Serum Free Light Chain Assay as a Prognostic Marker in Patients with Aggressive B-Cell Non-Hodgkin's Lymphoma: Impact on Survival Outcome

Background The role of serum free light chain (FLC) as a prognostic biomarker in lymphoproliferative diseases is being increasingly studied. In this study we present the 5-year survival outcome for patients with aggressive B-cell non-Hodgkin's lymphoma (NHL) and their relation to FLC and other known prognostic markers. Materials and Methods This is a prospective study conducted in patients diagnosed with aggressive B-cell NHL. Serum FLC level and ratio were estimated prior to initiation of treatment. Results A total of 100 patients were included in the study from December 2013 to December 2015 with a median age of 53 years. Thirty-eight patients (38%) had elevated FLC level of which 26% were polyclonal and 12% were monoclonal elevations. Abnormal FLC ratio was noted in 12% patients. Median follow-up duration of the study was 75 months. Five-year relapse-free survival (RFS) for the study population was 54.4%. Five-year RFS was 64.1% for early stage and 48.2% for advanced stage diseases ( p = 0.05). The RFS was significantly better in age less than 60 years (59.5% vs 43.8%, p < 0.001). Five-year overall survival (OS) was 61.3%. OS was significantly better in younger patients (73.6% vs 33.4%, p < 0.001), with International Prognosis Index score of 0 to 2 (87.4% vs 26.7%, p < 0.001). Patients with elevated FLC had inferior RFS (50% vs 71.4%, p = 0.04). Abnormal FLC ratio also strongly corresponded to inferior RFS (54.5% vs 66.2%, p = 0.001). OS was also significantly inferior in patients with abnormal FLC ratio (72.6% vs 63.6%, p = 0.001). Conclusion In patients with newly diagnosed aggressive B-cell NHL, elevated FLC levels and abnormal FLC ratio were significantly associated with inferior survival.