Abstract:
Objective To investigate the predictive accuracies of four indicators based on the interim 18F-fluorodeoxyglucose (FDG) PET/CT in terms of their efficacy and prognoses in patients with extranodal diffuse large B-cell lymphoma (EN-DLBCL).
Methods Data of a total of seventy-seven newly diagnosed patients (35 males, 42 females; aged (62.7±16.2) years) with EN-DLBCL confirmed by histopathological examination or follow-up results were retrospectively analyzed from May 2011 to April 2020, including baseline PET/CT before treatment, interim PET/CT during initial chemotherapy for 3 to 4 cycles, and clinical data. Follow-up was performed through the hospital's electronic medical record system or phone call. Using the receiver operating characteristic (ROC) curve to select the optimal cutoff value for interim SUVmax, patients were divided into SUVmax < the cutoff value group and ≥ the cutoff group. Following the clinical practice guideline of 18F-FDG PET/CT and PET/MR in lymphoma (2021 edition), ΔSUVmax=70% was chosen as the cutoff value, patients were divided into ΔSUVmax%<70% group and ≥70% group. Based on the Deauville five-point scale, patients were divided into 1–3 group and 4–5 group. According to the Lugano classification criteria, patients were divided into the disease remission group and unrelieved group based on the interim response evaluation. The χ2 test, Kaplan-Meier, and Cox regression analysis were performed to analyze SUVmax, Deauville five-point scale, and the Lugano classification criteria based on interim PET/CT and ΔSUVmax% between baseline PET and interim PET in order to predict the efficacy of primary chemotherapy and prognosis of EN-DLBCL.
Results (1) At the end of primary chemotherapy, 51 patients (66.2%) achieved complete remission (CR). The rates of CR in SUVmax<4.9 group and Deauville scores 1–3 group were 82.6% (38/46) and 85.0% (34/40), respectively, which were significantly higher than those of the other corresponding groups (χ2=13.699, 13.108, both P<0.001). No significant difference was found between the rates of CR of patients grouped by ΔSUVmax70% or the interim response evaluation based on the Lugano classification criteria (χ2=0.018, 0.368, both P>0.05). (2) The median follow-up time was 24 (4–105) months. In addition, 19 patients (24.7%) progressed, relapsed, or died at the end of follow-up. Patients in the SUVmax<4.9 group, Deauville scores 1–3 group, or remission group assessed by the Lugano classification criteria had significantly higher 2-year progression-free survival (PFS) than those in the other corresponding groups (χ2=6.148, 4.586, and 4.765, all P<0.05). The 2-year overall survival (OS) of the remission group was significantly higher than that of the nonremission group (χ2=7.248, P=0.007). No significant difference was found in the PFS or OS between patients grouped by ΔSUVmax70% (χ2=0.051, 3.331, both P>0.05). Furthermore, multivariate COX analysis confirmed that Lugano classification criteria and International Prognosis Index were independent predictors of PFS (HR=12.179, 14.330, P=0.015, 0.005) and OS (HR=8.645, 8.903, P=0.008, 0.041) in EN-DLBCL patients.
Conclusion Among the four assessment indicators of interim PET/CT in patients with EN-DLBCL, the interim SUVmax<4.9 and the Deauville scores 1–3 were the better indicators for predicting CR at the end of primary chemotherapy, whereas the interim Lugano classification criteria can be considered an independent predictive factor of PFS and OS.
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