Monitoring of Certain Cancers
Monitoring of certain cancers, like Multiple Myeloma, is a crucial aspect of oncology that relies heavily on diagnostic laboratory tests. This monitoring serves several vital purposes: diagnosing the cancer, assessing its stage, evaluating treatment response, detecting recurrence, and identifying complications.
Monitoring of Multiple Myeloma
Multiple Myeloma (MM) is a cancer of plasma cells, a type of white blood cell found primarily in the bone marrow. In MM, abnormal plasma cells (myeloma cells) multiply uncontrollably and produce large amounts of abnormal antibodies (called M-proteins or paraproteins), which can accumulate in the blood and urine, causing various complications.
Key Goals of Monitoring in Multiple Myeloma :
Diagnosis and Staging
Confirming the presence of MM and determining its extent.
Prognosis
Leads to pancytopenia (low counts of all three blood cell lines), causing anemia, increased risk of infection, and bleeding.
Treatment Response Assessment
Determining how well a patient is responding to therapy (e.g., complete remission, partial remission, stable disease, progression).
Minimal Residual Disease (MRD) Detection
Identifying very low levels of myeloma cells that remain after treatment, even if the patient appears to be in complete remission.
Relapse Detection
Identifying when the cancer has returned after a period of remission.
Monitoring for Complications
Detecting kidney damage, bone lesions, hypercalcemia, and infections.
Specific Laboratory Tests Used for Monitoring Multiple Myeloma:
Serum Protein Electrophoresis (SPEP) and Immunofixation Electrophoresis (IFE
- Purpose: Detect and quantify the abnormal M-protein (paraprotein) in the blood. SPEP separates proteins by charge and size, showing a characteristic “M-spike.” IFE identifies the specific type of immunoglobulin (e.g., IgG kappa, IgA lambda).
- Clinical Importance: Essential for diagnosis, quantifying disease burden, and monitoring treatment response. A decrease in M-protein indicates response, while an increase suggests progression.
Urine Protein Electrophoresis (UPEP) and Immunofixation Electrophoresis (IFE
- Purpose: Detect and quantify abnormal light chains (Bence Jones proteins) in the urine, which are produced by myeloma cells and can damage the kidneys.
- Clinical Importance: Crucial for patients who primarily excrete light chains (non-secretory myeloma) and for monitoring kidney involvement.
Serum Free Light Chain (FLC) Assay
- Purpose: Measures the levels of kappa and lambda free light chains in the blood and calculates their ratio. These are smaller, unbound parts of antibodies.
- Clinical Importance: Highly sensitive for diagnosis, monitoring, and detecting non-secretory myeloma. Changes in FLC levels often occur earlier than changes in M-protein. The kappa/lambda ratio is a key indicator of clonality.
Quantitative Immunoglobulins (IgG, IgA, IgM)
- Purpose: Measure the levels of normal and abnormal immunoglobulins.
- Clinical Importance: Myeloma cells suppress the production of normal immunoglobulins, leading to “immunoparesis,” which increases infection risk. Monitoring these levels helps assess immune function.
Complete Blood Count (CBC) with Differential:
- Purpose: Assess red blood cell count (for anemia), white blood cell count (for infection risk), and platelet count (for bleeding risk).
- Clinical Importance: Myeloma cells in the bone marrow can crowd out normal blood cell production, leading to cytopenias.
Serum Calcium:
- Purpose: Measure calcium levels in the blood.
- Clinical Importance: Myeloma often causes bone destruction, releasing calcium into the bloodstream, leading to hypercalcemia (high calcium), a common and serious complication.
Kidney Function Tests (Creatinine, BUN, eGFR
- Purpose: Assess kidney health.
- Clinical Importance: M-proteins and hypercalcemia can damage the kidneys, leading to kidney failure.
Beta-2 Microglobulin and Albumin
- Purpose: Detect and quantify abnormal light chains (Bence Jones proteins) in the urine, which are produced by myeloma cells and can damage the kidneys.
- Clinical Importance: Crucial for patients who primarily excrete light chains (non-secretory myeloma) and for monitoring kidney involvement.
Serum Free Light Chain (FLC) Assay
- Purpose: These are prognostic markers. Beta-2 microglobulin is a protein found on cell surfaces, often elevated in MM. Albumin is a blood protein, and low levels can indicate advanced disease.
- Clinical Importance: Used in the International Staging System (ISS) for myeloma to determine prognosis.
Lactate Dehydrogenase (LDH)
- Purpose: An enzyme that can be elevated in aggressive or rapidly growing cancers.
- Clinical Importance: Elevated LDH can indicate more aggressive disease and poorer prognosis.
Bone Marrow Aspiration and Biopsy
- Purpose: Direct examination of bone marrow for the percentage of plasma cells, their morphology, and genetic abnormalities.
- Clinical Importance: Essential for initial diagnosis, staging, and assessing response to treatment, especially for MRD.
Cytogenetics and FISH (Fluorescence In Situ Hybridization) / Molecular Testing
- Purpose: Analyze chromosomal abnormalities (e.g., deletions, translocations) and specific gene mutations in myeloma cells.
- Clinical Importance: Identify high-risk genetic features that influence prognosis and guide treatment choices
Imaging Studies
- Purpose: To assess bone lesions (e.g., X-rays, MRI, PET/CT).
- Clinical Importance: Myeloma often causes lytic (bone-destroying) lesions.
Overall Importance of Monitoring
For cancers like Multiple Myeloma, continuous and precise laboratory monitoring is indispensable. It allows oncologists to:
