Genetic Testing – why should you consider genetic counselling?

Cancer in your family – what does this mean for you? You may have heard people discussing inherited cancer and the breast cancer gene, or seen in the news about Sharon Osbourne and Angelina Jolie having tests for this gene. You may have heard of the BRCA gene – how risky it is and that testing could ‘save lives’? Questions arise as to  – where can you get a test for the breast cancer gene, and if you have the gene, what would this mean for your family?

Who are genetic counsellors?

Genetic counselors are healthcare professionals with experience in understanding the role of genetics in diseases, including cancer.  They guide you through the maze of information relating to your family history, your cancer risk, hereditary risk and genetic testing options.  For this reason, genetic counseling is recommended before having any genetic test, so you can make an informed decision.

Are genetic counsellors completely necessary? 

To help answer this question, below are some common questions and answers about hereditary cancer and genetic testing, and some personal experiences of families who asked for genetic testing.

What is hereditary breast cancer* (HBC)?

Everyone has a risk of breast cancer, some more than others, and this is often linked to their family history. Of all breast cancers diagnosed about 5% are inherited. Hereditary breast cancer (HBC) means that you have an inherited predisposition to develop a particular cancer.

What is the ‘breast cancer’ gene?

Our genes define who we are and are the essence of our inheritance. Some of our genes protect us against cancer. Examples are the BRCA1 and BRCA2 genes (for ease – BRCA genes). A change (mutation) in the make-up (code) of these genes means they no longer function properly, and this increases the risk for cancer.  People born with BRCA gene mutation are said to have a HBC with a much higher risk (8x) to develop certain cancers compared to the general population. Mutations in the BRCA genes represent about 80% of families with HBC.

Why would you want to know your risk for Hereditary Breast Cancer?

The value of detecting cancer early would be a better likelihood of cure. People with HBC can have more intensive screening at a younger age. Those with a BRCA mutation can also choose to have preventative surgery.

Who should find out more about their hereditary breast cancer?

You should consider investigating the risk for HBC in your family if you have:

  • One or two close relatives with breast cancer under the age of 50 and related cancers ** or ovarian cancer under the age of 60 years;
  • A male in the family with breast cancer; 
  • More than one primary cancer in an individual; 
  • Cancer on both sides of  ‘paired’ organs – such as breasts and ovaries.

It is also important to consider one’s own diagnosis of cancer, the age of diagnosis and the type of cancer.

If you know that you’re at risk – why not just test?

Testing for HBC is complex, the results are not always clear-cut and there are implications to you and your family. A genetic counselor can help you explore this.

Where does one start?

Your genetic counselor will ask you for your family history. You should provide as much detail as possible including your own diagnosis. Assessment tools are used to answer two questions:

1) What is the chance of HBC in your family?

• And, if there is a risk for HBC, is it because of the BRCA genes?

2) What is the risk of breast cancer for you and other family members?

The answer to the first question determines if a genetic test should be done, and the second, ensures access to appropriate management regardless of genetic testing.

Does the risk for hereditary cancer only apply to breast cancer?

There are different types of hereditary cancers. Sometimes what seems to be the obvious cancer in the family is not the real picture.

Are the BRCA genes the only ones that cause hereditary breast cancer?

HBC does not only result from the BRCA genes. Your family history will be used to decide which gene should be tested.

What makes genetic testing so complex?

Genetic testing differs from most tests, as the outcome is not always definitive.  Interpretation of her genetic test is based on a combination of clinical details and the genetic test performed. There are different types of BRCA genes tests, providing varying levels of information.

A negative result from a BRCA test does not mean ‘no risk for cancer’ and a positive result does not mean a definitive diagnosis of cancer but indicates a greater risk for cancer (80%).

Genetic testing is expensive. Your genetic counselor will advise you as to which test is best suited to your family to prevent unnecessary expense.

Why do you have to know your risk to access preventative care?

People want to be able to prevent the risk of cancer occurring. The benefit of preventative surgery has only been proven in people with a BRCA mutation.

How does knowing your risk help your family?

Your genetic counselor will explore the meaning of your result for you and your family. HBC has a dominant inheritance pattern, meaning that to someone with a BRCA mutation there is a 50% chance for each of his or her children to inherit the mutation.

In a family where almost every woman in three generations had a history of breast cancer and/or had the BRCA gene mutation, they believed that their risk was not 50% but 100%.

Does knowing your result always have a good outcome?

The way people respond to their BRCA gene test result – positive or negative – is based on their personal experience.

These are just some of the issues relating to genetic testing and HBC. After reading this article, what are your thoughts about consulting a genetic counselor for genetic testing?

* Referred to as hereditary breast and ovarian cancer.  But for ease of reference and context will term it hereditary breast cancer.

** Associated cancers include ovarian, fallopian, pancreatic, prostate, melanoma and colon.

*** These case studies are based on families, but the stories have been changed to protect their identity.

Case Studies

Here are a couple of case studies to illustrate the value of genetic counseling for genetic testing.  

A 28year-old woman came for an assessment.  Her mother was diagnosed with breast cancer at age 39. Based on this history, the 28-year-old’s lifetime risk for breast cancer is double that of the general population and she can access intensive screening. With BRCA testing if she is found to have the mutation she can continue with intensive screening and consider preventative surgery, and if she is found to be negative for the mutation, she can have general screening.

A woman with colon cancer was referred for genetic testing for hereditary colon cancer.  She also had a history of ‘womb’ cancer, which was later confirmed to be ovarian cancer. This changed the risk from colon to breast cancer. She tested positive for a BRCA mutation.

A woman in her fifties, with breast cancer, was referred for BRCA testing. Her mother had breast cancer at age 41. Her maternal aunts all had cancer, as did some of her cousins. Based on the other types of cancers, the risk was no longer related to the BRCA genes but a different gene all-together. Had she just tested for BRCA, the result would have been negative and she may have thought that there is no hereditary cancer in the family.

A woman with breast cancer had BRCA testing based on her family history. She tested negative. A few years later she was shocked when the cancer recurred. Based on her family history her risk for cancer remained – regardless of her BRCA test result- based on her history.

A woman consulted with her alternative practitioner who referred her for genetic testing, as she was concerned about her family history. The test was done overseas and cost her ±R15,000. The test could have been done in South Africa for about R1,500.

Written by Noelene Kinsley.

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