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Your body is full of information that can give you a clearer picture of what’s going on inside it. Sometimes you just need the right clues to understand what you’re trying to say. When it comes to cancer, biomarkers (short for biological markers) can be these indicators.
Biomarkers are useful tools to help you and your medical team understand your diagnosis, genetic makeup, and therapeutic options. Continue reading this article so you know what biomarkers are and how they can be useful if you have been diagnosed with colorectal cancer, also known as colorectal cancer.
What are biomarkers?
Biomarkers are molecules in tissues or body fluids that can be measured to determine whether a particular disease is present in the body or to determine the effectiveness of a treatment.
There are seven types of biomarkers:
- Biomarkers for susceptibility or risk assessment: Predict how likely you are to develop a particular disorder
- Diagnostic biomarkers: detect or confirm a fault
- Prognostic biomarkers: predict the likelihood that a disorder will worsen or reoccur
- Biomarker monitoring: Determine the condition of a disorder or the body’s response to treatment
- Predictive biomarkers: They are useful for predicting whether a person would respond well to certain treatments
- Biomarkers of pharmacodynamic response: indicate how the body has responded to treatments
- Safety biomarkers: Determine the level of toxicity in the body after treatment
Who needs biomarker testing?
Some biomarkers are used in routine tests, such as your blood pressure. Other types of biomarker tests may be useful for people with certain medical conditions, including cancer. Because cancer varies in each person in terms of genes or proteins, biomarker testing is helpful for healthcare providers (HCPs) to create a personalized treatment plan for your specific tumor. Your doctor can help you decide whether biomarker testing is right for you.
How are biomarkers analyzed?
For cancer patients, biomarker testing is performed by taking samples of cancer cells. This can be done by taking a sample of tissue or cells from the tumor (called a biopsy), a blood sample or fluid biopsy, a bone marrow sample, or a sample of other body fluids such as urine or saliva.
Samples of healthy cells are also sometimes taken to compare biomarker tests of healthy and cancerous cells.
What types of biomarkers are tested for colorectal cancer and when should these tests be done?
There are four common types of predictive biomarkers for colorectal cancer:
People with stage 4 colon cancer should at least be tested for these biomarkers at diagnosis, as they can help determine the most effective treatment options.
People with colorectal cancer should also be tested for microsatellite instability high (MSI-H). In most cases, this mutation is not inherited. However, in a small percentage of people, this genetic mutation is transmitted through your genes and can be caused by Lynch syndrome. Lynch syndrome can also increase your risk of many types of cancer.
During treatment, prognostic biomarker tests such as carcinoembryonic antigen (CEA) testing are helpful in determining the effectiveness of treatment and whether recurrence occurs.
If the cancer comes back, biomarker tests should be done to determine how the body would respond to new treatments and whether the cancer has spread.
What are the most common colorectal biomarkers?
MSI-H: About 15 out of 100 colorectal cancers and about 4 out of 100 stage 4 colorectal cancers have an MSI-H mutation. Surgery and immunotherapy are usually the preferred treatment options for this type of tumor.
KRAS: A mutated KRAS protein can cause uncontrollable cell proliferation and cause cancer. About 2 in 5 colon cancer tumors have a KRAS mutation. Chemotherapy and other targeted treatments are generally the most effective options for people with the KRAS mutation.
NRAS: Like KRAS mutations, NRAS mutations can cause uncontrollable cell proliferation and cause cancer. NRAS mutations only occur in about 3 to 5 out of 100 colon cancer tumors. Chemotherapy and other targeted treatments are generally the best options for a person with an NRAS mutation.
BRAF: Like KRAS and NRAS mutations, BRAF mutations can cause uncontrollable cell proliferation and cause cancer. A BRAF mutation generally means the cancer is aggressive and may be at an advanced stage. For people with a BRAF mutation, chemotherapy, other targeted treatments, or a combination of treatments may be recommended.
HER2: The HER2 biomarker measures the amount of HER2 protein secreted. Mutation of the HER2 gene means that too much of this protein is secreted, which can lead to uncontrolled cell proliferation and cancer. Cancers with a HER2 gene mutation are more common in patients without KRAS, NRAS or BRAF mutations. Treatment of cancers with biomarkers that indicate a mutation in the HER2 gene is usually done with anti-HER2 therapies, sometimes called HER2 inhibitors.
CEA: The gastrointestinal tract secretes CEA into the blood. Colon cancer cells can also secrete CEA into the blood. Because healthy adults often have low CEA levels, test results that show high levels could mean that there is a large tumor or that the cancer has spread to other places in the body.
While these are some of the most common biomarker tests for colorectal cancer, there are other biomarker tests that your doctor may also recommend.
Does insurance cover biomarker testing?
Insurance coverage for biomarker tests varies depending on the plan and state. Currently, 18 states have mandatory biomarker testing coverage laws for plans regulated by those states. Other states are introducing similar laws this year.
Talk to your doctor about what types of biomarker tests you may need and contact your insurer to find out if your tests are covered.
This educational resource was created with support from Merck.
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