Immunoglobulin free light chains and solitary plasmacytoma of bone.
An abnormal serum immunoglobulin free light chain (FLC) ratio at diagnosis may identify risk of progression to myeloma in patients with solitary bone plasmacytoma (SBP). In the cohort of 116 patients, 43 have progressed to myeloma, with a median time to progression of 1.8 years. The FLC ratio was determined in all 116 patients on serum collected at time of diagnosis and was abnormal in 54 patients (47%). An abnormal FLC ratio was associated with a higher risk of progression to myeloma (P = .039). The risk of progression at 5 years was 44% in patients with an abnormal serum FLC ratio at diagnosis compared with 26% in those with a normal FLC ratio. One to 2 years following diagnosis, a persistent serum M protein level of 5 g/L (0.5 g/dL) or higher was an additional risk factor for progression. A risk stratification model was constructed using the 2 variables of FLC ratio and M protein level: patients with a normal FLC ratio at baseline and M protein level less than 5 g/L (0.5 g/dL) at 1 to 2 years following diagnosis (low risk, n = 31); with either risk factor abnormal (intermediate risk, n = 26); and with both an abnormal FLC ratio and M protein level of 5 g/L (0.5 g/dL) or higher (high risk, n = 18). The corresponding progression rates at 5 years were significantly different in the low, intermediate, and high groups: 13%, 26%, and 62%, respectively (P < .001).
Dingli
David
D
Division of Hematology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
Kyle
Robert A
RA
Rajkumar
S Vincent
SV
Nowakowski
Grzegorz S
GS
Larson
Dirk R
DR
Bida
John P
JP
Gertz
Morie A
MA
Therneau
Terry M
TM
Melton
L Joseph
LJ
Dispenzieri
Angela
A
Katzmann
Jerry A
JA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000175:diagnosis / Q000209:etiology / Q000276:immunology*; D005260:Female; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000209:etiology / Q000276:immunology; D015999:Multivariate Analysis; D009194:Myeloma Proteins / Q000378:metabolism; D010954:Plasmacytoma / Q000175:diagnosis / Q000276:immunology*; D012307:Risk Factors; D013997:Time Factors
D007147:Immunoglobulin Light Chains; D009194:Myeloma Proteins