PET/CT as a predictor of progression-free survival in diffuse large B-cell lymphoma: a pilot study

This pilot study investigates the value of baseline total lesion glycolysis (TLG) in 18F-FDG PET/CT scans for prediction of progression-free survival (PFS) in patients with Diffuse Large B-Cell Lymphoma (DLBCL). We also evaluate the role of other quantitative parameters measured at baseline and interim PET/CT for prediction of PFS. A retrospective review (2003-2010) of patients with DLBCL who underwent 18F-FDG PET/CT before, after cycle two, and after completion of R-CHOP treatment, identified 84 patients. Twenty patients fulfilled the inclusion criteria. Standardized uptake values (SUVmax and SUVmean), total metabolic tumor volume (TMTV), and TLG were measured in baseline and interim PET/CT. Relationship between quantitative parameters and PFS was statistically analyzed using Log-rank test and univariate Cox-regression analysis. Of 20 patients (F/M: 7/13, range: 20-73 years), six patients (30%) developed recurrence after chemotherapy (mean follow-up: 51.35±17.05 months, range: 12-81 months). Results of statistical analysis showed TLG as the only discriminator of recurrence at baseline (cut-point: 704.77 g, HR: 11.21, CI: 1.29-97, P=0.02). Among the interim PET/CT parameters, SUVmean (cut -point: 2.07, HR: 6.31, CI: 1.25-31.61), SUVmax (cut-point: 2.3, HR: 6.31, CI: 1.25-31.61), and TLG (cut-point: 96.5 g, HR: 6.38, CI: 1.29 31.61) could all help predict PFS (P<0.05). Although not routinely reported, high baseline TLG may be a useful index to identify patients with DLBCL who are at increased risk for relapse after conventional R-CHOP. If confirmed in larger prospective studies, this may allow the selection of alternate therapeutic choices at the onset of treatment.