Prognostic Role Of Monoclonal and Polyclonal Gammopathy Measured By Serum Free Light Chain and Immunofixation In Diffuse Large B-Cell Lymphoma

Background Serum free light chain (FLC) assay has been used to evaluate the prognosis of several hematologic malignancies. We evaluated the prognostic role of monoclonal gammopathy (MG) and polyclonal gammopathy (PG) measured by serum FLC and immunofixation (IF) in DLBCL. Patients and methods We retrospectively reviewed 115 patients with DLBCL who treated with rituximab containing chemotherapy. MG was defined as elevated kappa (κ) or lambda (λ) FLC with abnormal κ to λ ratio or positive IF and PG was defined as elevated κ and/or λ FLC with normal κ to λ ratio and negative IF. Results Fifty-six (48.7%) patients had an elevated FLC. Twenty (17.4%) patients had MG and 39 (33.9%) patients accompanied by a PG. Two-year overall survival (OS) was 89.2%, and 2-year event-free survival (EFS) was 88.4%. Elevated FLC was associated with inferior OS and EFS ( p= 0.013 , p =0.012). Patients with MG had an inferior OS and EFS compared to patients with normal FLC ( p= 0.006 , p =0.011). In multivariate analysis, both elevated FLC and MG showed the significance for OS (HR 4.57, 95% CI 1.43-14.60, p =0.001 and HR 5.63, 95% CI 1.50-21.09, p =0.010). Elevated FLC did not show the significantly shorter OS or EFS in non-germinal center B-cell (GCB) type according to the Han’s criteria. However, MG was a significant prognostic factor for OS and EFS in non-GCB type (HR 6.28, 95% CI 1.21-32.62, p =0.029, HR 6.38, 95% CI 1.58-25.74, p =0.009). Conclusion It important to evaluate the associated MG and PG using serum FLC and IF for predicting the prognosis of DLBCL, especially in non-GCB subtype. Disclosures: No relevant conflicts of interest to declare.