KRAS Testing for Colorectal Cancer

Is Testing Right for Me? I Have My Test Results

KRAS Testing for Colorectal Cancer

Pros and Cons

Everyone who is deciding whether or not to get genetic testing should first ask:

  • "Why am I getting tested?"
  • "What will this test mean for me?"
  • "What are the benefits of testing?"
  • "Are there any implications I should consider?"

In general, the advantages of KRAS mutation testing outweigh the potential negative effects. Some of the concerns that are common for other types of genetic tests – like discrimination issues or the impact on family members – don't apply to this type of test.  However, genetic testing is always a choice. If you are considering KRAS testing for anti-EGFR drug response, you may want to consider some of the issues listed below.

Pros Cons
  • Testing for the most common KRAS mutations will find most of the gene changes that prevent EGFR-targeted therapy from working.
  • If a KRAS mutation is found, the results are highly reliable.
  • If you have a KRAS gene mutation, you can avoid unnecessary and costly treatment. You can also avoid the risks and side effects from EGFR-targeted therapy. Other treatment choices, like chemotherapy and additional targeted therapies, are likely to be better suited to your tumor type.
  • If you don't have a KRAS gene mutation, you may benefit from EGFR-targeted therapy (Erbitux® or Vectibix®). These drugs are highly targeted and effective against advanced colon cancer.
  • Some people find genetic testing that guides treatment choices useful when making personal decisions about such issues as medical insurance or financial planning.
  • Genetic testing won't find all KRAS gene mutations. Uncommon mutations in the KRAS gene can be missed. This is important because test results directly affect your eligibility for EGFR-targeted therapy like Erbitux and Vectibix. This means that some patients who should not get treatment with Erbitux or Vectibix may still be treated. This may lead to unnecessary side effects, risks, and cost.
  • KRAS testing doesn't look at other tumor genes, like BRAF, that can also affect how you respond to cancer treatments. Recent studies show that BRAF mutations, like KRAS mutations, cause EGFR-targeted therapy not to work. Testing for BRAF mutations is separate from KRAS testing. It should be considered when KRAS mutation testing is normal.
  • Genetic testing can be expensive.
  • Test results can lead to significant and sometimes unexpected emotional reactions. Some people may feel denied cutting-edge therapy if they are found to have a KRAS mutation. Some people may feel unsure or obligated to get targeted therapy if they don't have a KRAS mutation. Test results could change the way you view your cancer, for better or worse. You can try to anticipate how a positive or negative result may make you feel and what you may do with the information.
  • KRAS testing doesn't look for inherited gene changes that can cause colon cancer. This test only looks for specific mutations in the colon tumor or metastasis itself. If you have a family history of colon cancer or are worried you may have an inherited form of colon cancer, you should talk to your doctor or a genetic counselor. Separate testing for inherited cancer genes is available.
Next: Insurance Coverage

Do you have advanced colorectal cancer?

Yes

No

Are you considering or are you on anti-EGFR therapy (such as Erbitux® or Vectibix®)?

Yes

No

KRAS gene testing is not likely to be useful for you.

Current medical guidelines from the American Society of Clinical Oncology (ASCO) and the National Comprehensive Cancer Network (NCCN) recommend KRAS gene testing for people with advanced colorectal cancer who are considering anti-EGFR therapy. Although other tumor types have KRAS mutations, KRAS gene testing is only recommended for colorectal cancer.

KRAS gene testing may be useful for you.

Current medical guidelines from the American Society of Clinical Oncology (ASCO) and the National Comprehensive Cancer Network (NCCN) recommend that genetic testing for KRAS mutations should be done for all patients considering or who have recently begun EGFR-targeted therapy with Erbitux® (cetuximab) or Vectibix® (panitumumab) who have advanced colorectal cancer.

KRAS testing can help predict if you will respond to a treatment for colon cancer called EGFR-targeted therapy (Erbitux® or Vectibix®). Patients with a KRAS mutation in their tumor should avoid treatment with these drugs.

The table below sums up how test results can change your care.

Possible Test Results and What They Mean

Test Result Category Chance To Get This Result What This Result Means
KRAS mutation positive About 40%
  • Your colon cancer is not likely to respond to EGFR-targeted therapy.
  • Anti-EGFR therapy may make your condition worse.
  • Medical guidelines recommend avoiding treatment with Erbitux® or Vectibix®.
  • Other kinds of therapy may work better for your tumor.
KRAS mutation negative About 60%
  • Your colon cancer has a good chance of responding to EGFR-targeted therapy.
  • Depending on your situation, EGFR-targeted therapy may be used alone or combined with chemotherapy.
  • If your tumor didn't respond to earlier chemotherapy, or if chemotherapy has stopped working, you may benefit from the addition of EGFR-targeted therapy.

KRAS gene testing may not be useful for you, because you don't have advanced colorectal cancer. Advanced colorectal cancer is the only cancer for which KRAS gene testing is recommended before starting anti-EGFR therapy.

Erbitux®, an anti-EGFR therapy, is also approved for the treatment of certain head and neck cancers. However, current medical guidelines do not recommend KRAS gene testing before starting Erbitux® for these types of cancers.

Current medical guidelines from the American Society of Clinical Oncology (ASCO) and the National Comprehensive Cancer Network (NCCN) recommend KRAS gene testing for people with advanced colorectal cancer who are considering anti-EGFR therapy. Research is being done to find out whether KRAS gene testing might be helpful for other tumor types, but at this time it is not recommended for other cancer types.

KRAS gene testing may not provide information useful to you because you are not considering anti-EGFR therapy.

Current medical guidelines from the American Society of Clinical Oncology (ASCO) and the National Comprehensive Cancer Network (NCCN) recommend KRAS gene testing before starting treatment for all patients with advanced colorectal cancer. However, KRAS gene testing is mostly useful for deciding whether anti-EGFR therapy (Erbitux® or Vectibix®) is appropriate treatment. If anti-EGFR therapy is not being considered for treatment of your cancer, KRAS gene testing probably won't provide you useful information.