Risk stratification of diffuse large B-cell lymphoma with interim PET-CT based on different cutoff Deauville scores.

We evaluated the usefulness of interim 18F-FDG PET/CT for risk stratification using different cutoff values of the Deauville 5-point scale (5-DS) in DLBCL patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). One hundred and fifty patients underwent interim (I-) and end of treatment (EOT-) PET/CT scans. Applying the conventional 5-DS cutoff value of scores 4 to 5 at interim, there was no significant difference in progression free survival (PFS) between I-PET negative and I-PET positive patients. In comparison, PFS was inferior in patients with a score of 5 on I-PET scan compared with those with a score in between 1 to 4 (28.6% vs. 78.7%, p < .0001), and positive predictive value (71.4%) was improved compared to that obtained using cutoff value of scores 4 to 5 (34.9%). Our study shows that a cutoff score of 5 at interim has an alternative clinical implication for identifying patients at a significant risk.