[The roles of serum free light chain ratio in the diagnosis and prognosis of newly diagnosed multiple myeloma].

objectiveThe roles of serum free light chain ratio (sFLCR) in the diagnosis and prognosis of newly diagnosed multiple myeloma (NDMM) patients were analyzed.

methodsThe clinical data was retrospectively analyzed for 82 newly diagnosed multiple myeloma (NDMM) patients in the first affiliated hospital of Soochow University from September 28, 2012 to July 18, 2105. The serum free light chain levels were measured and κ/λ ratios were calculated, so we could analyze the roles of sFLCR in the diagnosis and prognosis of newly diagnosed multiple myeloma (NDMM) patients.

resultsIt was 85.5% (70/82) positive of M protein by serum protein electrophoresis (SFE) and 93.9%(77/82) by serum immunofixation electrophoresis (IFE). Both sFLC and sFLCR abnormalities were 96.3% (79/82). The estimated 40-months overall survival was 87% for the high free light chain ratio group (sFLCR ≥100 or≤0.01) and 61% for the low free light chain ratio group (0.01<sFLCR<100), respectively, with a statistical significance (P=0.034). Compared with low sFLCR group, high sFLCR group had elevated levels of serum creatinine, bone marrow plasma cells and β2-MG; lower level of hemoglobin; higher proportion of patients with renal dysfunction and selecting hemodialysis; more patients with DS stage ⅢB and ISS stage Ⅲ; higher proportion of abnormal fluorescence in situ hybridization (FISH) and λ chain isotype. The low risk group had a rise of κ chain isotype (all P<0.05). And the difference was not statistically significant when compared with the age, sex, TP, ALB, CRP, LDH, Ca(2+), M protein and chromosome. After 3-4 courses of induction chemotherapy, based on the response criteria formulated by the IMWG for patients who could reach the Very Good Remission or better (VGPR+), the responses of VGPR+ were 45.2% (19/42) in high sFLCR group and 72.5% (29/40) in low group (P=0.012). Among them, there were 14 cases (17.1%) of NDMM with renal dysfunction. The 2-year survivals in patients with renal insufficiency and normal renal function were 85.7% and 91.2% (P=0.894), respectively.

conclusionsFLC assay is much more sensitive than the common methods used, such as SPE and IFE for the diagnosis of MM. The patients with significantly abnormal sFLCR have more tumor burden, higher aggressive progression, and adverse prognosis. Compared with the patients who have normal renal function, the patients with renal insufficiency acquire the same effect after receiving reasonable treatment actively.