What are other Names for this Test? (Equivalent Terms)
- ALK Gene Mutation Analysis Test
- ALK Gene Mutation Test
- ALK Rearrangement Analysis Test
What is ALK Mutation Analysis Test? (Background Information)
- ALK mutation is an abnormal genetic condition whereby the ALK gene, which gives instructions for an enzyme called anaplastic lymphoma kinase (ALK), is altered. This condition is associated with lung cancer
- Mutations in the ALK gene may lead to a faulty ALK enzyme. ALK is necessary for normal growth and division of epithelial cells, which line bodily surfaces such as those in the lungs
- Alterations in ALK may cause lung cancer, most commonly non-small cell lung cancer (NSCLC). NSCLC makes up about 85% of the lung cancer cases. Adenocarcinomas are the most common type of NSCLC
- The most common alteration in ALK is the EML4-ALK rearrangement. As its name implies, the EML4-ALK rearrangement arises from the fusion of the ALK gene with another gene called the EML4 gene
- Individuals with the EML4-ALK rearrangement with lung cancer are often younger than individuals whose lung cancer is the result of other factors. Furthermore, these individuals are less likely to be smokers
- The ALK Mutation Analysis Test is a genetic test that detects mutations in the ALK gene. It is used to guide treatment for NSCLC and other cancers
- Results from the ALK Gene Mutation Analysis Test may aid in the selection of therapeutic drugs, such as tyrosine kinase inhibitors (TKIs), and disqualify the usage of certain drugs
The molecular testing, in general, can be performed using a variety of methods. Some of these methods include:
- In situ hybridization technique, such as fluorescence in situ hybridization (FISH)
- Immunohistochemistry (IHC)
- Next-generation sequencing (NGS)
- Polymerase chain reaction (PCR)
- Comparative genomic hybridization (CGH)
- Karyotyping including spectral karyotyping
- mRNA analysis
- Tissue microarrays (TMAs)
- Southern blot test
- Northern blot test
- Western blot test
- Eastern blot test
The methodology used for the test may vary from one laboratory to another.
Note: Molecular testing has limitations due to the molecular method and genetic mutational abnormalities being tested. This can affect the results on a case-by-case basis. Consultation with your healthcare provider will help in determining the right test and right molecular method, based on individual circumstances.
What are the Clinical Indications for performing the ALK Mutation Analysis Test?
Following are the clinical indications for performing the ALK Mutation Analysis Test:
- Monitoring non-small cell lung cancer therapy
- Gauging potential efficacy of TKIs
- Assessing treatment options for NSCLC and other cancers
In general, the molecular genetic testing is undertaken in the following situations:
- To assist (and in some cases, confirm) the initial diagnosis
- To distinguish other tumors/conditions that have similar histological features, when examined by a pathologist under the microscope
- To help in determining treatment options
- To confirm recurrence of the tumor: Tumor recurrence can either be at the original tumor site, or at a distant location (away from the initial site)
How is the Specimen Collected for ALK Mutation Analysis Test?
Following is the specimen collection process for ALK Gene Mutation Analysis Test:
The specimen sample requirements may vary from lab to lab. Hence, it is important to contact the testing lab for exact specimen requirements, before initiating the testing process.
- Sample on which the test is performed may include:
- Fresh tumor tissue during biopsy
- Formalin-fixed paraffin-embedded solid tumor tissue (FFPE tumor tissue), often referred to as paraffin block of the tumor
- Unstained tissue slides
- Process of obtaining the sample: As outlined by the laboratory testing facility
- Preparation required: As outlined by the laboratory testing facility
- In some cases, a different source of specimen (such as peripheral blood, bone marrow biopsy specimen, or other body fluids) may be acceptable to the laboratory performing the test
- Occasionally, additional samples may be required to either repeat the test or to perform follow-up testing
- Depending on the location of testing, it may take up to 2 weeks’ turnaround time, to obtain the test results
- Many hospitals preserve the paraffin blocks for at least 7 years. In general, older paraffin blocks (over 5 years) may affect the detection of specific mutations, due to degradation of the tumor specimen over time
Cost of ALK Mutation Analysis Test:
- The cost of the test procedure depends on a variety of factors, such as the type of your health insurance, annual deductibles, co-pay requirements, out-of-network and in-network of your healthcare providers and healthcare facilities
- In many cases, an estimate may be provided before the test is conducted. The final amount may depend upon the findings during the test procedure and post-operative care that is necessary (if any)
What is the Significance of the ALK Mutation Analysis Test Result?
- A positive value for the ALK Mutation Analysis Test may disqualify certain therapeutic drugs namely, EGFR-specific TKIs, from being used to treat non-small cell lung cancer and other cancers
The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.
Additional and Relevant Useful Information:
- The prevalence in the population of an ALK mutation is between 2-7%
- The most commonly used tyrosine kinase inhibitor is imatinib. Other TKIs include lapatinib, nilotinib, and sorafenib
- Imatinib gained FDA approval in 2001. Previously, only highly toxic drugs, such as busulfan and hydroxyurea, were used
- Many laboratories may not have the capability to perform this test. Only highly-specialized labs with advanced facilities and testing procedures may perform this test
Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.
The following DoveMed website link is a useful resource for additional information:
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