Cancer biomarkers

What are biomarkers?

Biomarkers are molecules that indicate normal or abnormal process 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, tumour 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.

Cancer biomarkers

Learning some basic facts about DNA, RNA and proteins is helpful for understanding the importance of biomarkers in cancer. DNA, which stands for deoxyribonucleic acid, is a molecule inside the cell that carries genetic information and passes it on from one generation to the next. RNA, or ribonucleic acid, contains information that has been copied from DNA. Body cells make several different types of RNA molecules that are necessary for the synthesis of protein molecules. For example, mRNA, or messenger RNA molecules, serve as templates for the synthesis of proteins from amino acid building blocks, while tRNA, or transfer RNA molecules, bring the amino acid residues to the ribosome. Inside the ribosome – an organelle where the protein is being synthesised – tRNA “reads” the mRNA template in a process called translation.

Proteins help the body function properly and are the basis of body structures such as skin and hair. They have a wide range of functions inside the human body. Certain proteins speed up chemical reactions (enzymes), others affect the functioning of the immune system (cytokines), and yet others, known as antibodies, trigger specific immune responses in response to antigens – harmful substances that the body periodically has to overcome.

Cancer biomarkers can include:

  • Proteins
  • Gene mutations (changes)
  • Gene rearrangements
  • Extra copies of genes
  • Missing genes
  • Other molecules

Biomarkers to estimate the risk of cancer

When people talk about cancer biomarkers they’re usually referring to proteins, genes, and other molecules that affect how cancer cells grow, multiply, die, and respond to other compounds in the body. In recent years, scientists have started to look at patterns of gene expression and changes in DNA as cancer biomarkers. While some cancer biomarkers can be used to predict how aggressively your cancer will grow, and are therefore useful for assessing your prognosis (outlook), the most promising use of biomarkers today is to identify which therapies a particular patient’s cancer may or may not respond to.

Caution: Your genes and your cancer biomarkers are not exactly the same thing

There are identifiable genes in some people’s DNA that can indicate an increased risk of developing certain cancers. For example, a person who inherits certain mutations in BRCA1 and BRCA2, the so-called “breast cancer genes,” has a higher risk of getting breast, ovarian, prostate, and other types of cancer.

However, most cancers are not inherited and in the majority of cases people who are diagnosed with cancer do not have any of the “cancer genes” — at least none that we can currently identify. But all cancers do have biomarkers, including genetic biomarkers. So, what’s the difference?

Your cancer has a unique version of your DNA that is different from the DNA in your healthy cells. Most of the cancer biomarkers that have been associated with treatments have to do with your tumour’s unique genes and molecular structure, rather than your own genes.

Biomarkers to inform treatment decisions

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.

Detecting and measuring biomarkers to develop a personalised anticancer treatment plan

In order to determine if, and at what levels, certain biomarkers are present in your cancer, your doctor will need to take a sample of tumour tissue and send it to a laboratory to conduct a series of advanced pathology and molecular profiling tests. Those tests will detect and measure the levels of your cancer’s specific biomarkers. Obtained information will then be matched with published research by the world’s leading cancer researchers to identify which treatments are and are not likely to work. Your doctor will then receive a report that lists all the biomarkers that have been detected in the sample, along with the treatments that have been identified as positively and negatively associated with those biomarkers. This process allows your doctor to personalise your anticancer treatment plan based on your cancer’s unique biomarker profile.

 

References

  1. Caris Life Sciences. What are Biomarkers? The Growing Importance of Biomarkers in Cancer. 2017 [cited 16 July 2017]. Available from: [URL link]