Evaluating Prognostic Value of Patients with Newly Diagnosed Multiple Myeloma By Serum Free Light Chain κ/λ Ratio in Combination with LDH
Authors: Fu Chengcheng , Wang Panfeng , Gong Feiran , Zhou Jiazi , Yao Ying , Xu Yun , Xu Yang , Chang Huirong , Wu Depei 
Published: October 2019

Abstract
Objective The data were analyzed for the roles of the measurement of serum free light chain (sFLC) and LDH in the prognosis of newly diagnosed multiple myeloma(NDMM) patients.
Methods The clinical data was retrospectively analyzed for 96 newly diagnosed multiple myeloma(NDMM) patients at hematology department of the first affiliated hospital of Soochow's University from September 28,2012 to December 30,2105. The levels of serum free light chain and LDH were measured and the κ/λ ratios were calculated, so we could analyze the roles of sFLC and LDH in the prognosis of newly diagnosed multiple myeloma (NDMM) patients.
Results Among the patients withλlight-chain MM, theλlight-chain levels showed a significant positive correlation with serum creatinine, β2-mg and numbers of bone marrow plasma cells and it was negatively associated with levels of serum total protein. At the same time, the patients with k light-chain MM, the k light-chain levels was not showed statistically correlation with those levels above. The morbidity of renal insufficiency in theλlight-chain MM groups was 25.5%(13/51), it was 6.7%(3/45) in the k light-chain MM groups. The morbidity of renal insufficiency was more higher in theλlight-chain MM groups(P=0.009). The follow-up duration ranged from 5.0~59.3 months (mean 19 months). The median progression-free survival (PFS) was 15.1 months for the high free light chain ratio group(sFLCR≥100 or ≤0.01) and 29.1 months for the low free light chain ratio group (0.01) sFLCR<100<, respectively. And the difference was statistically significant (P<0.001).The mean of overall survival(OS) between the high free light chain ratio group and the low free light chain ratio group was 45.9 monthes and 47.5 monthes, respectively. And the difference was statistically significant (P=0.0047). Log-rank univariate analysis showed that elevated LDH levels and obvious abnormally sFLCR were independent prognostic factors of MM patients. Cox multi-factor analysis discovered that the LDH levels was the only poor-prognosis factor. The sFLCR (≥100 or ≤0.01) and LDH≧225U/L could serve as two risk factors. The patients who had one or more risk factor had poor prognosis than the patients who had none of them. The median progression-free survival(PFS) between the two groups were 15.1 months versus 29.1 months,respectively(P=0.001).The mean of overall survival(OS) between the two groups were 44.5 months versus 49.4 months, respectively(P=0.01). And the difference was statistically significant.
Conclusions The λ light-chain can more easily lead to the renal insufficiency than the k light-chain. The patients with λ light-chain MM have higher morbidity of renal insufficiency than the patients with k light-chain MM. The baseline LDH levels is the poor-prognosis factor for MM patients. We recommend combine the serum free light chain ratio with the LDH levels to evaluate the prognosis of MM patients. The patients who have either the sFLCR (≥100 or ≤0.01) or LDH≧225U/L at the time of diagnosis have poor prognosis than the patients who have none of them.

Disclosures
No relevant conflicts of interest to declare.