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Health Line
2 days ago
- Health
- Health Line
Are Biomarker Testing and Genetic Testing the Same Thing?
Biomarker testing and genetic testing have different purposes in diagnosing colorectal cancer. The first helps doctors understand cancer's growth and spread, while the second assesses a person's inherited risk. Colorectal cancer (CRC) starts in the colon or rectum of the large intestine. It's sometimes referred to as 'colon cancer' or 'rectal cancer,' depending on the area it first develops. According to the American Cancer Society, more than 150,000 new cases of colorectal cancer are expected in 2025. It's one of the top causes of cancer-related death, while the overall risk of developing CRC for people assigned male at birth is about 1 in 24, and 1 in 26 for those assigned female at birth. Despite being one of the most common cancers globally, survival rates for CRC have improved in many parts of the world due to medical advancements in biomarker testing and genetic testing. Both biomarker testing and genetic testing in CRC involve screening for genetic mutations, but these tests have distinct purposes during the diagnosis process. You'll notice that the language used to share stats and other data points is pretty binary, fluctuating between the use of 'male' and 'female' or 'men' and 'women.' Although we typically avoid language like this, specificity is key when reporting on research participants and clinical findings. The studies and surveys referenced in this article didn't report data on or include participants who were transgender, nonbinary, gender nonconforming, genderqueer, agender, or genderless. What is biomarker testing? Biomarker testing in medicine is used to assess, predict, or monitor disease progression. Biomarkers (biological markers) are measurable biological processes, molecules, and cellular changes that provide insight into what's happening in your body at an exact moment. The presence or absence of biomarkers or their changes provides important insight into a developing or progressing medical condition. In CRC, biomarker testing, also called 'tumor testing,' is performed on cancer cells to look for tumor-specific changes. It detects the presence of acquired genetic mutations (somatic mutations), cellular changes, and DNA changes in cancer that could influence its growth and spread. CRC biomarkers can relay information about your overall outlook and whether CRC may be responsive to certain treatments more than others. What is genetic testing? Genetic testing is a specific type of biomarker testing that analyzes your DNA to determine your risk of cancer. In CRC, genetic testing looks for inherited genetic mutations or variants (called germline mutations) associated with an increased risk of CRC. Genetic testing is mainly used as a form of risk assessment. Doctors perform these tests if you have a family history of CRC or meet the criteria for an inherited cancer syndrome. If you've received a diagnosis of CRC and didn't undergo genetic testing first, your doctor may still recommend testing after a diagnosis in certain instances. These include when there's a family history of CRC or if the disease appears to follow a hereditary pattern of development. Types of testing There are several types of tests doctors run when assessing biomarkers and genetic risk in CRC, including: Single gene: This looks for an isolated gene. Panel test: This screens multiple genes at once. Whole-genome sequencing: This assesses all the DNA in a cell. Whole-exome sequencing: This screens only the components in a gene responsible for protein coding. Tumor-mutational burden: This determines the overall number of genetic changes in a tumor's DNA. Common tumor biomarkers Biomarker testing in CRC screens for various measurable tumor indicators, including genetic mutations, protein expression levels, signaling molecules, DNA sequencing patterns, antigens, and more. Common CRC tumor biomarkers your doctor may test for include: MSI-H/dMMR sidedness (which side of the colon the cancer is located on) KRAS NRAS BRAF HER2 EGFR CEA TRK fusions DPD ctDNA PD-L1 pathway WNT pathway RET VEGF CTC MMR deficiency Common genetic tests Genetic testing for CRC typically includes screening for genetic mutations relating to inherited cancer syndromes such as: Lynch syndrome familial adenomatous polyposis (FAP) MUTYH-associated polyposis Peutz-Jeghers syndrome These are inherited conditions that significantly increase your risk of developing CRC. Genes that may be screened in genetic testing for CRC risk include: MLH1 MSH2 MSH3 MSH6 PMS2 APC MUTYH POLE POLD1 NTHL1 GREM1 RNF43 (primarily used in research) RPS20 (primarily used in research) Benefits of testing Genetic testing and biomarker testing in CRC are part of precision medicine and can help improve your cancer outcomes. Genetic testing before a potential cancer diagnosis allows you and your doctor to understand your individual risk for CRC. Knowing your likelihood can help you take preventive steps to lower your overall risk of cancer and can help detect cancer in its earliest, most treatable stages. If you've received a CRC diagnosis, biomarker testing reveals details about the disease that help your doctor treat it with the most effective therapies right from the start. Certain biomarkers, for example, can indicate if CRC will be responsive to immunotherapy or monoclonal antibody therapy. Other biomarkers can help predict treatment response and monitor recurrence. Qualification criteria Anyone with a CRC diagnosis is a candidate for biomarker testing to help direct treatment planning, but not everyone requires genetic testing to determine their inherited risk. Genetic testing is typically recommended when: you have a family history of CRC or a hereditary cancer syndrome in more than one biological relative you received a CRC diagnosis before the age of 50 CRC was diagnosed in a first-degree relative younger than age 50 multiple family members have received a diagnosis of another type of cancer associated with hereditary cancer syndromes (like ovarian or stomach cancer) you've received a diagnosis of two or more primary types of cancer biomarker testing suggests a germline mutation you have a significant number of colorectal polyps How to talk with your doctor Anyone can develop CRC, so the United States Preventive Services Task Force (USPSTF) recommends screening for all adults ages 45 and over. However, you don't have to wait until you are 45 to talk with your doctor about CRC, especially if you have a family history of the condition or inherited cancer syndromes. To help make the most of this conversation with your doctor, consider these tips: Research CRC and learn as much as you can before your appointment. Talk with your parents and biological family members to verify your family medical history. Bring a written list of questions. Have a friend or loved one come with you for support and another perspective. Take notes on what your doctor says to review at home. If you've already had biomarker testing or genetic testing for CRC, questions that may be helpful to ask your doctor include: Which genes and biomarkers were tested for? Did my tests show any biomarkers or inherited mutations? What do the results of my tests mean for my CRC risk or treatment planning? Were all possible biomarkers tested for? If not, why? Will more genetic or biomarker testing be necessary?
Health Line
07-06-2025
- Health
- Health Line
Ask the Expert: Should I have Biomarker Testing – and Would it Help?
Biomarker testing in colorectal cancer can help assess inherited risk and identify characteristics that may influence the disease's growth, spread, and response to treatment. Colorectal cancer (CRC) starts in the colon or rectum of the large intestine. Your doctor may refer to it as 'colon cancer' or 'rectal cancer,' depending on where the cancer develops first, but both of these diagnoses are included under the banner of CRC. CRC is treatable, and biomarker testing is a part of precision medicine in your comprehensive treatment plan. Biomarker testing in CRC can help detect cancer in its earliest, most treatable stages. It can also provide important details about cancer after a diagnosis that influence treatment and outcomes. Dr. Smitha Krishnamurthi, a gastrointestinal oncology specialist with the Cleveland Clinic, talks with Healthline about biomarker testing and who it's recommended for. What is biomarker testing? Biomarker testing refers to testing of the colorectal cancer to find out if there are certain changes in the cancer's genes and proteins that could impact prognosis [outlook] and treatment. What are the most common biomarkers, and what do they show? Biomarkers in CRC measure a variety of different biological processes and states. Each biomarker provides important details about the cancer's growth, spread, or treatment response. DNA mismatch repair Hospital pathology labs now commonly test all initial biopsies or surgical specimens of colorectal cancer for the presence of DNA mismatch repair proteins. This is done via immunohistochemistry (IHC) staining of the slides to look for [the] expression of four mismatch repair proteins: MLH1, PMS2, MSH2, and MSH6. If one or two of these proteins are missing, then the cancer has deficient DNA mismatch repair. Microsatellite instability (MSI) This is a polymerase chain reaction (PCR) or next-generation sequencing (NGS) test [that looks] for abnormalities in microsatellite regions of the cancer DNA. The test can be done on a tumor specimen or blood (liquid biopsy). Microsatellites are short, repeated sequences of DNA. If the cancer has [atypical] DNA mismatch repair, errors will appear in microsatellite regions of DNA in the form of missing bases or extra bases added to the DNA sequence. RAS gene mutations (mutations in KRAS and NRAS genes) This testing can be performed by PCR or NGS testing of the tumor or NGS testing of blood (liquid biopsy). RAS is a very important oncogene, meaning that it is a gene that, when mutated, drives cancer cell proliferation and survival. Mutations in RAS genes are found in up to 50% of colorectal cancers. BRAF V600E gene mutation This testing can be performed by PCR or NGS testing of the tumor or NGS testing of blood (liquid biopsy). The BRAF V600E protein can also be detected by IHC. BRAF is another oncogene, so when it is mutated, it leads to cancer cell proliferation and survival. BRAF V600E mutations occur in about 8% to 10% of colorectal cancers and are more common in right-sided cancers. HER2 protein overexpression by IHC or gene amplification by NGS HER2 is another oncogene — gene amplification leads to [the] overexpression of the HER2 protein. Overexpression of HER2 leads to increased signaling via the epidermal growth factor receptor pathway, leading to cancer cell proliferation and survival. PIK3CA PIK3CA is another oncogene. Mutations in PIK3CA and a related gene, PIK3R1, lead to cancer cell proliferation and survival. Mutations in PIK3CA and PIK3R1 are typically found via NGS. PTEN PTEN is a tumor suppressor gene, [which typically] suppresses cancer growth. When the PTEN gene is mutated, the protein is not expressed, and that leads to [the] proliferation of cancer. PTEN gene mutations are typically found via NGS. Who should have biomarker testing done? All patients with colorectal cancer should have testing of their cancer for DNA mismatch repair (or microsatellite instability) soon after diagnosis. This is important for patients with cancers of all stages. Patients with early stage colorectal cancer should have testing of their cancers for mutations in PIK3CA, PTEN, and PIK3R1 by the time they finish adjuvant treatment or after surgery if [they're] not having adjuvant treatment. Patients with metastatic colorectal cancer should have next-generation sequencing of the cancer soon after diagnosis, as the results may impact the initial systemic treatment. The NGS results are also useful for identifying clinical trial eligibility. Comorbidities will not affect the results of these biomarkers, so they should not affect the timing and decision making about ordering these tests. How does biomarker testing help the treatment and outcome of a diagnosis? Biomarkers can impact your treatment choices and outcomes. They can help doctors decide which medications will be the most effective, identify inherited features in cancer, and determine if adjuvant or additional therapies would improve outcomes. Immunotherapy responsiveness It is critical to know if a cancer has deficient DNA mismatch repair (dMMR) or high microsatellite instability (MSI-H) because these cancers can respond dramatically to immunotherapy in the early stage and metastatic settings. For example, patients with rectal cancer that is dMMR or MSI-H may have a complete clinical response with immunotherapy and may be able to avoid radiation and surgery. Thus, this testing needs to be done early, before treatment starts. Identifying Lynch syndrome Another important reason for testing for dMMR or MSI-H is to identify cancers caused by Lynch syndrome. Lynch syndrome is the most common type of inherited colorectal cancer and is caused by germline mutations in the genes that code for the DNA mismatch repair proteins or in another related gene called EPCAM. Most cancers with deficient mismatch repair or MSI-H are not caused by Lynch syndrome and occur sporadically. We don't want to miss patients with Lynch syndrome, however, because they can benefit from counseling about [the] prevention of Lynch syndrome-related cancers such as uterine cancer, ovarian cancer, and gastric cancer, in addition to colorectal cancer. When a patient is diagnosed with Lynch syndrome, family members can then be tested to see if they have Lynch syndrome. Recommendations for cancer screening at early stages are made for individuals with Lynch syndrome, and early screening can be lifesaving. Identifying treatment resistance Mutations in KRAS and NRAS make cancers resistant to anti-epidermal growth factor receptor therapy. Cancers with KRAS G12C mutations can be treated with a regimen that targets this mutation (adagrasib plus cetuximab or sotorasib plus panitumumab). There are also many clinical trials now studying RAS gene inhibitors in patients with metastatic colorectal cancer that have been previously treated. Cancers with BRAF V600E tend to be aggressive and less sensitive to chemotherapy. There is a Food and Drug Administration (FDA)-approved regimen targeting BRAF V600E (encorafenib plus cetuximab) in metastatic colorectal cancer that improves survival when added to first-line FOLFOX chemotherapy. It also improves survival as a second-line treatment after chemotherapy. Greater response to targeted and adjuvant therapy Metastatic colorectal cancers that demonstrate [the] overexpression or gene amplification of HER2 can be treated with a targeted regimen of tucatinib plus trastuzumab after initial chemotherapy. Another targeted treatment available for metastatic colorectal cancers that overexpress HER2 by IHC is trastuzumab deruxtecan. Patients with early stage colorectal cancer with mutations in the PIK3CA, PIK3R1, or PTEN genes should be treated with aspirin 160 milligrams daily for 3 years after adjuvant therapy or after surgery if [they're] not having adjuvant therapy. The ALASCCA trial, presented at ASCO GI [American Society of Clinical Oncology – Gastrointestinal Cancer] in 2025, compared a placebo to aspirin in this patient population and found that aspirin significantly lowered the rate of cancer recurrence at 3 years. This is rather new data. Oncologists are starting to order NGS testing for patients with early stage cancers in order to obtain this biomarker information. What should you ask your doctor? It's always OK to ask your doctor about biomarker testing and what it means for you. Important questions to consider include: Is my cancer dMMR/MSI-H? Am I a candidate for immunotherapy? Patients with early stage colorectal cancer should ask if aspirin therapy will be recommended based on biomarker testing. Patients with metastatic colorectal cancer should ask for the results of RAS/BRAF/HER2 testing and overall NGS testing results.
