Biomarkers (short for biological markers) are biological measures of a biological state. By definition, a biomarker is "a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes or pharmacological responses to a therapeutic intervention."
Biomarkers are the measures used to perform a clinical assessment such as blood pressure or cholesterol level and are used to monitor and predict health states in individuals or across populations so that appropriate therapeutic intervention can be planned.
Biomarkers may be used alone or in combination to assess the health or disease state of an individual.
Variety of biomarkers
A wide range of biomarkers are used today. Every biological system (for example the cardiovascular system, metabolic system or the immune system) has its own specific biomarkers. Many of these biomarkers are relatively easy to measure and form part of routine medical examinations.
For example, a general health check may include assessment of blood pressure, heart rate, cholesterol, triglycerides and fasting glucose levels. Body measurements such as weight, body mass index (BMI), and waist-to-hip ratio are routinely used for assessing conditions such as obesity and metabolic disorders.
Characteristics of an ideal biomarker
An ideal biomarker has certain characteristics that make it appropriate for checking a particular disease condition. Ideally, an ideal marker should have the following features:
- Safe and easy to measure
- Cost efficient to follow up
- Modifiable with treatment
- Consistent across gender and ethnic groups
Biomarkers as health and disease predictors
Biomarkers are used to predict serious illnesses such as diabetes and cardiovascular disease. Each individual biomarker indicates whether there is a disease or health state and can be combined to provide a detailed picture of how healthy a person is and whether or not a diagnosis needs to be made.
Biomarkers in cancer detection and drug development
The principles of biomarkers in disease have been applied to the detection, screening, diagnosis, treatment and monitoring of cancer. Traditionally, anti-cancer drugs were agents that killed both cancer cells and healthy cells. However, more targeted therapies have now been developed that can be directed to kill cancer cells only, while sparing healthy cells.
The assessment of a typical biomarker in cancer helps in the development of therapies that can target the biomarker. This can minimize the risk of toxicity and reduce the cost of treatment.
In cancer research, genetic studies are valuable because genetic abnormalities so often underlie the development of cancer. Certain DNA or RNA markers may therefore help in the detection and treatment of specific cancers.
Reviewed by Sally Robertson, BSc