCL patients (male: female = 1: 1.32, average age: (57.87 ± 15.89) years) whose initial treatment was rituximab + cyclophosphamide + doxorubicin + vincristine + prednisone (R-CHOP), were enrolled from 2008 to 2016. All patients underwent pre-treatment, interim and end-of-treatment ¹⁸F-FDG PET/CT. End points were progression-free survival (PFS) and overall survival (OS). Correlation between metabolic parameters including maximum standardized uptake value (SUV_max), metabolic tumor volume (MTV), total lesion glycolysis (TLG), Deauville score (DS), ΔSUV_max, ΔMTV, ΔTLG in the interim PET/CT and those in the end-of-treatment PET/CT was analyzed with Pearson correlation analysis. The ability of metabolic parameters to assess the prognosis was evaluated by receiver operating characteristic (ROC) curve analysis. The survival was analyzed by Kaplan-Meier method and hazard ratio (HR) was calculated by Cox regression model. Results: The r values for ΔSUV_max, ΔMTV, ΔTLG of interim and end-of-treatment PET/CT were 0.630, 0.912, 0.955, respectively (all P < 0.01). One hundred and four cases (89.7%, 104/116) had the same DS in the interim and end-of-treatment PET/CT, and the r value for DS between two PET/CT scans was 0.733 (P < 0.01). The interim metabolic parameters were superior to that at the end of treatment in evaluating the progression. The 5-year PFS (83.1% vs 35.9%, P < 0.01; HR = 5.969, P < 0.01) and OS (95.7% vs 75.5%, P < 0.01; HR = 8.161, P < 0.05) rates were significantly higher in DS 1-3 group than those in DS 4-5 group. Conclusions: Interim PET/CT is effective for the prediction of prognosis in DLBCL patients with R-CHOP treatment. Patients with complete remission in the interim can omit the end-of-treatment PET/CT. (authors)