Biomarker testing may help you and your doctor choose a cancer treatment for you, Biomarkers are molecules that indicate normal or abnormal processes taking place in your body and may be a sign of an underlying condition or disease. Various types of molecules, such as DNA (genes), proteins, or hormones, can serve as biomarkers since they all indicate something about your health. Biomarkers may be produced by the cancer tissue itself or by other cells in the body in response to cancer. They can be found in the blood, stool, urine, tumor tissue, or other tissues or bodily fluids. Notably, biomarkers are not limited to cancer. There are biomarkers for heart disease, multiple sclerosis, and many other diseases.
Each person’s cancer has a unique pattern of biomarkers. Some biomarkers affect how certain cancer treatments work. There are also other kinds of biomarkers that can help doctors diagnose and monitor cancer during and after treatment.
Biomarker testing is for people who have cancer. People with solid tumors and people with blood cancer can get biomarker testing.
Biomarker testing for cancer treatment may also be called:-
- tumor testing
- tumor genetic testing
- genomic testing or genomic profiling
- molecular testing or molecular profiling
- somatic testing
- tumor subtyping
A biomarker test may be called a companion diagnostic test if it is paired with a specific treatment.
Many types of biomarker tests can help select cancer treatment. Most biomarker tests used to select cancer treatment look for genetic markers. But some look for proteins or other kinds of markers.
Some tests check for one certain biomarker. Others check for many biomarkers at the same time and may be called multigene tests or panel tests. One example is the Oncotype DX test, which looks at the activity of 21 different genes to predict whether chemotherapy is likely to work for someone with breast cancer.
Some tests, called whole-exome sequencing, look at all the genes in your cancer. Others, called whole-genome sequencing, look at all the DNA (both genes and outside of genes) in your cancer. Biomarker tests called as liquid biopsies look in blood or other fluids for biomarkers from cancer cells.
Cancer biomarkers can include:
- Gene mutations (changes)
- Gene rearrangements
- Extra copies of genes
- Missing genes
- Other molecules
FUNCTIONS OF CANCER BIOMARKERS
There are many types of cancer biomarkers, and they each work differently within the body and react differently to treatments. In general, cancer biomarkers are classified by their different functions:-
(A) Biomarkers that trigger cells to grow and multiply abnormally:-
An example of this type of biomarker is the HER2 protein, which helps to control cell growth. If HER2 is “overexpressed” in cancer cells, the cells are considered “HER2-positive,” meaning they produce more of the protein than is normal. This condition can cause the cells to grow more quickly and increase their chances of metastasizing (spreading) to other parts of the body. It also means that treatments known to disrupt the HER2 signaling pathway are likely to help stop the cancer’s growth.
(B) Biomarker that support a treatment’s cellular or molecular action:-
This type of biomarker is exemplified by a gene called SPARC, which stands for Secreted Protein, Acidic, Cysteine-Rich. SPARC helps bring albumin — a type of protein found in blood, egg whites, milk, and other substances — into cells. Some chemotherapeutic drugs are bound (“packaged”) with albumin to prevent them from being dissolved in the bloodstream before they reach their target cells. Therefore, an overexpression of SPARC helps treatments bound with albumin work more effectively by bringing the treatment right into the cell.
(C) Biomarker that disrupt treatment’s cellular or molecular action:-
Some chemotherapeutic drugs are made with platinum to disrupt tumor DNA. However, there is a protein called ERCC1 that repairs tumor DNA. If biomarker testing detects high levels of ERCC1 in a patient’s tumor, platinum-based agents aren’t likely to be very effective for that patient.
Even within the above biomarker categories, there is variety. For example, molecules that trigger abnormal cell growth can come from a gene mutation or extra copies of an otherwise healthy gene within the tumor’s DNA.
HOW IS BIOMARKER TESTING PERFORM?
If you and your doctors decide to include biomarker testing in your treatment plan, they will take a sample of your cancer cells. They may take a sample during surgery if you have a solid tumor. If you aren’t having surgery, a biopsy of your tumor may be required.
If you have blood cancer or are getting a biomarker test known as a liquid biopsy, you will need to have a blood draw. If you can’t get a tumor biopsy safely, for example, because your tumor is difficult to reach with a needle, you might receive a liquid biopsy test.
Your samples will be sent to a special lab where they will be tested for certain biomarkers. The lab will create a report that lists the biomarkers in your cancer cells and if any treatments might work for you. Your health care team will discuss the results with you to decide on a treatment.
For some biomarker tests that analyze genes, you will also need to give a sample of your healthy cells. This is usually done by collecting your blood, saliva, or a small piece of your skin. These tests compare your cancer cells with your healthy cells to find genetic changes (somatic mutations) that arose during your lifetime. Somatic mutations cause most cancers and can’t be passed on to family members.