The role of PET in the treatment of b-cell lymphoproliferative disorders in a real-world clinical setting in Russia

Objective. Assessment of the role of positron emission tomography (PET) in the diagnosis and treatment of B-cell lymphoproliferative disorders (B-LPD) in Russian real-world clinical practice from 2014 to 2017. Materials and Methods. The EQUILIBRIUM, a post marketing multicenter study, included 1000 patients aged 21 to 91 years with a verified diagnosis of B-cell non-Hodgkin»s lymphoma (B-NHL) or chronic lymphocytic leukemia (CLL) who received at least 4 cycles of rituximab-containing therapy with Acellbia®. The main method for the assessment of the disease dissemination, the size and location of the lesions was computed tomography, which was used in 76.2 % of patients. PET was performed in 324 (32.4 %) patients: in 152 (47 %) cases during initial diagnosis, PET during treatment in 102 (31 %) patients and - in the vast majority, i. e. 310 (96 %) patients - after completion of induction chemo-immunotherapy. Results. According to the results of interim PET, complete remission was achieved in 44 (43 %) of 102 patients, partial remission - in 53 (52 %) cases, stabilization of the disease was observed in 5 (5 %) patients, and no cases of progression among patients who underwent interim PET was detected. The main evidence of the final PET assessment efficacy was the achievement of complete remission (CR) in 235 (75.8 %) cases; partial remission (PR) was observed in only 61 (19.7 %) patients, and disease progression was reported in 14 (4.5 %) of cases. The median follow-up was 15 months (range from 1 to 42 months). As expected, the median overall survival (OS) as well as the median event-free survival (EFS) has not been reached for this period of time. There was a statistically significant effect of the results of interim PET on event-free survival (p = 0.07661) without a significant effect on overall survival (p = 0.69868). The depth of response recorded during the final PET scan turned out to be a prognostically significant factor for both EFS and OS (p = 0.00000). Conclusion. Positron emission tomography is a modern and effective method for diagnosing and assessing the efficacy of therapy in B-cell lymphoproliferative disorders, which is used for only 1 / 3 of patients in a real-world clinical practice. Nevertheless, the role of this method in assessing the effectiveness of therapy is beyond doubt.