Immunoglobulin free light chain ratio is an independent risk factor for progression of smoldering (asymptomatic) multiple myeloma.
We hypothesized that increased monoclonal free kappa or lambda immunoglobulin light chains in smoldering multiple myeloma (SMM), as detected by the serum free light chain (FLC) assay, indicates an increased risk of progression to active myeloma. Baseline serum samples obtained within 30 days of diagnosis were available in 273 patients with SMM seen from 1970 to 1995. At a median follow-up of surviving patients of 12.4 years, transformation to active disease has occurred in 59%. The best breakpoint for predicting risk of progression was an FLC ratio of 0.125 or less, or 8 or more (hazard ratio, 2.3; 95% CI, 1.6-3.2). The extent of abnormality of FLC ratio was independent of SMM risk categories defined by number of bone marrow plasma cells (BMPCs) and size of serum M proteins (BMPC>or=10% and serum M protein>or=3 g/dL; BMPC>or=10% but serum M protein<3 g/dL; and serum M protein>or=3 g/dL but BMPC<10%). Incorporating the FLC ratio into the risk model, the 5-year progression rates in high-, intermediate-, and low-risk groups were 76%, 51%, and 25%, respectively. The serum immunoglobulin FLC ratio is an important additional determinant of clinical outcome in patients with SMM.
Dispenzieri
Angela
A
Department of Internal Medicine, Mayo Clinic College of Medicine, Rochester, MN, USA.
Kyle
Robert A
RA
Katzmann
Jerry A
JA
Therneau
Terry M
TM
Larson
Dirk
D
Benson
Joanne
J
Clark
Raynell J
RJ
Melton
L Joseph
LJ
Gertz
Morie A
MA
Kumar
Shaji K
SK
Fonseca
Rafael
R
Jelinek
Diane F
DF
Rajkumar
S Vincent
SV
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001854:Bone Marrow Cells / Q000378:metabolism* / Q000473:pathology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006023:Glycoproteins / Q000097:blood*; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000097:blood* / Q000401:mortality / Q000473:pathology; D010950:Plasma Cells / Q000378:metabolism* / Q000473:pathology; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012307:Risk Factors
D006023:Glycoproteins; D007147:Immunoglobulin Light Chains; C023587:protein M (glycoprotein)