Genetic Testing For Cancer Risk: How Does It Work?

There are now home-kits available for DNA testing that are intended to reveal to users their health vulnerabilities and even their risks for contracting cancer. How do such genetic testing for cancer risk work? It is useful to first understand what “DNA” is.

What Is DNA?

DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. It contains the instructions needed for an organism to develop, survive, and reproduce. These instructions are found within the structure of DNA, which is made up of two long strands forming a double helix. Each strand consists of nucleotides, which are the building blocks of DNA, containing a sugar, a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine).

Zephyris at the English-language Wikipedia, CC BY-SA 3.0, via Wikimedia Commons

Where DNA Is Found In A Cell

DNA is located primarily in the cell nucleus, where it is packaged into chromosomes. A small amount of DNA can also be found in the mitochondria, which are the energy-producing structures within cells. This mitochondrial DNA is inherited only from the mother.

OpenStax, CC BY 4.0, via Wikimedia Commons

Cancer Research UK, CC BY-SA 4.0, via Wikimedia Commons

What Is Whole Exome Sequencing In Genetic Testing?

Whole Exome Sequencing (WES) is a genomic technique that focuses on sequencing all the protein-coding regions of genes in a genome, known as the exome.  WES can identify genetic variants with typically around 99.9% accuracy.

Definition: The genome is the entire set of DNA instructions found in a cell. In humans, the genome consists of 23 pairs of chromosomes located in the cell’s nucleus, as well as a small chromosome in the cell’s mitochondria. A genome contains all the information needed for an individual to develop and function. Source: US National Human Genome Research Institute

During sequencing, the exact order of nucleotides (the building blocks of DNA) in the exonic regions is investigated. This allows scientists to see the specific sequence of genetic code and identify genetic variants and mutations that could be responsible for diseases or health conditions.

What Is The Process For DNA Testing Home-Kits?

DNA testing home-kits such as those from CircleDNA for instance, uses Whole Exome Sequencing (WES) technology to analyse the protein-coding regions of our DNA. Here is an overview of how they typically work:

1. Order the kit: Typically done online.
2. Collect the DNA sample: The kit includes a cheek swab or saliva collection tube. You collect a sample by rubbing the swab inside your cheek or spitting into the tube.
3. Send the sample for analysis: You register your sample using a unique number provided in the kit and send it back to the test kit company for analysis.
4. Process the sample: The provided DNA sample is processed in a lab where DNA is extracted and sequenced.
5. Analyse the data: The sequenced data is analysed to identify genetic variants and mutations.
6. Receive your report: After a few weeks, you receive a detailed report which includes health insights from your DNA sample analysis.

Benefits Of Genetic Testing For Cancer Risk

Studying our individual DNA helps us understand and manage our genetic risk of certain diseases through the following ways:

• Identification of Genetic Mutations: Specific changes or mutations in the DNA sequence can be linked to an increased risk of certain diseases. By identifying these mutations, scientists can predict the likelihood of an individual developing a particular condition. However, it is important to note that while the test can accurately identify genetic mutations, it does not provide a complete picture of a person’s cancer risk, as other factors like lifestyle and environment also play a significant role.
• Family History: Since DNA is inherited from our parents, studying it can reveal hereditary patterns that contribute to disease risk. This is especially important for conditions like cancer, heart disease, and diabetes.
• Personalized Medicine: Understanding a person’s genetic makeup can help tailor medical treatments and preventive measures to their unique genetic profile. This approach can improve the effectiveness of treatments and reduce adverse reactions.
• Early Detection and Prevention: By identifying genetic predispositions, individuals can take proactive steps in monitoring their health, making lifestyle changes, and undergoing regular screenings to catch diseases early or prevent them altogether.

Genetic Testing For Cancer Risk Is Not Foolproof

While DNA tests can offer valuable insights, they can sometimes provide misleading interpretations or results:

• Overestimation of Risk: Some tests might indicate a higher risk for certain diseases based on genetic markers, which can cause unnecessary anxiety. It is important to remember that genetic predisposition is just one factor among many, including lifestyle and environment.
• False Positives/Negatives: No test is perfect, and there can be errors in the analysis. A false positive might suggest a health issue that isn’t actually present, while a false negative might miss a real risk.
• Limited Context: Genetic information is complex, and a test might not account for all the variables that influence health. For example, a test might suggest dietary changes without considering individual responses to those changes.
• Ethnicity Estimates: These estimates can be inaccurate, especially for people with mixed heritage or from regions with less genetic data available. The testing pool’s diversity affects the accuracy of these estimates.

Does “Low Risk” Result Means No Cancer?

It is possible for a person who already has cancer to receive test results indicating a low genetic risk. This can happen because genetic tests primarily assess inherited genetic mutations that increase the risk of developing cancer, rather than detecting the presence of cancer itself.

Get Screened Today For Cancer And Other Health Conditions

Genetic testing for cancer and other health risks has its benefits, but it is not meant to detect the actual presence of the diseases.

Learn More: Cancer In Singapore >>

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For early detection of diseases, regular health screening is still highly recommended. You can consider health screening packages from our partners on our e-shop, or contact us for a doctor’s appointment via the button below.

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