Prognostic value of negative interim 2-[¹8F]-fluoro-2-deoxy-d-glucose PET/CT in diffuse large B-cell lymphoma.

AIM: To assess the prognostic value of negative interim combined 2-[(18)F]-fluoro-2-deoxy-d-glucose ((18)F-FDG) positron-emission tomography/computed tomography (PET/CT) in patients with diffuse large B-cell lymphoma (DLBCL). MATERIALS AND METHODS: Ninety-two patients with histologically proven DLBCL were enrolled. All of the patients underwent (18)F-FDG PET/CT at diagnosis, and interim PET/CT after the second cycle of chemotherapy with rituximab, cyclophosphamide, hydroxydaunorubicin, vincristine, and prednisolone (R-CHOP). Negative interim PET/CT was defined as the disappearance of all abnormal (18)F-FDG uptake compared to the pretreatment PET/CT image, as determined by visual assessment. The clinical outcome of patients was estimated as progression-free survival (PFS), and the prognostic significance of clinicopathological and imaging parameters were assessed using the Cox proportional hazards model. RESULTS: Thirty-six patients (39.1%) showed lymphoma progression within a median follow-up of 30.8 months. According to univariate analysis, Ann Arbor stage, serum lactate dehydrogenase level, Eastern Cooperative Oncology Group scale, International Prognostic Index (IPI) score, and maximum standardised uptake values on initial PET/CT were significant prognostic factors for PFS (all p<0.05). Among these parameters, only the IPI score was an independent predictor for PFS (p=0.044). Survival of patients with a high IPI score (≥3) was poorer than those with a low IPI score (0-2; p<0.001). CONCLUSION: Despite a negative interim (18)F-FDG PET/CT, approximately 39% of DLBCL patients showed progression during follow-up. Although the negative PET/CT was obtained during chemotherapy, it is important to closely follow-up patients, especially those with a high IPI score.