PB2169 18F‐FDG PET/CT IN PATIENTS WITH MULTIPLE MYELOMA AFTER STEM CELLS TRANSPLANTATION

Abstract

Background:Multiple myeloma is a disease of the blood system, belonging to the group of paraproteinoblastosis, characterized by proliferation of monoclonal plasma cells in the bone marrow, secreting immunoglobulins that interfere with the normal functioning of the bone marrow, causing destruction of surrounding bone structures. The incidence of multiple myeloma in the Russian Federation is 4.5 cases per 100,000 population per year, accounting for 13‐15% of cases of hemoblastosis.Aims:The aim of the study was to determine the dynamics of the activity and the prevalence of the tumor process in patients with multiple myeloma according to PET/CT with 18F‐FDG, as well as the evaluation of the effect of various characteristics of the tumor process on the accumulation level 18 F ‐ FDG.MethodsThe data of 104 PET/CT with 18F‐FDG, carried out before and after the stem cells transplantation after 25‐34 months, were analyzed. The study included 26 people (16 men and 10 women) aged 33 to 70 years (mean age 51.5 years) with an immunohistochemically confirmed diagnosis established between 2014 and 2016, and treatment in the amount of high‐dose therapy with stem cell transplantation. Patient age, disease status, process characteristics (location, nature of the lesion determined before and after transplantation, type of light chain secretion, stage Durie‐Salmon) were assessed. The relationship between the nature of the lesion and the time interval elapsed after autoTGX was determined. The influence of various characteristics of the process on the nature of the lesion and the degree of accumulation of FDG was evaluated.Results:Before transplantation in a sample of patients (n = 26) in 6 patients (23.3%) a mixed lesion was detected ‐ diffuse bone marrow lesion, extraosseous foci and localized osteolysis foci; 12 patients (46%) with localized osteolytic foci; 8 (30.7%) patients showed no specific lesion. After transplantation, localized osteolysis foci are detected in 4 (15.3%); 18 (69.3%) patients had mixed lesions; and in 4 patients (15.3%), no specific pathological changes were detected. Next, patients (n = 26) were conditionally divided among themselves into several categories according to the criteria: 1) the disease status determined before transplantation ‐ the complete response (n = 13), the partial response (n = 13); 2) the type of secretion of light chains ‐ Gk (n = 11) and Gλ (n = 15); 3) Durie‐Salmon stage ‐ with 1st and 2nd stage (n = 11), with 3rd stage (n = 15).Summary/Conclusion:The mixed lesion prevails compared with localized osteolytic foci (p <0.05). There is a statistically significant increase in the metabolic activity of the disease (p <0.05) as an increase in FDG accumulation in patients with mixed lesions (n = 18) compared with patients with localized osteolytic lesions (n = 4); as well as in patients with stage 3 Durie‐Salmon (n = 15) compared with stage 1 and stage 2 (n = 11). There were no statistically significant differences in the categories of patients with a full response and partial response, as well as in the categories of patients with the secretion of light chains Gk and Gλ. The results indicate the feasibility of using PET/CT c18F‐FDG when assessing structural changes and the effectiveness of treatment of patients with MM. Based on the results obtained, it was concluded that the maximum absorption of 18F‐FDG depends on the stage of Durie‐Salmon; on the nature of the defeat of the lesion and does not depend on the type of secretion of light chains and on the status of the disease.