How Does Genetic Testing Work?

Genetic Testing for Cancer Diagnosis and Treatment


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How Does Genetic Cancer Testing Work?

In order to understand the importance of genetic testing for targeted cancer therapy, it is helpful to understand a little bit about how genes are involved in cancer development and proliferation.

  • What are genes?
    Genes are pieces of DNA (deoxyribonucleic acid) inside each of our cells.
    • DNA is the genetic "blueprint" found in each cell
    • Genes instruct our cells how to make the proteins the body needs to function
    • They affect inherited traits passed on from a parent to a child, such as hair colour, eye colour, and height
    • Genes also affect whether a person is likely to develop certain diseases, such as cancer
  • What are chromosomes?
    In humans, genes are located on 23 pairs of long strands of DNA called chromosomes.
    • One of each chromosome pair comes from the mother, and the other from the father
    • Each chromosome can contain hundreds or thousands of genes that are passed from the parents to the child
    • The genes you were born with are in every cell in your body
  • What are gene mutations?
    Changes to your genes, called mutations, play an important role in the development of cancer.
    • Mutations can cause a cell to make (or not make) proteins that affect how it grows and divides into new cells
    • Certain mutations can cause cells to grow out of control, which can lead to cancer
    • Usually several gene changes are needed before a cell becomes a cancer cell
    • Only about 5 - 10% of all cancers are thought to be related to an inherited gene mutation
DNA Strand

How are Your Genes Involved in Your Cancer?

If less than 10% of cancers are caused by inherited genetic mutations, then the vast majority of cancers are a result of gene mutations that happen sometime during a person’s life. There are two main ways a gene mutation might occur during a person’s lifetime:

  • A specific external factor, such as exposure to sunlight or tobacco
  • A completely random (i.e. no discernible cause) event occurs inside a cell

And this is where genetic tests for targeted cancer therapy come in.

Genetic tests:

  • Detect changes (mutations) in the DNA of cancer cells
  • Provide critical information about the particular mutation(s) of your cancer cell(s)
  • Help your treatment team to select the best possible treatment for you

Knowing exactly what mutations are present allows your treatment team to predict which cancer treatments will be most beneficial – and, likewise, which treatments your body won’t respond to.

How to Create the Best Cancer Treatment Plans

What is the key to creating an optimal treatment plan for your unique form of cancer? Know all the mutations that are driving your cancer (or supporting it to proliferate). In addition, ensure that the treatment you are taking to target one specific genetic mutation doesn’t lead to increased growth in another genetic mutation. It cannot be said enough: your treatment plan must take into consideration all of your gene mutations – and, significantly, their interactions with one another – in order for it to provide you with the greatest chance of success.

And this brings us back to the importance of genetic testing. In order to detect these different mutations in your cancer tissue, medical science has developed a variety of genetic tests. These tests will provide your doctor with all the genetic information they need to be able to know what specific targeted therapies will and won’t work for your form of cancer.

If you or a loved one has received a diagnosis of cancer and wants to ensure their treatment plan is optimal, please email or call us today. Our Cancer Care Research and Advocacy Specialists will get back to you within 24 hours to answer all your questions – and/or help you access the genetic tests you need.

Register for a Precision Second Opinion, to discuss your specific case.


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