Importance of genetic testing in cancer diagnosis and treatment

The article was consulted by Dr. Hoang Quoc Chinh - Vinmec Stem Cell Research Institute and Gene Technology.

Cancer is one of the leading causes of death in the world. The disease causes confusion for the patient himself, his family members and the whole community. However, by performing genetic testing to find genetic mutations that cause cancer, you can recognize them early and have effective treatment.

Normally, cells in the body naturally grow, divide, and replace dead cells. However, sometimes for some reason related to genetic mutations, cells begin to divide abnormally and grow out of control.
The consequences of this process lead to the formation of a tumor (also called a tumor). Tumors can be benign (non-cancerous) or malignant (cancerous). Benign tumors are unlikely to invade other surrounding tissues. Meanwhile, malignant tumors are constantly growing, dividing uncontrollably. They invade and destroy surrounding healthy tissues, bones, and organs (invasive cancer stage). Finally, the cancer cells leave the original area, follow the lymphatic flow to move to other parts of the body and continue to form tumors in the new area (metastatic cancer stage).

There are many different factors that cause cancer. Some cancers are caused by changes in the genome, which can be passed from parent to child. Changes in genes, combined with external agents (including physical, chemical, and biological) cause gene mutations. Some gene mutations are linked to inheritance (familial cancer syndrome).
What is familial cancer syndrome?

Familial cancer syndrome (or hereditary cancer) is a condition in which certain genetic factors increase the risk of cancer. Hereditary cancers are common for cancers such as:
Breast cancer
Ovarian cancer , Lynch syndrome (hereditary non-polyposis colon cancer)
● Li-Fraumeni syndrome (bone sarcoma) , breast cancer, soft tissue sarcoma, brain tumor)
● Cowden syndrome (benign multiple tumor syndrome)
● Peutz–Jeghers syndrome (presence of polyps, benign tumors in the gastrointestinal tract, fat cells on lips and oral mucosa)

Cancer gene testing (gene mutation testing) helps to find and screen for the risk of mutations in certain genes related to cancer. From the test results, your doctor can determine your risk of cancer or the possibility of a genetic disorder (if any).
What is polygenic testing? Multigene testing using Next Generation Sequencing techniques analyzes multiple mutations on multiple genes at the same time, thus allowing most mutations to be identified in one test and at a reasonable cost. more reasonable than traditional single-gene testing. Polygenic testing, therefore, has allowed to increase the number of people who can participate in genetic cancer screening programs through the analysis of genes recommended by cancer associations worldwide.
Polygenic analysis is a type of genetic mutation test but is performed in many genes at the same time. This test is different from the usual single-gene test, which only looks for the risk of a mutation in a particular gene. Single-gene testing is often used when a known gene mutation in a family has been identified. For example, the BRCA cancer gene test looks only for changes in the BRCA1 and BRCA2 genes.

Who should have cancer genetic testing? You may consider having cancer genetic testing if you have a family history of cancer or are at high risk for cancer. Some questions to help doctors determine genetic risk of cancer:
● Have any family members been diagnosed with cancer?
● If yes, which member, what type of cancer, and at what age?
● Does anyone have a family history of birth defects?
Depending on your answer, your doctor will consider having a gene mutation test. You may need genetic counseling with a specialist or doctor with experience in oncology or genetics.

During genetic counseling you will be provided with and explained about the following
● Risk of cancer due to inherited genetic mutations.
● Who in your family needs to be tested for genetic mutations.
● What is the process like?
● Possible results and what they mean
● What to do after receiving test results.

Cancer gene testing is usually done on a blood or saliva sample of the person being tested.

When should polygenic testing be performed? Polygenic testing may be preferred in cases where
● You have a high risk of familial cancer syndrome with multiple associated mutated genes.
● You have a personal or family history of cancer, and a single gene test does not find the germ of the mutation or the results are uncertain.
What are the benefits of polygenic testing? Multigene tests look at and screen for multiple genes at once. If a gene mutation is found, this test can
● understand your cancer risk better than a single gene test.
● Help your doctor decide if you need specific cancer screenings, in addition to routine screenings.
● Helps you to know what you can do to prevent cancer.
Disadvantage of polygenic polygenes have certain disadvantages, including
● Test results are complicated and difficult to interpret.
● Results obtained include moderate or uncertain risk of cancer occurrence.
● May not know what to do when the test results are received.
You should talk to your specialist/doctor before and after genetic testing to find out what the results mean.
If a gene mutation is discovered, should I tell my family? Once you have discovered a genetic mutation, you can pass it on to your children. Besides, siblings in the family are also likely to have mutated genes.
You can completely keep your illness secret from family members. However, if they let them know this information early, maybe it will save their lives, if the accident happens. At least knowing your situation, family members can quickly undertake cancer screening, which is essential for families with a history of cancer.

How can cancer be prevented if the test results are positive for a gene mutation? In case the gene mutation test result is positive, don't panic! Get screened for cancer more often and talk to your doctor about effective cancer prevention methods. Some ways to reduce risk such as medication, surgery, and lifestyle changes will be discussed by your doctor.
Am I being discriminated against and lost benefits for my medical condition? Many people are concerned about job discrimination or denial of health insurance based on genetic mutation test results. Accordingly, the Genetic Information Non-Discrimination Act (GINA) introduced in 2008 prohibits health insurance companies from requiring customers to provide genetic testing results, or to rely on them. based on that result to make decisions about coverage, rate of receipt or adjustment of terms. In addition, GINA also does not allow employers to discriminate against any employee or candidate for reasons related to their genetic mutation status.
Note, GINA does not apply to life insurance, long-term care insurance and disability insurance.

Most cancers progress quietly. Therefore, proactively carrying out cancer gene testing and periodically screening for early detection of cancer germs is essential to protect the health of yourself and your family. Vinmec International General Hospital always deploys cancer screening and examination packages to support the diagnosis and control of health for customers, from which doctors can choose appropriate and timely treatment methods.

Reference source: Acog.org.