Prognostic value of positron emission tomography/computed tomography metabolic parameters in assessing primary gastrointestinal diffuse large B-cell lymphoma.

[PURPOSE] This study aimed to evaluate the prognostic significance of fluorine-18 (18F) fluorodeoxyglucose PET/computed tomography (CT) metabolic parameters in patients with primary gastrointestinal diffuse large B-cell lymphoma (PGI-DLBCL).

[METHODS] We retrospectively analyzed 24 PGI-DLBCL patients treated with R-CHOP chemotherapy. Continuous variables were dichotomized at the median and compared using the t-test, whereas categorical variables [e.g. gender, cell origin (germinal center B-cell/non-germinal center B-cell)] were compared using the Chi-square test. Spearman correlation analysis was performed to examine relationships between metabolic parameters and potential prognostic factors. Univariate Kaplan-Meier survival analysis and multivariate Cox regression were used to identify independent prognostic factors for progression-free survival and overall survival. Prognostic differences among risk groups were also assessed.

[RESULTS] Total lesion glycolysis (TLG), lactate dehydrogenase, International Prognostic Index (IPI), National Comprehensive Cancer Network-IPI, metabolic tumor volume (△MTV, representing changes in MTV between baseline and interim PET/CT), and clinical staging differed significantly between high and low-MTV groups (all P < 0.05).TLG, △MTV, lactate dehydrogenase, IPI score, National Comprehensive Cancer Network-IPI score, and clinical stage were significantly correlated with MTV (all P < 0.05). Receiver operating characteristic analysis indicated that MTV, standardized uptake value (△SUVmax, changes in SUVmax between baseline and interim PET/CT), TLG, and ΔMTV effectively predicted mid-term remission. Multivariate analysis identified MTV and ΔSUVmax as independent predictors of progression-free survival (P < 0.05), whereas ΔSUVmax was independently associated with overall survival (P < 0.05). Cox regression analysis revealed significant prognostic differences among subgroups (P < 0.0001).

[CONCLUSION] MTV, △SUVmax, TLG, and △MTV are effective for evaluating for mid-term remission in PGI-DLBCL patients. Among them, MTV and △SUVmax serve as independent prognostic factors.