This test detects the presence of the most common KRASgenemutations in the DNA of cells in tumor tissue in order to help guide cancer treatment. KRAS mutation analysis is ordered primarily to determine if a person with metastaticcolon cancer or non-small cell lung cancer is likely to respond to standard therapy, an anti-EGFR drug therapy. Tumors with the KRAS mutation do not respond to anti-EGFR therapy.
If a person's tumor is negative for the most common KRAS mutation, tests for other less common mutations not detected by the current test may be used to help predict therapeutic responses.
A KRAS mutation test is usually ordered when an individual has been diagnosed with metastaticcolon cancer or non-small cell lung cancer and the health practitioner is considering an anti-EGFR drug therapy. It may be performed at any time prior to the initiation of treatment.
If cancer tissue contains a KRASmutation, then the affected person will not benefit from anti-EGFR drug therapies. The presence of a KRAS mutation also indicates a likely poorer prognosis, although the presence of a specific mutation cannot predict the severity or aggressiveness of an individual person's cancer.
A negative result on the KRAS test indicates that an individual's cancer may respond to anti-EGFR therapy, but the lack of a KRAS mutation as determined by the KRAS test does not ensure this. A negative test could occur when the tumor tissue sample is insufficient and/or when the cancer is heterogeneous (some cells contain the mutation and others do not). Additionally, there may be KRAS mutations that are not detected by some tests because of their particular location on a DNA chain. Other factors may also lead to resistance to anti-EGFR drugs.
This article was last reviewed on May 29, 2013. | This article was last modified on December 30, 2013.
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