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Benson, Joanne

Mayo Clinic

Mayo Clinic in Florida

Citations 9

Sequential FIB-4–based testing limits detection of fibrotic MASLD despite optimized ELF thresholds
Bobek, Olivia J., Canning, Rachel E., Benson, Joanne, Graham, Rondell, Venkatesh, Sudhakar, Allen, Alina M. , Bobek, Olivia , Eslami, Maysa , Benson, Joanne T., Venkatesh, Sudhakar K. , Yin, Meng , Ehman, Richard L. , Ou, Fang‐Shu

Hepatology Communications | August 7, 2026 | Volume: 10 | Issue: 9 | Pages: No page available

10.1097/hc9.0000000000001012 Get It

Background: Societal guidance recommends sequential noninvasive testing for metabolic dysfunction–associated steatotic liver disease (MASLD), using Fibrosis-4 (FIB-4) ≥1.3 as a gatekeeper before second-line assessment with the Enhanced Liver Fibrosis (ELF) score (<7.7 as a rule-out). The impact of this pathway design on the detection of fibrotic MASH remains uncertain. We aimed to evaluate the performance of guideline-endorsed sequential testing and to determine optimized ELF thresholds within alternative strategies. Methods: In this prospective study, patients with or at risk for MASLD underwent FIB-4, ELF testing, magnetic resonance elastography (MRE), and liver biopsy within 1 month. Fibrotic MASLD was defined as fibrosis stage ≥2 on histology or liver stiffness ≥3.1 kPa on MRE. Diagnostic performance of ELF was assessed, and sequential (ELF applied after FIB-4 ≥1.3) and concurrent (either test positive) testing strategies were compared. Results: Among 186 participants (median age 51 years; 69% women), fibrotic MASLD was present in 71 (38%). ELF demonstrated AUROC 0.77 (95% CI 0.70–0.84); the cohort-derived cutoff was 9.4 (80% sensitivity, 65% specificity). Lower cutoffs (8.7 and 7.7) increased sensitivity (≥90% and 100%) but low specificity (34% and 4%). FIB-4 ≥1.3 showed limited sensitivity (57%), resulting in 43% of fibrotic MASH cases being excluded from second-line testing. Sequential application of ELF, therefore, failed to overcome this sensitivity ceiling. A concurrent strategy using FIB-4 ≥1.3 or ELF ≥9.4 improved sensitivity to 87% with 64% specificity. Conclusions: Sequential FIB-4–based testing substantially limits the detection of fibrotic MASLD due to gatekeeping sensitivity constraints. Concurrent first-line testing with FIB-4 and ELF improves case identification, underscoring the importance of pathway design in optimizing noninvasive fibrosis assessment.
Population perspectives on benefits and harms of screening for metabolic dysfunction–associated steatotic liver disease
Allen, Alina M. , Kim, W. Ray , Canning, Rachel, Ou, Fang‐Shu , Benson, Joanne, Olson, Jessica L. , Venkatesh, Sudhakar K. , Li, Jiahui , Yin, Meng , Eslami, Maysa , Berg, Jonathon, Lazarus, Jeffrey V. , Canning, Rachel E. , Carrieri, Patrizia , Canning, Rachel , Ou, Fang-Shu , Venkatesh, Sudhakar K , Li, Jiahui , Eslami, Maysa , Ehman, Richard , Lazarus, Jeffrey V , Allen, Alina M , Yin, Meng , Carrieri, Patrizia , Benson, Joanne T., Ehman, Richard L.

Hepatology | March 19, 2025 | Volume: 83 | Issue: 2 | Pages: 362-373

10.1097/hep.0000000000001311 Get It

Background and Aims: Screening for diseases can have psychological impacts, such as anxiety, and requires acceptability from the population to be effective. This study examined the perspectives on the benefits and harms of screening for metabolic dysfunction–associated steatotic liver disease (MASLD) among the general population to optimize screening practices. Approach and Results: A survey was sent to participants enrolled between 2020 and 2024 in a prospective MASLD screening study in Olmsted County, MN. The survey assessed participants' perceived anxiety, stigma, quality of life, preferred screening methods, financial concerns, and lifestyle impacts following screening and diagnosis. Of the 461 participants, 342 (74%) completed the survey. Overall, 14% of participants reported screening-related anxiety, and 14% were concerned about disclosing a potential MASLD diagnosis to others. Among those without a MASLD diagnosis, 99% felt reassured about their liver health, 48% reported an improved quality of life, and 25% made lifestyle changes pertaining to their diet, alcohol use, and physical activity. Of the 77 participants diagnosed with MASLD, 52% experienced some anxiety about their new diagnosis; however, 95% and 97% considered it important to receive an early MASLD diagnosis to mitigate the risk for cirrhosis and cardiovascular disease, respectively. Notably, 79% of diagnosed participants found the diagnosis beneficial in adopting healthier habits, with 30% achieving a >10% weight loss after screening. Conclusion: This population-based survey demonstrates that the perceived benefits of proactive MASLD screening, such as increased awareness, lifestyle changes, and early diagnosis, outweigh the harms. These findings highlight the importance of early screening through patient-centered protocols to improve health outcomes.
Clinical Course and Prognosis of Smoldering (Asymptomatic) Waldenstrom’s Macroglobulinemia
Kyle, Robert A. , Benson, Joanne, Therneau, Terry M. , Melton, L. Joseph, Benson, Joanne T., Larson, Dirk R. , Dispenzieri, Angela , Rajkumar, S. Vincent

Blood | April 18, 2020 | Volume: 112 | Issue: 11 | Pages: 2709-2709

10.1182/blood.v112.11.2709.2709 Get It

Abstract Smoldering Waldenström’s Macroglobulinemia (SWM) is defined as a serum IgM monoclonal protein ≥3 g/dL and/or ≥10% bone marrow lymphoplasmacytic infiltration but no evidence of constitutional symptoms, symptomatic anemia, or hyperviscosity. Forty-eight patients with SWM were identified at Mayo Clinic from 1974 to 1995. Patients with a diagnosis of chronic lymphocytic leukemia or lymphoma or history of any antineoplastic therapy before diagnosis of SWM were excluded. The median age at diagnosis was 63 years (range 39–87 years). Only one patient (2%) was &lt; 40 years of age, but 14 percent were &lt; 50 years old. Thirty-two (67%) were men, and 16 (33%) were women. At diagnosis, hepatomegaly was noted in 10%, splenomegaly in 4%, and lymphadenopathy in 8%. The initial hemoglobin level ranged from 8.7 to 15.3 g/dL (median 11.8). The anemia in all 4 patients with an initial hemoglobin &lt; 10 g/dL was due to other causes such as myelodysplastic syndrome, bronchopleural fistula, Barrett’s esophagus, and Coumadin administration. The initial leukocyte level ranged from 3.2 to 13.2 × 109/L (median 5.7), and platelets ranged from 101 to 578 × 109/L (median 285.5). Only one patient had a serum creatinine &gt; 2.0 mg/dL and it was unrelated to SWM. The serum monoclonal protein level at the time of diagnosis ranged from 1.5 to 5.2 g/dL (median 3.3); 12 (25%) were &lt; 3 g/dL, while 10 (21%) were ≥4 g/dL. IgM kappa accounted for 75%, IgM lambda 21%, and 2 (4%) were biclonal. Immunofixation of the urine was positive in 97% (kappa 80%, lambda 17%, indeterminate 3%) of those tested. The size of the urine M protein ranged from unmeasurable to 1.4 g/24h (median 0.04 g/24h). Serum albumin ranged from 2.5 to 4.3 g/dL (median 3.6). Five patients (10%) had an albumin value &lt; 3 g/dL. Ten (26%) had a reduction of 1 uninvolved immunoglobulin, while 8 (21%) had a reduction of both IgG and IgA immunoglobulins. Lymphoplasmacytic infiltration of the bone marrow ranged from 3% to 80%, (median 30%). Three (6%) had less than 10% infiltration, while 13 (27%) had 50% or greater infiltration. The 48 patients were followed for a total of 292 (range 0.5 to 22.6 years; median 3.7) person-years, during which time 33 progressed to symptomatic WM and one to AL amyloidosis. The expected number of WM based on the SEER data was 0.004 cases. Thus, relative risk of progression to WM was increased 7,586-fold (95% CI, 5,083 to 10,373). The median time to progression was 4.6 years. The absolute risk of progression to WM was 6% at 1 year, 39% at 3 years, and 55% at 5 years. The median survival after progression to symptomatic WM was 5.1 years. Seventy-three percent of patients died, indicating a robust follow-up. We evaluated sex, hemoglobin level, size of serum M protein, reduction of uninvolved immunoglobulins, presence of urinary monoclonal light chains, serum albumin level, and the proportion of lymphoplasmacytic infiltration of the bone marrow as risk factors for progression. Significant risk factors for progression with univariate analysis included size of the serum M protein, hemoglobin level, reduction in uninvolved immunoglobulins, and degree of bone marrow lymphoplasmacytic cell infiltration. Multivariate modeling revealed that the size of the M protein and the degree of bone marrow infiltration were the most important risk factors. We conclude that smoldering WM is a distinct clinical entity that needs to be differentiated from IgM MGUS and symptomatic Waldenstrom’s Macroglobulinemia.
Immunoglobulin Free Light Chain Ratio Is an Independent Risk Factor for Progression of Smoldering Multiple Myeloma.
Kyle, Robert A. , Katzmann, Jerry A., Benson, Joanne, Clark, Raynell, Melton, L. Joseph, Kumar, Shaji , Jelinek, Diane F., Dispenzieri, Angela , Larson, Dirk R. , Benson, Joanne T., Gertz, Morie A. , Fonseca, Rafaël , Rajkumar, S. Vincent

Blood | April 18, 2020 | Volume: 110 | Issue: 11 | Pages: 1487-1487

10.1182/blood.v110.11.1487.1487 Get It

Abstract Background: Smoldering multiple myeloma (SMM) is an asymptomatic plasma cell proliferative disorder with a high risk of progression to symptomatic multiple myeloma. Identification of risk factors that predict progression of SMM to symptomatic MM could identify higher risk patients who might benefit from chemoprevention or more intensive surveillance. We hypothesized that increased monoclonal free kappa or lambda immunoglobulin light chains in smoldering myeloma (SMM), as detected by the serum free light chain (FLC) assay, indicates an increased the risk of progression to active myeloma. Methods: Of 276 pathologically confirmed SMM patients seen at the Mayo Clinic from 1970 to 1995, baseline serum samples obtained within 30 days of diagnosis were available in 273. Results: At a median follow-up of surviving patients of 12.4 years, transformation to active disease has occurred in 161 (59%) patients. An abnormal FLC ratio was present at baseline in 90% of patients. The best break-point for predicting risk of progression was a FLC ratio less than or equal to 0.125 or greater than or equal to 8 (hazard ratio, 2.3; 95% CI, 1.6–3.2) [Figure 1]. The extent of abnormality of FLC ratio was independent of SMM risk categories defined by number of plasma cells in the bone marrow and size of serum M-proteins (bone marrow plasma cells ≥ 10% and serum M protein ≥ 3 g/dL; bone marrow plasma cells ≥ 10% but serum M protein &lt; 3 g/dL; and serum M protein ≥ 3 g/dL but bone marrow plasma cells &lt; 10%). Incorporating the FLC ratio into the risk model, the division of patients into high-, intermediate-, and low-risk groups is 28, 42, and 30% with 5 year progression rates of 76, 51, and 25%, respectively [Figure 2]. Conclusions: The serum immunoglobulin FLC ratio is an important additional determinant of clinical outcome in patients with SMM. Figure Figure Figure Figure
Genomic Abnormalities Among African Individuals with Monoclonal Gammopathies Using Calculated Ancestry
Polley, Mei‐Yin C. , Pearce, Kathryn E., Baird, Michael L., Colby, Colin , Benson, Joanne, Asmann, Yan W. , Therneau, Terry M. , Vachon, Celine M. , Stewart, A. Keith, Kumar, Shaji , Baughn, Linda B. , Larson, Dirk R. , Elhaik, Eran , Benson, Joanne T., Li, Zhou, Cerhan, James R. , Vachon, Celine M. , Bergsagel, P. Leif , Dispenzieri, Angela , Rajkumar, S. Vincent

Blood | October 14, 2019 | Volume: 132 | Issue: Supplement 1 | Pages: 4458-4458

10.1182/blood-2018-99-117382 Get It

Abstract Monoclonal gammopathies, including multiple myeloma (MM), represent a group of plasma cell (PC) disorders that comprise of mostly incurable hematopoietic malignancies with an increasing incidence in the US. Previous epidemiological studies demonstrated a 2-3 fold higher incidence of monoclonal gammopathy of undetermined significance (MGUS) and a similarly higher incidence of MM along with a ~4-year younger age of onset among African Americans (AA) compared to European Americans (EAs) (Fonseca, Leukemia, 2017). This suggests a possible ancestral-associated genetic predisposition of AAs to the development of monoclonal gammopathies (Landgren, Blood, 2006). When access to care is equal, AAs have a better overall survival compared to EAs suggesting that AAs may have a genetic predisposition that renders them better responders to treatment or have more favorable cytogenetic subtypes of MM (Waxman, Blood, 2010). Previous efforts to understand this disparity have relied on self-reported race rather than genetic ancestry. We hypothesize that quantifying genetic ancestry is necessary to fully understand the genetic mechanisms of racial disparities of monoclonal gammopathies. We describe our study of 881 patients with monoclonal gammopathies who had undergone uniform testing to identify MM-specific cytogenetic abnormalities. DNA from the bone marrow samples was genotyped on the Precision Medicine Research Array. Biogeographical ancestry was assessed using the Geographic Population Structure Origins tool, which provides the ancestral breakdown of 36 admixture components for each individual representing different geographic regions and outputs admixture proportions corresponding to those ancestries (Elhaik, Nat Commun, 2014). We evaluated whether an increase in the percentage of African Ancestry altered the odds of any primary cytogenetic abnormality. We demonstrated that a 10% increase in the percentage of African ancestry was associated with a 6% increase in the odds of detecting either an t(11;14), t(14;16) or t(14;20) (odds ratio = 1.06, 95% CI: 1.02 - 1.11; p-value = 0.05). Although we observed an increase in the odds of each of the individual translocations with 10% increase in African ancestry, l t(11;14) (OR=1.03) t(14;16) (OR=1.11) and t(14;20) (OR=1.10), these three abnormalities were combined to achieve greater statistical power. The differences in cytogenetic abnormalities were most striking among individuals with ≥80.0% African (n=120) compared to individuals with <0.1% African ancestry (n=235). Using these cutoff values comparing the ≥80.0% and <0.1% African ancestry cohorts, there was a higher prevalence of t(11;14), t(14;16) and t(14;20) (51% vs. 33%, respectively, p-value=0.008) and a lower prevalence of trisomies (with or without IgH translocations) (48.3% vs. 61.3%, respectively, p-value=0.066). In addition, the ≥80% African ancestry cohort also displayed a slightly lower prevalence of monosomy 13/13q deletion compared to the cohort with <0.1% African ancestry (34.2% vs. 38.7%, respectively, p-value=0.021). Further, we observed a significantly higher prevalence in the proportion of females with monoclonal gammopathies among the ≥80% African ancestry cohort compared to the cohort with <0.1% African ancestry (56.7% vs. 42.1%, respectively, p-value=0.028). We complement our past studies that relied on self-reported race and characterized patients' demographic and uniformly collected cytogenetic data in relation to genetically defined African ancestry. We demonstrate the prevalence of having one of three specific subtypes (i.e., t(11;14), t(14;16), or t(14;20)) was significantly higher in those with highest (≥80%) compared to lowest (<0.1%) African ancestry demonstrating African ancestry is associated with a subtype distribution of MM that differs from non-African individuals. These differences were only revealed after analysis of individuals with the highest and lowest percentage of African ancestry. Since 38.3% of the individuals with ≥80% African ancestry have the favorable t(11;14) translocation (in comparison to 26.8% of <0.1% African individuals), this finding may explain improved survival with equal access to care. Understanding the genetic mechanisms of this disparity is a fundamental step to understanding differences in incidence and outcomes of patients with monoclonal gammopathies. Disclosures Elhaik: DNA Diagnostics Center: Consultancy. Baird:DNA Diagnostics Center: Employment. Cerhan:Jannsen: Other: Scientific Advisory Board; Nanostring: Research Funding; Celgene: Research Funding. Stewart:Amgen Inc., BMS, Celgene, Takeda, Roche, Seattle Genetics, Janssen, Ono: Consultancy; Amgen Inc., Celgene, Roche, Seattle Genetics: Research Funding. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Kumar:Novartis: Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding.
The Biologic and Analytic Variability of Serum Protein Electrophoresis M-Spike, Nephelometric Ig Quantitation, Serum FLC Quantitation, and Urine M-Spike in Monoclonal Gammopathies.
Snyder, Melissa R. , Kyle, Robert A. , Benson, Joanne, Katzmann, Jerry A., Dispenzieri, Angela , Rajkumar, S. Vincent , Benson, Joanne T.

Blood | October 9, 2019 | Volume: 114 | Issue: 22 | Pages: 1803-1803

10.1182/blood.v114.22.1803.1803 Get It

Abstract Abstract 1803 Poster Board I-829 Background Plasma cell proliferative disorders are monitored by a variety of methods. Serum protein electrophoresis (SPEP) and/or urine PEP M-spike quantitation are commonly assessed in patients with monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM), and multiple myeloma (MM) to determine disease progression, response, or relapse. Serum immunoglobin (Ig) concentrations can be quantitated when the M-spike is large or if the migration is obscured within the SPEP beta fraction. Serum FLC quantitation provides a rapid indicator of response, will detect the rare occurrence of FLC escape, and will allow disease monitoring in the absence of a measurable serum or urine M-spike. The International Myeloma Working Group (IMWG) has recommended that the serum and urine M-spike should be used to monitor disease, and that FLC quantitation should be used only if there is no measurable disease by electrophoresis and if the monoclonal FLC concentration is greater than 10 mg/dL in the context of an abnormal FLC K/L ratio. We have studied serial samples in clinically stable patients in order to assess the total variability (analytic and biologic) of these assays and to confirm the IMWG recent recommendations. Methods Serial data from stable MGUS patients (n=35) were identified by the availability of all 3 serum test results (M-spike, Ig, FLC) in at least 4 serial samples that were obtained 9 months to 5 years apart and whose serum M-spikes varied by less than 25%. For MM (n=60) and SMM (n=48) the samples were within 9-15 months and serum M-spikes varied by less than 0.5 g/dL. Among the 60 MM, 48 SMM, and 35 MGUS patients, there were 23, 41, and 18 patients with measurable disease by serum M-spike (i.e. M-spike >1 g/dL); 19, 10, and 10 patients with an evaluable FLC (i.e. monoclonal FLC > 10 mg/dL and an abnormal FLC ratio); and 5, 5, and 1 patient with an evaluable urine (i.e. M-spike > 200mg/24 hr). The FLC data was analyzed as the involved FLC concentration (iFLC), the difference between the involved and uninvolved FLC concentration (dFLC), and the FLC K/L ratio (rFLC). The coefficients of variability (CV) were determined for each methodology in each patient sample set, and the average CVs were determined. Igs were quantitated by immunonephelometry using a Siemens BNII and Siemens reagent sets; kappa and lambda FLC were quantitated using a Siemens BNII and Freelite reagent sets from The Binding Site; M-spikes were quantitated using Helena SPIFE SPE and reagent sets. Results The CVs for the Ig quantitation, SPEP M-spike, FLC quantitation, and urine M-spike in each of the patient groups are listed in the table: Our laboratory's interassay analytic CV for replicate samples are 4-5% for Ig quantitation, 6-8% for SPEP M-spikes, 6-7% for FLC quantitation, and 5-7% for urine M-spikes. The analytic CVs of the methods are similar, but the total (analytic + biologic) CVs are very different. The samples have been selected by restricting the variability of serum M-spike values; when we apply the same criteria to the IgG quantitation, the IgG total CV comes closer to the serum M-spike CVs. The remaining differences, however, may be due to biologic variability contributed by polyclonal Ig. The total CV for iFLC is similar to the urine M-spike CV and suggests a previously unrecognized large biologic CV for serum FLC. The iFLC and dFLC CVs were comparable but were smaller than the rFLC CV. Conclusion The variability of the serum and urine M-spike, Ig, and FLC measurements confirm the IMWG recommendations for patient monitoring. If a patient has a measurable M-spike >1 g/dL, then the serum M-spike should be followed. If there is no measurable disease, then the iFLC can be monitored, provided that the rFLC is abnormal and the iFLC concentration is >10 mg/dL. Although the number of patients with evaluable urine M-spikes in this study is small, larger studies may confirm the utility of serum FLC compared to urine M-spike for monitoring patients with monoclonal gammopathies. Disclosures No relevant conflicts of interest to declare.
Screening Panels for Detection of Monoclonal Gammopathies
Katzmann, Jerry A., Kyle, Robert A. , Benson, Joanne, Snyder, Melissa R, Lust, John A., Rajkumar, S. Vincent , Dispenzieri, Angela , Benson, Joanne T., Larson, Dirk R. , Snyder, Melissa R, Rajkumar, S Vincent , Dispenzieri, Angela

Clinical Chemistry | June 12, 2009 | Volume: 55 | Issue: 8 | Pages: 1517-1522

10.1373/clinchem.2009.126664 Get It

Abstract Background: The repertoire of serologic tests for identifying a monoclonal gammopathy includes serum and urine protein electrophoresis (PEL), serum and urine immunofixation electrophoresis (IFE), and quantitative serum free light chain (FLC). Although there are several reports on the relative diagnostic contribution of these assays, none has looked at the tests singly and in combination for the various plasma cell proliferative disorders (PCPDs). Methods: Patients with a PCPD and all 5 assays performed within 30 days of diagnosis were included (n = 1877). The diagnoses were multiple myeloma (MM) (n = 467), smoldering multiple myeloma (SMM) (n = 191), monoclonal gammopathy of undetermined significance (MGUS) (n = 524), plasmacytoma (n = 29), extramedullary plasmacytoma (n = 10), Waldenström macroglobulinemia (WM) (n = 26), primary amyloidosis (AL) (n = 581), light chain deposition disease (LCDD) (n = 18), and POEMS syndrome (n = 31). Results: Of the 1877 patients, 26 were negative in all assays. Omitting urine from the panel lost an additional 23 patients (15 MGUS, 6 AL, 1 plasmacytoma, 1 LCDD), whereas the omission of FLC lost 30 patients (6 MM, 23 AL, and 1 LCDD). The omission of serum IFE as well as urine lost an additional 58 patients (44 MGUS, 7 POEMS, 5 AL, 1 SMM, and 1 plasmacytoma). Conclusions: The major impact of using a simplified screening panel of serum PEL plus FLC rather than PEL, IFE, and FLC is an 8% reduction in sensitivity for MGUS, 23% for POEMS (7 patients), 4% for plasmacytoma (1 patient), 1% for AL, and 0.5% for SMM. There is no diminution in sensitivity for detecting MM, macroglobulinemia, and LCDD.
Immunoglobulin free light chain ratio is an independent risk factor for progression of smoldering (asymptomatic) multiple myeloma
Dispenzieri, Angela , Kyle, Robert A. , Katzmann, Jerry A., Therneau, Terry M. , Benson, Joanne, Clark, Raynell, Melton, L. Joseph, Kumar, Shaji , Fonseca, Rafaël , Jelinek, Diane F., Rajkumar, S. Vincent , Larson, Dirk R. , Benson, Joanne T., Gertz, Morie A. , Rajkumar, S Vincent , Dispenzieri, Angela , Fonseca, Rafael

Blood | October 17, 2007 | Volume: 111 | Issue: 2 | Pages: 785-789

10.1182/blood-2007-08-108357 Get It

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 ≥ 10% and serum M protein ≥ 3 g/dL; BMPC ≥ 10% but serum M protein < 3 g/dL; and serum M protein≥ 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.