Site icon Fasano Underwriting

Plasma Cell Disorders

itm21stadmin

A woman in a lab coat is looking through a microscope. She is wearing gloves and a lab coat

written by Rahul Nawander, MD

Plasma cell disorders are age-related hematologic conditions that present interpretive challenges for life expectancy underwriting.

This article offers a thorough overview of plasma cell disorders, diagnostic criteria, prognostic indicators, treatment options, mortality, and most importantly, underwriting implications.

Understanding Plasma Cell Disorders

Plasma cells are antibody-producing white blood cells derived from B-lymphocytes, primarily residing in the bone marrow and lymphatic tissues. In plasma cell disorders, a single aberrant plasma cell proliferates clonally, generating large quantities of monoclonal antibodies, referred to as M-protein. Normally, antibodies consist of two pairs of protein chains: one heavy and one light. However, in monoclonal gammopathies, the produced antibody is often incomplete, consisting of only heavy or light chains, illustrated in Figure 1. These abnormal proteins suppress normal immune function and can cause systemic damage, particularly to the bones and kidneys.

Figure 1: Clonal proliferation and formation of monoclonal bodies (M-protein)

The common plasma cell disorders include:

Diagnostic Evaluation

The diagnosis of plasma cell disorders hinges on a combination of laboratory findings and clinical symptoms.

Blood Tests

Urinalysis

Bone Marrow Biopsy

Clinical Indicators

Clinical symptoms commonly include fatigue, anemia, bone pain, neuropathy, hypercalcemia, weight loss, renal dysfunction, or features suggestive of amyloidosis (e.g., macroglossia, NT-proBNP elevation, or cardiomyopathy).

CRAB Criteria

CRAB is a vital acronym representing organ damage:

Differentiating Plasma Cell Disorders

Diagnoses of exact type of plasma cell disorder – MGUS, SMM, and MM relies on a combination of clinical presentation and specific laboratory criteria summarized in Table 1.

Table 1: Laboratory diagnostic criteria for MGUS, SMM, and MM

In addition to the standard diagnostic criteria, cytogenetic abnormalities identified through molecular testing play a critical role in guiding both treatment decisions and prognostic assessment. Unlike traditional genetic testing, which may explore inherited mutations, cytogenetic analysis focuses on acquired chromosomal abnormalities such as deletions, translocations, or duplications that influence disease behavior, treatment response, and risk of progression.

Monoclonal Gammopathy of Undetermined Significance (MGUS)

MGUS is typically an asymptomatic condition that is often identified incidentally during laboratory evaluations for unrelated concerns such as anemia, peripheral neuropathy, or chronic pain. It affects approximately 3% of individuals over age 50 and 5% of those over age 70, with an estimated annual progression risk of 1% to multiple myeloma (MM) or related clonal plasma cell disorders.

MGUS is more prevalent in the United States compared to Europe and Asia. Notably, a study of U.S. veterans found a significantly higher prevalence among African American individuals (8.6%) compared to White individuals (3.0%), highlighting a potential racial disparity in disease susceptibility.

Risk of Progression

The long-term risk of progression from MGUS to MM varies widely from 5% to 58% over 20 years depending on the presence of specific risk factors. Two validated risk stratification models are commonly used:

Table 2: Risk of progression from MGUS to MM

In rare cases, MGUS may also evolve into other plasma cell or lymphoid malignancies, such as Waldenström macroglobulinemia (WM) or B-cell lymphomas, which typically carry a lower mortality risk than MM.

Monitoring and Management

Treatment is not recommended for MGUS; instead, the condition is monitored based on the individual’s risk classification:

While MGUS itself is not life-threatening, its presence can signal underlying plasma cell clonality. Additionally, comorbid conditions such as chronic kidney disease, cardiovascular disease, or stroke may elevate mortality risk.

A long-term study using NHANES data (mean age: 62 years) observed a modest increase in all-cause mortality among individuals with MGUS: 1.2-fold higher (95% CI: 1.02–1.41) than the general U.S. population without MGUS, as illustrated in Figure 2.

Figure 2: Survival in NHANES participants with and without MGUS (Reproduced from Ji, et al. 2023).

Underwriting Implications

MGUS is typically benign and asymptomatic, but underwriters must assess risk factors such as M-protein levels, immunoglobulin subtype, and abnormal FLC ratios to identify individuals with higher likelihood of progression to multiple myeloma. Regular monitoring frequency and comorbid conditions should also be considered when evaluating overall mortality risk.

Smoldering multiple myeloma (SMM)

SMM is considered a precursor to MM, positioned biologically and clinically between MGUS and overt MM. However, it is recognized as a distinct clonal plasma cell disorder characterized by a significantly increased risk of progression to MM. Unlike MGUS, individuals diagnosed with SMM present higher levels of monoclonal protein and a greater percentage of plasma cells in the bone marrow. It is differentiated from MM by the absence of myeloma-defining events, such as CRAB features or end-organ damage.

The prevalence of SMM is estimated at approximately 0.5% among individuals over age 40 years. The annual risk of progression from SMM to MM ranges from 10% to 20%, underscoring the importance of appropriate risk stratification.

Risk Stratification Models

Three widely recognized models help estimate the risk of SMM progressing to MM are: Mayo Clinic 2008, Mayo Clinic 2018 (20/2/20 model), and the International Myeloma Working Group (IMWG) 2020 model. These models assess various combinations of FLC ratios, M-protein levels, bone marrow plasma cell burden, and cytogenetic abnormalities to assign risk classes and predict time to progression, see Table 3.

Table 3. Risk Stratification Models for SMM Progression.

Evolving Role of Early Intervention

Historically, treatment for SMM was deferred until signs of progression emerged, particularly in individuals classified as low- or intermediate-risk. These patients were monitored closely with blood work every 4 months and annual imaging (low-dose whole-body CT or MRI). However, recent studies support early intervention, even in lower-risk groups, to delay or prevent progression to symptomatic MM.

In a 2020 study (Lonial et al.), treatment significantly reduced progression rates compared to observation at 1, 3, and 5 years:

Prognosis and Survival

Despite being asymptomatic at diagnosis, SMM carries a substantial risk of mortality, primarily due to its high progression potential. A 2023 study (Sandecka et al.) evaluating individuals stratified by the Mayo 20/2/20 criteria found a 7-year survival rate of:

Figure 2: Overall survival in SMM (Mayo 20/2/20), reproduced from Sandecka, et al (2023).

Underwriting Implications

SMM is an asymptomatic but high-risk clonal plasma cell disorder with a significant likelihood of progression to multiple myeloma, especially in individuals classified as high-risk by validated models such as Mayo 2008, Mayo 20/2/20, and IMWG 2020. Underwriters should closely evaluate risk stratification scores, frequency of follow-up testing, and any evidence of evolving disease. Individuals with high-risk SMM or those recently initiating treatment require cautious assessment, with particular attention to treatment response and stability over time. A durable response lasting more than 3 years may indicate improved prognosis.

Multiple Myeloma

Multiple myeloma (MM) is a rare but aggressive hematologic malignancy, most commonly diagnosed in individuals over the age of 70. It is characterized by the malignant proliferation of monoclonal plasma cells within the bone marrow, leading to extensive skeletal complications, including osteolytic lesions, osteopenia, and pathologic fractures.

According to the U.S. Surveillance, Epidemiology, and End Results (SEER) registry, approximately 36,000 new cases of MM are diagnosed annually, with an estimated 13,000 related deaths each year – underscoring its high mortality burden.

The predisposing risk factors of MM include MGUS, SMM, and agent orange exposure.

In addition to the diagnostic criteria listed in Table 1, MM frequently presents with the following symptoms:

These manifestations are often accompanied by measurable monoclonal protein in serum or urine and a high percentage of bone marrow plasma cells.

Staging: The R2-ISS System

While the Revised International Staging System (R-ISS) was traditionally used to classify MM, recent advances have led to the adoption of the Second Revision of the International Staging System (R2-ISS), which provides enhanced prognostic granularity by incorporating biochemical and cytogenetic data, see Table 4 and Table 5.

Table 4: Prognostic Factors and Point Allocation – R2-ISS

Table 5: R2-ISS Stage and 5-year Survival (Source: D’agostino Mattia et al., 2022)

Treatment & Prognosis

Management of MM typically involves a combination of chemotherapy and hematopoietic cell transplantation (HCT) – the latter generally performed in individuals under 77 years of age. Despite advances in therapeutic options, MM remains incurable, with frequent relapses necessitating multiple lines of treatment (LOTs).

The number of LOTs correlates directly with survival outcomes. In a study by Braunlin et al. (2021), individuals who responded well to the first LOT often achieved remission durations exceeding 6-7 years. In contrast, those undergoing four or more LOTs had a significantly diminished median life expectancy of 3–4 years, reflecting the cumulative impact of treatment resistance and disease progression, see Figure 3

Figure 3: Survival in MM based on LOTs (Reproduced from Braunlin et al, 2021)

Underwriting Implications

Multiple myeloma is a high-risk, incurable malignancy with significant morbidity and mortality, particularly in individuals over age 70. Underwriters should evaluate disease severity using R2-ISS staging and assess the presence of high-risk cytogenetic abnormalities, organ involvement (e.g., anemia, renal insufficiency, bone lesions), and treatment history. The number of treatment lines (LOTs) and response durability are critical markers. Prolonged remission following first-line therapy suggests a more favorable prognosis, whereas multiple relapses and advanced staging significantly elevate mortality risk. Thorough review of staging, laboratory data, treatment response, and comorbidities are essential for prudent risk stratification.

Waldenström Macroglobulinemia (WM)

WM is a rare lymphoplasmacytic B-cell malignancy, diagnosed in approximately 3 individuals per million annually in the United States. It predominantly affects the White population, with a median age at diagnosis of 70 years.

WM is characterized by the overproduction of IgM monoclonal protein (macroglobulin), which increases serum viscosity and can lead to multisystem involvement.

Common clinical manifestations include:

Despite its potential complications, WM generally carries a favorable prognosis. Five-year survival rates vary by risk category (Source: Amaador Karima et al., 2022):

Heavy Chain Diseases

A type of rare B-cell proliferative disorder that occurs when clonal plasma cells produce incomplete antibodies in which M-protein is formed without a bound light chain.

There are three primary subtypes, each associated with different immunoglobulin classes and clinical behaviors:

These disorders are diagnostically challenging due to their rarity and nonspecific presentations. Accurate identification often requires serum and urine electrophoresis, immunofixation, and biopsy.

Underwriting Summary

Plasma cell disorders are predominantly seen in older adults and represent a spectrum ranging from benign, asymptomatic conditions to aggressive, high-mortality malignancies. Underwriters must exercise heightened vigilance when assessing such individuals, as these disorders often involve immune dysregulation, progressive organ damage, and complex diagnostic profiles.

Interpretation of specialized tests such as serum protein electrophoresis (SPEP), immunofixation electrophoresis (IFE), and free light chain (FLC) assays are critical for distinguishing indolent entities like MGUS from higher-risk conditions such as SMM and multiple myeloma (MM). Misclassification can lead to substantial underestimation of mortality risk.

Key underwriting considerations include:

A comprehensive review of the individual’s medical records, laboratory findings, imaging, and clinical course is essential. Plasma cell disorders can be deceptively subtle in early stages; therefore, proactive risk stratification is crucial. Evaluations should be grounded in both the current burden and future progression potential of the disease to ensure sound, risk-appropriate underwriting outcomes.

 

 

 

References & Additional Reading:

  1. Mellor, Paul. “Plasma cell disorders.” August’s Consultations in Feline Internal Medicine, Volume 7(2015): 535.
  2. Kyle, Robert A., and S. Vincent Rajkumar. “Monoclonal gammopathy of undetermined significance and smouldering multiple myeloma: emphasis on risk factors for progression.” British journal of haematology5 (2007): 730-743.
  3. International Myeloma Working Group. “International Myeloma Working Group (IMWG) Criteria for the Diagnosis of Multiple Myeloma: International Myeloma Working Group; 2014 [updated 29th October 2015].”
  4. Rajkumar, S. Vincent. “Updated diagnostic criteria and staging system for multiple myeloma.” American Society of Clinical Oncology Educational Book36 (2016): e418-e423.
  5. Kwaan, Hau C. “Hyperviscosity in plasma cell dyscrasias.” Clinical hemorheology and microcirculation1 (2013): 75-83.
  6. Yee, Andrew J., Karen M. Winkfield, and Noopur S. Raje. “Plasma cell dyscrasias.” Radiation Medicine Rounds: Hematologic Malignancies. New York: Demos Medical Publishing(2012): 473-88.
  7. Ferla, Valeria, et al. “Monoclonal Antibodies in Smoldering Multiple Myeloma and Monoclonal Gammopathy of Undetermined Significance: Current Status and Future Directions.” Pharmaceuticals7 (2024): 901.
  8. Landgren, Ola, et al. “Monoclonal gammopathy of undetermined significance (MGUS) consistently precedes multiple myeloma: a prospective study.” Blood, The Journal of the American Society of Hematology22 (2009): 5412-5417.
  9. Landgren, Ola. “Advances in MGUS diagnosis, risk stratification, and management: introducing myeloma-defining genomic events.” Hematology1 (2021): 662-672.
  10. Ji, Mengmeng, et al. “Mortality in the US populations with monoclonal gammopathy of undetermined significance.” JAMA oncology9 (2023): 1293-1295.
  11. Lonial, Sagar, et al. “Randomized trial of lenalidomide versus observation in smoldering multiple myeloma.” Journal of Clinical Oncology11 (2020): 1126-1137.
  12. Sandecka, Viera, et al. “Clinical characteristics and outcomes in risk-stratified patients with smoldering multiple myeloma: data from the Czech Republic Registry of Monoclonal Gammopathies.” Blood Cancer Journal 13.1 (2023): 153.
  13. D’agostino, Mattia, et al. “Second revision of the International Staging System (R2-ISS) for overall survival in multiple myeloma: a European Myeloma Network (EMN) report within the HARMONY project.” Journal of clinical oncology29 (2022): 3406-3418.
  14. Braunlin, Megan, et al. “Trends in the multiple myeloma treatment landscape and survival: a US analysis using 2011–2019 oncology clinic electronic health record data.” Leukemia & Lymphoma2 (2021): 377-386.
  15. Brink, Mirian, et al. “Decrease in early mortality for newly diagnosed multiple myeloma patients in the Netherlands: a population-based study.” Blood cancer journal11 (2021): 178.
  16. Amaador, Karima, et al. “Primary therapy and relative survival in patients with lymphoplasmacytic lymphoma/Waldenström macroglobulinaemia: a population‐based study in The Netherlands, 1989–” British Journal of Haematology 196.3 (2022): 660-669
  17. Wahner-Roedler, Dietlind L., and Robert A. Kyle. “Heavy-chain disease.” Neoplastic Diseases of the Blood(2013): 701-728.
Exit mobile version