Prognostic analysis on ¹⁸F-FDG PET/CT and MYC gene in early chemotherapy with diffuse large B-cell lymphoma

Objectives: To evaluate the prognostic value on ¹⁸F-FDG PET/CT imaging and MYC gene in the early chemotherapy with DLBCL, and analyze the relationship between the SUVmax decrease proportion (ΔSUVmax%) and MYC gene.

Methods: 60 patients (29 males, 31 females, average age 50.95±2.35 (12-81) years) with pathologically confirmed DLBCL were analyzed from September 2010 to February 2016. ¹⁸F-FDG PET/CT were performed before and after 1-2 courses of chemotherapy (30 patients respectively). The ROI was drawn and the ΔSUVmax% was calculated. Patients were evaluated by the observes using Deauville 5-PS. Fluorescence in situ hybridization (FISH) was employed to detect MYC gene. Multiple liner regression, the optimum cutoff value of ΔSUVmax% by ROC curve and Kaplan-Meier analysis were used to analyze the data.

Results: There were 15 patients (25%, 15/60) with progressed disease within the follow-up, including 2 patients of stageII(10%, 2/20), 1 patient of stageIII(20%,1/5) and 12 patients of stageIV(40%, 12/30) in clinical staging or 2 patients of low middle risk group (14.29%, 2/14), 5 patients of high middle risk group (31.25%, 5/16) and 6 patients of high risk group (66.67%, 6/9) with international prognostic index (IPI). The optimum cutoff value of the ΔSUVmax% was 62.5% and scores 3 of Deauville 5-PS was used. The patients with ΔSUVmax% <62.5%, n=21, Deauville 5-PS<3, n=13 or MYC (-), n=42 showed better and longer progression-free survival (PFS) (X²=33.674, 4.083, 61.694, all P<0.05). The ΔSUVmax% was negatively correlated with MYC gene (P<0.001). No significant difference was showed in ΔSUVmax% between 1 course and 2 courses of chemotherapy (0.66±0.40 vs 0.65±0.25, P>0.05).

Conclusion: ¹⁸F-FDG PET/CT imaging in the early phase of chemotherapy and MYC gene has a better value for predicting the prognosis of DLBCL, and we therefore recommend ¹⁸F-FDG PET/CT imaging be performed after 1 course of chemotherapy.