An Introduction to Biomarkers in Cancer

“Biomarker” is a term often thrown around by medical professionals when discussing cancer. If you or someone you know has recently been diagnosed with stomach (gastric cancer), doctors may recommend biomarker testing. While understanding oncology and cancer biology terminology can be difficult, having a grasp of what biomarkers are and how they are used in cancer care can be crucial to making informed decisions about your health.

A biomarker, or biological marker, refers to any biological characteristic that can be measured and evaluated objectively. They can be found in your tissues, blood or other bodily fluids (e.g., saliva and urine). Examples of biomarkers used in clinical practice include your blood pressure and heart rate.

Biomarkers serve as indicators of normal or abnormal processes, conditions or diseases, such as cancer. In oncology, biomarkers can come in the form of proteins, nucleic acids (DNA and RNA) and many other biological molecules derived from your bodily fluids and tumor tissues.

These biomarkers are typically involved in cancer formation or are released due to the presence of the disease. Therefore, testing for cancer biomarkers in your blood or tissue samples can reveal important details about the cancer you’ve been diagnosed with. This information will be extremely helpful for your doctors in understanding the processes involved in the progression of your disease and in making treatment decisions.

Based on their characteristics, there are four main classes of biomarkers: molecular, radiographic, histologic and physiologic. All four classes play a critical role in narrowing down or guiding treatment-related decisions.

Molecular biomarkers

As the name suggests, these are measurable molecules found in biological samples, such as blood and tissue biopsies. An example of a molecular biomarker would be blood glucose levels, which are useful measurements in the diagnosis and management of diabetes.

Radiographic biomarkers

Also known as imaging biomarkers, these are biological features that can be identified during imaging studies and are relevant to your diagnosis. For instance, if you have stomach (or gastric) cancer, the appearance of liver lesions on a computed tomography (CT) or magnetic resonance imaging (MRI) scan are biomarkers that could indicate the presence of metastatic disease.

Histologic biomarkers

Histologic biomarkers are microbiological markers that are examined in a tissue sample under a microscope. An example would be the microscopic structure of cancer cells in a stomach tumor or polyp tissue, which is part of the staging criteria used to determine the stage of gastric cancer.

Physiologic biomarkers

Physiologic biomarkers are measurements of a particular bodily process or function. Examples include your blood pressure and heart rate.

Biomarkers can also be categorized based on their applications. Some are used to make a cancer diagnosis, while others can predict cancer aggressiveness and therapy response.

> Learn more about the types of biomarkers in cancer here

> Discover the biomarkers commonly associated with stomach (gastric) cancer

Your doctors may require you to undergo biomarker testing soon after your cancer diagnosis and usually before discussing any treatment plans. Also called molecular testing or tumor profiling, these comprehensive tests can help inform you of the types of cancer treatment that may work best for you. If you have questions about biomarker testing or are interested in it despite not being part of your routine care, please talk to your doctors and cancer care team.