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Predictive Genetic Test for Cancer : Are you at Risk ?

Updated: Jun 24, 2018

Tjiang W, See KS Kris




Risk is the chance that an event will happen. When talking about cancer, risk is most often used to describe the chance that a person will get cancer. It is also used to describe the chance that the cancer will come back or recur.


A cancer risk factor is anything that increases a person’s chance of getting cancer. Yet most risk factors do not directly cause cancer. Some people with several risk factors never develop cancer. And others with no known risk factors do.


General risk factors for cancer include:

  • Older age

  • A personal or family history of cancer

  • Using tobacco

  • Obesity

  • Alcohol

  • Some types of viral infections, such as human papillomavirus (HPV)

  • Specific chemicals

  • Exposure to radiation, including ultraviolet radiation from the sun


You can avoid some risk factors by stopping risky behaviors. These include using tobacco and alcohol, being overweight, and getting multiple sunburns. Other risk factors cannot be avoided, such as getting older.


According to the US National Cancer Institute’s Surveillance Epidemiology and End Results (SEER) Database, lifetime risk of developing cancer for males are : prostate cancer 1 in 9 (11.5%), lung and bronchus 1 in 15 (6.85%), colon and rectum 1 in 22 (4.49%), and for females are : breast cancer is 1 in 8 (12.41%), lung and bronchus is 1 in 17 (5.95%), colon and rectum is 1 in 24 (4.15%).


Current healthcare primarily is based on diagnosing the presence of disease and subsequently treating the disease if it is present. According to Cancer Research UK, almost half of people who get cancer are diagnosed late, which makes treatment less likely to succeed and reduces their chances of survival. In a report, 46% of all patients with cancer have their disease diagnosed when it has already reached an advanced stage. The findings have highlighted the worryingly high rates of late diagnosis, and consequently poor survival, for people with many types of cancer. Diagnosing cancer at its earliest stages, before it has had a chance to spread to other parts of the body, can have a huge effect on survival.


Predictive Genetic Testing

Predictive genetic testing is the type of testing used to look for gene mutations that might put a person at higher risk of getting certain kinds of cancer. It's "predictive" because a positive result means you have a faulty gene that raises your risk of developing cancer.


The obvious benefit of genetic testing is the chance to better understand of your risk for a certain disease. Testing is not perfect, but it can often help you make decisions about your health.


A positive test result does not always mean you will get the disease. The test can tell what mighthappen, but it cannot tell what will happen. On the other hand, a negative result does not mean you have no risk of getting the disease. And risk can change over time due to lifestyle choices, and simply getting older.


Genetic Counseling

Cancer genetic counseling involves having a certified genetic counselor help you and your family understand your inherited cancer risk. Inherited cancer risk may be passed from parent to child. A genetic counselor explains available genetic tests and what they mean. He or she can also offer information about cancer screening, prevention, and treatment options and provide support.


Genetic counselors are trained to advise you about:

  • Your risk of developing specific types of cancer based on your family history

  • Genetic tests that can give you more information about your risk of certain types of cancer

  • The testing process and the limitations and accuracy of genetic tests

  • Emotional, psychological, and social consequences of knowing the test results

  • Cancer screening, monitoring options and cancer prevention

  • Diagnostic and treatment options

  • The privacy of your genetic information

  • Talking with family members about cancer risk


If you have any of the following, you might consider genetic testing:

· Several first-degree relatives (mother, father, sisters, brothers, children) with cancer

· Many relatives on one side of the family who have had the same type of cancer

· A cluster of cancers in your family that are known to be linked to a single gene mutation ( such as breast, ovarian, and pancreatic cancers in your family)

· A family member with more than 1 type of cancer 

· Family members who had cancer at a younger age than normal for that type of cancer

· Close relatives with cancers that are linked to rare hereditary cancer syndromes

· A family member with a rare cancer, such as breast cancer in a male or retinoblastoma

· Ethnicity (for example, Jewish ancestry is linked to ovarian and breast cancers)

· A physical finding that’s linked to an inherited cancer (such as having many colon polyps)

· A known genetic mutation in family members who have already had genetic testing


A positive result may also lead your health care provider to have you:

  • Start cancer screening tests earlier (if available for the cancer type)

  • Get screened for that type of cancer more often

  • Watch yourself closely for signs or symptoms of that kind of cancer

  • Learn about options to help reduce the risk of certain types of cancer, such as drugs or surgery


If this happens and you want to reduce your risk of cancer there are things you can do, such as

  • Eating a healthy well balanced diet

  • Not smoking

  • Exercising regularly

  • Keeping to a healthy weight

  • Staying safe in the sun


If you do develop cancer, finding it early (when the cancer is small) often means that treatment is more likely to be helpful, and easier to treat.


Timing of Test

If you do decide to go ahead with testing, choose a time when complicating factors from the outside are at a minimum. Divorce, break-ups, stressful times at work, etc. are difficult times to undergo testing. It is a good idea to plan what you will do the day you receive your results as you may feel emotional, whatever the outcome.


Making a decision about whether to have gene testing can be difficult. It’s important to find out how useful testing may be for you beforeyou do it. Thinking about the possibility of getting cancer is difficult. Talk to your health care provider and plan to meet with a genetic counselor before the actual test. This will help you know what to expect. The counselor can tell you about the pros and cons of the test, what the results might mean, and what your options are.



References

American Society of Clinical Oncology. Understanding Cancer Risk. Cancer.Net. March 2018. https://www.cancer.net/navigating-cancer-care/prevention-and-healthy-living/understanding-cancer-risk

American Society of Clinical Oncology. What to Expect When Meeting With a Genetic Counselor. Cancer.Net. April 2018.

Campbell D. Cancer : Almost half of cancer patients diagnosed too late. The Guardian. September 2014.

Cancer Research UK. Genetic Testing for Cancer Risk.2015.

Eurogentest. Predictive Testing. 2009.

Jen MY, Gossman WG. Predictive Medicine.NCBI. June 2017.

MarzuilloC, De VitoC, D’AndreaE, RossoA, VillariP. Predictive Genetic Testing for Complex Diseases: a Public Health Perspective.QJM. 107( 2); Feb 2014 : 93–97.

NHS. Predictive Genetic Tests for Cancer Risk Genes. 2015.

The American Cancer Society Medical and Editorial Content Team. Lifetime Risk of Developing or Dying From Cancer. January 2018. https://www.cancer.org/cancer/cancer-basics/lifetime-probability-of-developing-or-dying-from-cancer.html

The American Cancer Society Medical and Editorial Content team. Should I Get Genetic Testing for Cancer Risk?. 2016.

The American Cancer Society Medical and Editorial Content Team. Understanding Genetic Testing for Cancer. April 2017. https://www.cancer.org/cancer/cancer-causes/genetics/understanding-genetic-testing-for-cancer.html

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