Colorectal Cancer Biomarkers

Somatic testing looks only for changes inside the tumor, not changes happening inside your normal DNA. Somatic testing is what’s most closely associated with biomarker/tumor testing. Germline testing is genetic testing looking at mutations inherited from your biological parents and if there are changes in your DNA that predisposed you to cancer.

First of all: Way to be an informed patient! Knowledge is power! Not all physicians are up to date on biomarkers and biomarker tests that need to be run. Make sure you take reliable information to your physician and ask them to check with NCCN guidelines for biomarker testing. It’s also never too late to get a second opinion if your physician won’t listen to you and take your questions and/or requests seriously. Your current treatment plan, previous biomarker testing reports, and insurance coverage should also be taken into consideration.

Your test results for gene testing for example, will show whether your tumor has a mutation (a genetic change – positive test results) or if it is wild-type (no genetic change – negative test results – no mutation detected). Your doctor should review your test results with you and discuss how they will affect your treatment decisions. If your doctor does not bring this up, ASK. You should receive a copy of your biomarker test results, and if you did not get a copy, make sure to ask. You own your records and have a right to them.

The most common mutations in the KRAS and BRAF genes do not normally occur together. It would thus be extremely rare. If your tumor has a BRAF V600E mutation, it will most likely not be KRAS mutant, and vice versa. Non-V600 BRAF mutations commonly co-occur with KRAS/NRAS mutations, particularly BRAF D594 mutations which are second most common after BRAF V600E mutations.

If you begin receiving a treatment before knowing your tumor type, this may exclude you from future treatment options, including some clinical trials. Biomarker testing can also give insight as to whether or not you will respond to certain treatments based on the genetic changes inside your tumor. It’s worth taking the time to talk about tumor testing with your doctor before making treatment decisions, especially if you’re facing metastatic colorectal cancer.

If you’ve already started treatment prior to tumor testing, it is recommended that you still receive the testing (it could affect your current treatment plan). The hospital where you had surgery most likely retained some of your tumor tissue. Contact your surgeon and connect them with your oncology team to learn more about how to get your sample sent to a pathology lab for testing. If your tumor tissue was not saved, ask your doctor about the best way to move forward with biomarker testing.

Not usually. When you had surgery or a biopsy, some of your tumor tissue was removed and stored at the hospital. Your doctor can arrange for your tissue to be sent to a lab. The results will go to your doctor. The tissue sample tested can be from your original cancer in your colon or rectum, or from a metastatic tumor that has spread. If no tissue remains available, your doctor may suggest an additional biopsy to perform biomarker testing. If you’re getting biomarker testing with a liquid biopsy (blood), frequent blood draws will likely be required.

Your provider should be discussing biomarker testing with you, however not all providers use the word “biomarkers,” and not all providers realize it’s a term patient need to know. Your doctor may have been requesting some type of biomarker testing for you already, but did not mention or explain it. If you’re unsure if you’ve been tested for any biomarker, advocate for yourself and start the discussion. Our biomarker testing discussion guide is a great place to start.

There are multiple biomarkers that have been scientifically shown to be meaningful in colorectal cancer. While more and more biomarkers are being studied, not all are shown to have clinical relevance or benefit the patient’s treatment decision-making. While knowledge is power and biomarkers can give you a wealth of information regarding your cancer and prognosis, you need to mentally and emotionally prepare yourself for biomarker testing, as some test results will show poorer prognosis and lead to a limited number of treatment options.

Genetic testing is a type of biomarker testing, but it does not ensure that you have received all the biomarker tests necessary to make an informed treatment decision. Every colorectal cancer patient should have some type of screening for inherited cancer that’s looking for what’s been inherited from biological parents, what predisposes them to cancer. Genetic tests can be done by looking at someone’s blood to see what’s there and/or the consequence of a genetic alteration and look at the cancer itself. Tumor molecular profiling looks for genomic changes, to distinguish it from inherited genetic changes.

This means that you have received MSI testing, which is one biomarker out of many. To learn if you have received and/or need testing for additional biomarkers, you will need to check with your doctor.

If you are participating in a clinical trial, the trial may cover the cost of biomarker testing. Private individual or employer-sponsored health insurers will usually cover biomarker tests when they are “medically necessary.” You and your doctor need to be on the same page, and it needs to be clear what biomarker tests are needed for your treatment plan. Biomarker testing is standard for all patients with metastatic colorectal cancer and should be done to guide treatment decisions if your tumor has spread beyond the colon or rectum.

Some people may avoid testing due to perceived financial burden. Luckily, many labs offer patient assistance for out-of-pocket costs, and insurance companies may cover costs as well. Talk to a social worker and call your insurance provider to learn more.

In May 2017, four professional groups published evidence-based guidelines for biomarker testing for colorectal cancer. The Guideline, titled Molecular Biomarkers for the Evaluation of Colorectal Cancer Guideline from the American Society for Clinical Pathology, College of American Pathologists, Association for Molecular Pathology, and American Society of Clinical Oncology provides recommendations for mismatch repair status testing.

As of 2022, the National Comprehensive Cancer Network (NCCN) recommends microsatellite stability/instability (MSS/MSI) biomarker testing for all CRC patients, regardless of stage at diagnosis. Furthermore, they recommend KRAS, NRAS, BRAF, and HER2 biomarker testing for patients with stage IV, metastatic CRC.

There are several biomarkers without standardized recommendations. As research continues to evolve, guidelines and recommendations will also likely change to reflect the most relevant and meaningful research.

We strongly encourage you to talk with your doctor about ordering the tests. Without a physician referral, there is a potential that insurance won’t cover the testing, and it can be pricy. A doctor needs to be involved so you can take action about the results. If you need biomarker testing and your doctor refuses, we encourage you to seek a second opinion.

Sometimes you will need to advocate for yourself and start a conversation with your doctor about biomarker testing. To help guide your discussion, use this Biomarker Discussion Guide developed LUNGevity.

Biomarkers should be tested when you are first diagnosed. Testing for biomarkers at this time can help direct the best treatment for you. During treatment, you should continue to be tested for your CEAs and CA 19-9. These two biomarkers can be indicators of treatment effectiveness between scans. If you have a recurrence after being NED or if you have progression while you are on treatment, it may be a good time to be tested for your biomarkers – even if you have previously been tested. Because cancer involves mutations, biomarkers in your body may change over time. The repeated biomarker testing may reveal something new, indicating an effectiveness of a specific treatment that previously was not revealed. Make sure to ask about costs and coverage before you undergo testing.