To evaluate prognostic significance of metabolic-derived tumour volume at staging 18-flurodeoxyglucose PET-CT scan and to compare it with standardized uptake value-based response evaluation on interim 18-flurodeoxyglucose PET-CT scan in patients of non-Hodgkin's lymphoma (diffuse large B-cell lymphoma).

Introduction: To evaluate whether metabolic tumour volume (MTV) can be used as a prognostic indicator in patients with diffuse large B-cell lymphoma (DLBCL).

Materials And Methods: Eighty-nine patients with DLBCL who underwent staging fluorodeoxyglucose PET-computed tomography (FDG PET-CT) scan were included in this study and followed up, up to a period of 5 years. Whole-body PET-CT was performed at staging and the total MTV of all FDG avid lesions was calculated for each patient at a threshold of 42% of SUVmax. Out of 89 patients studied, six patients had persistent disease after chemotherapy, 24 had recurrence during follow-up and 59 patients remained disease free. In this study, prognostic significance of the interim PET-CT scan was also analysed. Out of 89 patients, 81 underwent interim PET-CT scan. Receiver operator curve (ROC) analysis was done to determine MTV baseline cutoff along with sensitivity and specificity. For interim PET-CT scan prognostic evaluation, sensitivity and negative predictive value were calculated.

Results: Among all 89 patients, the estimated area under the ROC curve was 0.851 and the MTV cutoff was 185.63 cm with sensitivity and specificity of 86.67% and 84.75%, respectively. In subset analysis of MTV cutoff, sensitivity and specificity were calculated for both the groups. For prognostic significance of the interim PET-CT scan, sensitivity and negative predictive value of staging MTV were much more than that of the interim PET-CT.

Conclusion: Baseline MTV can be used as a prognostic marker in DLBCL patients. Chemosensitive interim PET-CT scan is not a good prognostic marker compared with MTV.