Metabolic parameters measured on F-18 FDG PET/CT for the prediction of post-relapse survival in patients with relapsed diffuse large B-cell lymphoma

Objectives The aim of this study was to compare prognostic significance of metabolic parameters measured on F-18 FDG PET/CT before starting R-CHOP chemotherapy (initial PET) and before second-line treatment (relapse PET) for the prediction of post-relapse survival (PRS) in patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL).

Methods Twenty relapsed or refractory DLBCL patients (16 relapsed, 4 refractory) were retrospectively included. Metabolic parameters, including maximum standardized uptake value (SUVmax), whole body metabolic tumor volume (WBMTV), and whole body total lesion glycolysis (WBTLG) were measured on initial and relapse PET for each patient. PRS was calculated from the date of diagnosis of relapsed or refractory disease to the date of the death or last follow-up. Univariate and multivariate analyses for PRS were performed using the IPI score and metabolic parameters.

Results During the follow-up period (median 29 months), 13 among 20 patients died from the disease and the median value of PRS was 11 months. ROC curve analysis showed cut-off values for SUVmax, WBMTV, and WBTLG measured on relapse PET were 18.0, 53.2cm³, and 446 respectively. Univariate analysis showed that the IPI score (log-rank test, p=0.003), WBMTV (>53.2cm³; HR=5.28; p=0.001) and WBTLG (>446; HR=3.97; p=0.006) measured on relapse PET were significant predictors of PRS, but SUVmax, WBMTV, and WBTLG measured on initial PET were not significant predictors for PRS. Following multivariate analysis, WBMTV (>53.2cm³; HR=6.30; p=0.003) and WBTLG (>446; HR=4.13; p=0.013) measured on relapse PET were independent prognostic factors for PRS in patients with relapsed or refractory DLBCL.

Conclusions Our results suggest that metabolic parameters measured on relapse PET have better predictive values than these parameters measured on initial PET, and the use of these parameters together with the IPI score may be useful for detailed prediction of prognosis after relapse in DLBCL patients.