Also Known As
Formal Name
KRAS Mutation Analysis
This article was last reviewed on
This article waslast modified on December 29, 2018.
At a Glance
Why Get Tested?

To detect a KRAS gene mutation in tumor tissue in order to guide cancer therapy and to evaluate prognosis

When To Get Tested?

When you have colon cancer that has spread (metastatic) or non-small cell lung cancer and your health practitioner is considering an anti-EGFR drug therapy

Sample Required?

A sample of tumor tissue

Test Preparation Needed?


You may be able to find your test results on your laboratory's website or patient portal. However, you are currently at Lab Tests Online. You may have been directed here by your lab's website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab's website or portal, or contact your healthcare practitioner in order to obtain your test results.

Lab Tests Online is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.

The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

For more information, please read the article Reference Ranges and What They Mean.

What is being tested?

This test detects specific mutations in the KRAS gene in the DNA of cancer cells and tissue. The presence of these mutations may indicate that certain drugs will not be effective in treating the cancer.

KRAS is a short name for the gene v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog. It is one of a group of genes involved in a pathway called the epidermal growth factor receptor (EGFR) pathway. This complex signaling pathway involves numerous components that relay signals from outside of the cell to within the cell to help regulate cell growth, division, survival and death.

In many normal cells, binding of epidermal growth factor (EGF) to its receptor (EGFR) on the surface of the cell is an important signal to cell growth and division. Other signals in the pathway involve a class of proteins called tyrosine kinase (TK) enzymes and a protein produced by the KRAS gene. Normally, the components of the pathway interact in the regulation of cell growth and division and do not individually stimulate cell proliferation.

However, in some cancers, EGFR becomes active even in the absence of EGF, leading to uncontrolled cell growth and division. Drugs that inhibit EGFR or tyrosine kinase enzymes are often helpful for treating such cancers. Some of these cancers, though, have a mutation in the KRAS gene that produces an abnormal K-Ras protein. The abnormal protein is always active and can stimulate cell growth even in the absence of signals from EGFR and TK. In such cancers, drugs that inhibit EGFR or TK will not be effective.

KRAS mutations are found in many different types of cancers but have been most extensively studied in colon cancer and non-small cell lung cancer. Approximately 40% of colon cancers and 20% of lung cancers will have KRAS mutations.

There are several different methods of testing for KRAS mutations, but all of them involve evaluating the KRAS gene in tumor tissue.

How is the sample collected for testing?

A tumor tissue sample is obtained through a biopsy procedure or sometimes collected during a surgery. The tumor tissue is typically evaluated by a pathologist prior to testing.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

Accordion Title
Common Questions
  • How is it used?

    This test detects the presence of the most common KRAS gene mutations 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 metastatic colon 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.

  • When is it ordered?

    A KRAS mutation test is usually ordered when an individual has been diagnosed with metastatic colon 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.

  • What does the test result mean?

    If cancer tissue contains a KRAS mutation, 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.

  • Is there anything else I should know?

    Guidelines from both the American Society of Clinical Oncology and the National Comprehensive Cancer Network have recommended KRAS mutation testing prior to anti-EGFR therapy.

    Anti-EGFR drug therapies include:

  • Should everyone with cancer have KRAS mutation testing?

    Testing is not generally indicated unless a person has colon cancer or non-small cell lung cancer and a health practitioner is considering anti-EGFR drug therapy.

  • Would this testing and drug therapy be useful for other types of cancer?

    It is possible, since KRAS mutations are found in other cancers. This is a focus for medical researchers, but it may be some time before the clinical utility of the testing and therapy in other cancers is determined.

  • Is it necessary to repeat a KRAS mutation test?

    This is not usually necessary but might occur if the health practitioner thought that the first sample tested might have been insufficient. In some cases, a health care provider may order a KRAS test that detects a mutation in another part of the DNA chain or another more rare KRAS mutation. Sometimes metastatic tumors may be not be accessible or have limited tissue for testing. In these cases, a sample (if available) from an individual's primary cancer may be obtained for testing. Frequently, if the primary tumor has a KRAS mutation, so will the metastatic tumor.

  • Can this test be performed by my local laboratory?

    It may be available in some larger laboratories, but must often it will be sent to a 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.

View Sources

Lefferts, J. and Tsongalis, G. (2010 March 5). KRAS Mutation Detection: A New Look at an Old Gene. Clinical Chemistry v 56:5, 698–701 [On-line information]. Available online at through Accessed May 2012.

Franklin, W. et. al. (2012 January). KRAS Mutation Comparison of Testing Methods and Tissue Sampling Techniques in Colon Cancer. J Mol Diagn. v 12(1): 43–50. [On-line information]. Available online at through Accessed May 2012.

Anderson, S. (2011 August 15). Laboratory Methods for KRAS Mutation Analysis. Medscape Today News from Expert Rev Mol Diagn. v 11(6):635-642 [On-line information]. Available online at through Accessed May 2012.

Markman, M. (Updated 2012 March 28). Colorectal Cancer and KRAS/BRAF. Medscape Reference [On-line information]. Available online at through Accessed May 2012.

Pool, M. (2009 March 2). The Role of KRAS Mutation Testing in the Management of Colorectal Cancer. CAP [On-line information]. Available online through Accessed May 2012.

(2009 July). KRAS Mutation Testing for Anti-Epidermal Growth Factor Receptor Therapy in Colorectal and Lung Cancer. Mayo Clinic Mayo Medical Laboratories Communique [On-line information]. Available online at through Accessed May 2012.

(© 1995-2012). Test ID: KRAS KRAS Gene, 7 Mutation Panel, Tumor. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at through Accessed May 2012.

Jarboe, E. et. al. (Updated 2011 February). Colorectal Cancer. ARUP Consult [On-line information]. Available online at through Accessed May 2012.

(Reviewed 2012 May). KRAS. Genetics Home Reference [On-line information]. Available online at through Accessed May 2012.

(Reviewed 2011 December 7). Tumor Markers. National Cancer Institute [On-line information]. Available online at through Accessed May 2012.

Liu, X. et. al. (2011 February 13). KRAS Gene Mutation in Colorectal Cancer is Correlated with Increased Proliferation and Spontaneous Apoptosis. Medscape Today News from Am J Clin Pathol. v 135:245-252. [On-line information]. Available online at through Accessed May 2012.

(Revised 2012 February 17). Lung Cancer (Non-Small Cell), How is non-small cell lung cancer diagnosed? American Cancer Society [On-line information]. Available online through Accessed May 2012.

(Revised 2012 January 25). How is colorectal cancer diagnosed? American Cancer Society [On-line information]. Available online through Accessed May 2012.

(Reviewed 2009 November). KRAS Mutation Analysis. Quest Diagnostics [On-line information]. Available online at through Accessed May 2012.

Chowdhuri, S. et. al. (2012 May 8). EGFR and KRAS Mutation Analysis in Cytologic Samples of Lung Adenocarcinoma Enabled by Laser Capture Microdissection. Medscape Today News from Modern Pathology. v 25(4):548-555 [On-line information]. Available online at through Accessed May 2012.

(Reviewed Sept 7 2012) National Cancer Institute. Targeted Cancer Therapies. Available online at through Accessed September 2012.

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