how to read fish test results for multiple myeloma

Everly

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14-01-2025

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Multiple myeloma is a cancer of plasma cells in the bone marrow. A crucial diagnostic tool for multiple myeloma is fluorescence in situ hybridization (FISH). This test helps doctors determine the presence and type of genetic abnormalities associated with the disease, impacting prognosis and treatment decisions. Understanding your FISH test results is vital. This article explains how to interpret them, focusing on common chromosomal abnormalities seen in multiple myeloma. This information is for educational purposes only and should not replace consultation with your healthcare provider.

Understanding FISH Testing in Multiple Myeloma

FISH testing analyzes chromosomes within your myeloma cells. It identifies specific genetic changes, including deletions, translocations, and amplifications, which are often crucial in determining the aggressiveness of the disease and treatment response. The test uses fluorescently labeled probes to bind to specific DNA sequences on chromosomes. Under a microscope, these probes reveal changes in chromosome structure or number.

Common Genetic Abnormalities Detected by FISH

Several genetic abnormalities are commonly associated with multiple myeloma. Their presence or absence significantly influences prognosis and treatment strategies. Key abnormalities include:

• t(4;14): This translocation (exchange of genetic material between chromosomes 4 and 14) is associated with a poorer prognosis. It often indicates a more aggressive disease course.

• t(14;16): Similar to t(4;14), this translocation also suggests a more aggressive form of myeloma. Treatment approaches may differ based on the presence of this abnormality.

• t(14;20): This translocation is generally associated with a less aggressive form of the disease, often carrying a better prognosis compared to t(4;14) or t(14;16).

• del(17p): This deletion (loss of genetic material) on chromosome 17p, specifically involving the TP53 gene, is a significant indicator of poor prognosis and treatment resistance. It suggests a higher likelihood of relapse and shorter survival.

• 1q gain: An increase in the genetic material on the long arm of chromosome 1 is usually associated with a higher risk of relapse and shorter progression-free survival.

• Hyperdiploidy: This refers to having more than the usual 46 chromosomes. In multiple myeloma, hyperdiploidy often indicates a less aggressive disease course and is usually associated with a better prognosis.

Deciphering Your FISH Test Report

Your FISH test report will list the abnormalities detected. It will usually specify which abnormalities were found (or not found), the percentage of cells with each abnormality, and sometimes a qualitative assessment of the significance. For instance:

• "t(4;14) positive in 80% of cells": This indicates that the translocation between chromosomes 4 and 14 is present in a large proportion of your myeloma cells.

• "del(17p) negative": This means the deletion on chromosome 17p was not detected in the analyzed cells.

• "Hyperdiploidy present": Indicates the presence of more than 46 chromosomes.

Note: The exact terminology used in your report might vary depending on the laboratory. Always consult your healthcare provider or hematologist to understand the implications of your specific results.

What to Do After Receiving Your Results

FISH results are just one piece of information used to diagnose and manage multiple myeloma. Your oncologist will consider other factors such as:

• Your symptoms: The severity of your symptoms can affect treatment decisions.
• Laboratory results: Blood tests, such as complete blood counts and kidney function tests, provide additional insights into your overall health and disease progression.
• Bone marrow biopsy results: This provides information about the extent of plasma cell infiltration in the bone marrow.
• Other genetic tests: Additional tests, like cytogenetics or next-generation sequencing (NGS), can be performed to provide a more comprehensive understanding of the genetic makeup of your myeloma.

Your oncologist will use all of this information to create a personalized treatment plan tailored to your specific situation. Don't hesitate to ask questions and ensure you fully understand the implications of your results and the recommended treatment approach.

Conclusion

FISH testing is a critical tool for multiple myeloma diagnosis and management. Understanding the common abnormalities and how they are reported allows you to have a more informed conversation with your healthcare team. Remember that FISH results should be interpreted within the context of your overall clinical picture, and collaboration with your oncologist is crucial for optimal management. This information aims to improve understanding; always seek professional medical advice for personalized guidance.