KRAS Testing for Colorectal Cancer

Is Testing Right for Me? I Have My Test Results

KRAS Testing for Colorectal Cancer

What Is KRAS?

KRAS is a protein that normally turns on cell growth in short bursts when it gets a signal from another protein called EGFR. KRAS is like a switch that is usually in the "off" position. EGFR sends a message that briefly switches KRAS "on." When KRAS turns "on," it tells the cell to grow. In this way, EGFR and KRAS work together to control cell growth and development.

KRAS and Cancer

KRAS works abnormally in many kinds of cancer cells, including colon cancer. When KRAS has a mutation, the KRAS switch becomes stuck in the "on" position. EGFR isn't needed to turn KRAS on and nothing can turn KRAS off. KRAS is constantly telling the cell to grow, which may lead to out-of-control cell growth and cancer.

These mutations in KRAS start as a mistake in a single cell. They aren't inherited and don't run in families. Every time we make a new cell, we have to copy all of our genes so that the new cell has a complete set of instructions. Mistakes are commonly copied into our genes when we make new cells. These mistakes are called mutations. Once a mistake happens, every new cell made from the cell with a mistake will also have that mistake.

Mutations build up in our cells over time. Cancer is thought to happen when enough mutations happen that the cell no longer acts or grows normally. The cell grows out of control because the normal stops for cell growth no longer work right. A KRAS gene mutation is one of the mutations that can eventually lead to cancer. KRAS gene mutations play a part in causing many different kinds of cancer.

Next: Who Should Consider KRAS Testing for Colon Cancer?

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.