At a glance

Also known as

EML4-ALK Fusion Protein; ALK Gene Rearrangement; ALK Gene Fusion

Why get tested?
To detect an ALK gene rearrangement in tumour tissue in order to guide non-small cell lung cancer (NSCLC) therapy
 
When to get tested?
When you have been diagnosed with non-small cell lung cancer and your doctor is considering a therapeutic management plan that may include an ALK kinase inhibitor such as crizotinib
 
Sample required?
A sample of tumour tissue
 
Test preparation needed?
None
 
Confused about genetics?
See our Genetics Information page
 
 

What is being tested?

ALK is a short name for the anaplastic lymphoma receptor tyrosine kinase gene. This test detects specific gene rearrangements (a form of mutation) that involve the ALK gene in the DNA of lung cancer cells and tissue. The presence of an ALK gene rearrangement makes it more likely that a person with non-small cell lung cancer (NSCLC) will respond to drug therapy targeted at the ALK kinase.

Non-small cell lung cancer includes adenocarcinoma, squamous cell carcinoma, large cell carcinoma as well as some rarer types of lung cancer. About 5 per cent of people who have NSCLC, in particular adenocarcinoma, have an inversion on the short arm of chromosome 2 which leads to the fusion of the ALK gene with another gene called EML4. This reversing of a piece of DNA results in the production of an EML4-ALK fusion protein. Less commonly, fusion of the ALK gene with other genes such as TFG or KIF5B can occur.

The abnormal production of the altered ALK protein promotes the uncontrolled growth of cancer cells but it also makes it more likely that the affected person will respond to a drug that targets the abnormal protein (an ALK kinase inhibitor, such as crizotinib) and less likely that the person will respond to tyrosine kinase inhibitors that target the epidermal growth factor receptor (EGFR) (For information on this go to EGFR Mutation Testing).

How is the sample collected for testing?
A tumour tissue sample is obtained through a biopsy procedure or sometimes collected during surgery for tumour resection. The tumour tissue is typically first evaluated by microscopic examination by an anatomical pathologist prior to ALK testing.
 
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed
 

The Test

How is it used?

ALK mutation analysis is used primarily to determine if a person with non-small cell lung cancer (NSCLC) is likely to respond to an ALK kinase inhibitor drug therapy, such as crizotinib.
Two main methods of ALK testing include:
  • Fluorescent in situ hybridization (FISH)—this method looks for the presence of an ALK gene rearrangement at the chromosomal level, it is currently the gold standard for detection of ALK gene rearrangements in NSCLC.
  • Immunohistochemistry (IHC)—this method uses antibodies to detect the presence of an altered ALK protein in the tumour. It has high sensitivity and specificity but positive results should be confirmed by FISH. 

When is it requested?

An ALK mutation test is usually requested after an individual has been diagnosed with non-small cell lung cancer (NSCLC), especially adenocarcinoma. It is typically requested along with or as a follow-up test to EGFR mutation testing. If a non-small cell lung cancer has an EGFR mutation, then the affected person is likely to respond to an anti-EGFR drug therapy (tyrosine kinase inhibitor) and further testing is usually not necessary. However, if the tumour is negative for an EGFR mutation, then the person is not likely to respond to an anti-EGFR tyrosine kinase inhibitor. ALK mutation testing is then used to determine whether the person's tumour would be likely to respond to an ALK kinase inhibitor.
 

What does the test result mean?

If the cancer tissue contains a specific ALK gene rearrangement mutation or altered ALK protein, then the affected person is likely to benefit from an ALK kinase inhibitor drug therapy such as crizotinib and is not likely to benefit from anti-EGFR drug therapies.

A person whose cancer does not have an ALK gene rearrangement is not likely to benefit from ALK kinase inhibitor drug therapy.

A person could have a false negative test result if the tumour tissue sample is insufficient and/or when the cancer is heterogeneous (some cells contain the mutation and others do not). Additionally, there may be rare ALK mutations that are not detected by routine testing that looks for only the most common mutations.
 

Is there anything else I should know?

ALK gene rearrangements are most often seen in light smokers or non-smokers with adenocarcinoma non-small cell lung cancers, especially women of Asian descent. Although this is a relatively rare mutation, the total number of people affected by lung cancer each year means that the test and potential drug therapy is applicable to many people.

A different gene rearrangement where ALK is fused with the NPM gene may be seen in some T-cell lymphomas.

Common Questions

Should everyone with lung cancer have ALK mutation testing?

Testing is not generally indicated unless a person has non-small cell lung cancer and a medical practitioner is considering ALK kinase inhibitor drug therapy.

Is it necessary to repeat an ALK mutation test?

This is not usually necessary but might occur if the medical practitioner thought that the first sample tested might have been insufficient.

Can I receive ALK kinase inhibitor drug therapy and still not benefit from it?

Yes, most people whose lung cancer has the ALK gene rearrangement will respond, but a percentage will not. Each person and each cancer is different. Also, a person may respond initially and then become resistant to the treatment.

Can I take an ALK kinase inhibitor drug therapy without being tested?

In most cases, this is not recommended. The drugs have been developed with specific associations and your lung cancer is not likely to respond if you do not meet the identified criteria.

Can this test be performed by my local laboratory?

It may be available in some larger laboratories, but most often it will be sent to a specialised reference laboratory.

Can this test be performed on my blood instead?

No, it is not the genetics of the person that is being evaluated; it is the genetic makeup of the cancer.

Is ALK mutation testing covered by Medicare?

Yes ALK mutation testing can be ordered by a specialist in the investigation of non-small cell lung cancer in relation to access to crizotinib under the Pharmaceutical Benefits Scheme (PBS).  MBS item number 73341.

Last Review Date: April 14, 2016