Were you looking instead for the Alkaline Phosphatase test, also known as ALK PHOS or ALP, used in the evaluation of liver or bone disease? If so, go to the ALP article.
The Test Sample
What is being tested?
ALK is a short name for the anaplastic lymphoma receptor tyrosine kinase gene. This test detects specific rearrangements in the ALK gene in the DNA of cancer cells and tissue. The presence of these changes makes it more likely that a person with non-small cell lung cancer will respond to a targeted drug therapy.
The ALK gene codes for a protein called anaplastic lymphoma kinase. It is part of a family of proteins called receptor tyrosine kinases that transmit signals into cells and are thought to help regulate the proliferation of nerve cells.
About 5% of people who have non-small cell lung cancer, the most common type of lung cancer, have an alteration on chromosome 2 that leads to the fusion of the ALK gene with another gene called EML4 and results in the production of an EML4-ALK fusion protein. It is a rare mutation most commonly seen in people who have never smoked or are light smokers, especially women of Asian descent.
This gene mutation and abnormal protein production 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 EGFR (epidermal growth factor receptor).
There are several different methods of testing for ALK mutations, but all of them involve evaluating either the ALK gene rearrangement or the altered ALK protein in tumor tissue.
How is the sample collected for testing?
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.