PB1837 THE PREDICTIVE VALUE OF PET/CT SCAN IN DIFFUSE LARGE B‐CELL LYMPHOMA IN OPTIMIZING THE TREATMENT DECISION

Abstract

Please indicate where the abstract has been published before: Cancer Biology journal December 2018.Background:Diffuse large B cell lymphoma (DLBCL) is the main histologically subtype of aggressive non‐Hodgkin lymphomas (NHL). The role of 18F‐FDG PET/CT scan in DLBCL is well established at the baseline and at the end of therapy. Many studies reported that patients with a negative scan after initial 2‐3 cycles of chemotherapy demonstrated both an improvement in overall survival (OS) and in progression free survival (PFS). Therefore it is important to determine an accurate predictive tool to stratify patients who are more likely to relapse, to allow clinicians to modify their treatment accordingly.Aims:We aimed at evaluation the prognostic importance of the interim 18F‐FDG PET/CT in patients (pt) with pathologically proven DLBCL to modify the treatment accordingly.Methods:This prospective study was a co‐operative work between nuclear medicine unit and clinical oncology unit in Kasr El Ainy Center of Clinical Oncology and nuclear medicine after being approved by the ethical committee. This study included thirty‐nine patients,with newly diagnosed pathologically proven DLBCL presented to us between June 2015 and July 2017.Pts were subjected to whole body 18F‐FDGPET/CT as a baseline and after 3 cycles of chemotherapy (interim PET). According to interim PET results the pts were subdivided into 2 categories; the 1st category is metabolic responders (PET‐negative pts) including pts with complete and partial response (PR). The 2nd category is metabolic non‐responders (PET‐positive pts) with progressive and stable disease according to Deauville criteria (5‐point scale), and interpretation of the results was done using EORTEC and RECIST scale (European Organization for Research and treatment of cancer; RECIST, Response Evaluation Criteria in Solid Tumors). PET negative pts completed their pre planned treatment protocols, whereas PET‐positive pts group received 2nd line chemotherapy.At the end of treatment (6 cycles of chemotherapy), further follow‐up was done by PET‐CT scan (PET‐E). Metabolic response assessment was done by using Deauville criteria and also interpretation of the results was done using EORTC and RECIST scales.Results:Between June 2015 and July 2017, the study included 39 pts. Thirty‐one pts received R‐CHOP‐21 and 8 pts received R‐EPOCH‐21. All pts were subjected for a complete assessment with interim PET‐I scan (PET‐I), a baseline scan and an end‐of‐treatment scan (PET‐E). According to PET‐I (interim PET) results, pts were subdivided into metabolic responders (PET‐negative pts) including pts with complete and partial response and metabolic non‐responders (PET‐positive pts) with progressive and stable disease using Deauville criteria. PET‐negative pts 92.3% (36 pts) received three additional courses,where as in PET‐positive pts (3 pts) 2nd line chemotherapy was prescribed (two pts received GEMOX and the other one received ESHAP). Two of them were still non‐responder at the end‐of‐treatment study while the other one became responder. PET/CT scan post therapy: 89.7% of pts (n = 35) were metabolic responders and 10.3% (n = 4) were metabolic non‐responders. Two pts of the end treatment non‐responders were also non responder at the interim study while the other two pts were responders at the interim study.Summary/Conclusion:Optimizating the treatment decision in pts with DLBCL is of great importance as conventional chemotherapy has been shown to be effective only in 60% of pts. Using PET‐CT is of value in optimizing the treatment decision and early shift of first line of chemotherapy for non‐responding pts.image