The Genetics Of Cancer: What Are BRCA Genes?

Genes are present in the DNA in every cell of our body. Studies have shown that each cell contains about 30,000 different genes and these genes control the working operation of the cells, such as how quickly it grows, how often it divides, and the lifespan of the cells. They do this by making proteins that have distinct functions and act as messengers for the cells. 

Cancer begins when genes in the cell undergo mutation, preventing protein production or causing the formation of an abnormal protein. An abnormal protein does not have the proper instructions for cell growth; as a result, they cause it to multiply uncontrollably and become cancerous.

What are BRCA genes?

BRCA (pronounced ‘braca’) is the acronym for the “BReast CAncer” genes. The BRCA genes produce the proteins needed to fix damaged DNA and prevent tumor growth. They are protective genes that determine cell growth by controlling cell division, repairing mismatched DNA, and controlling the cell’s lifespan.

It should be noted that BRCA genes are not just linked to breast tissue but also ovarian, pancreatic, colorectal tissues. 

BRCA1 and BRCA2 genes

The BRCA1 and BRCA2 genes are also called tumor suppressor genes because they keep cell growth in check. Everyone has both of these genes. But in situations where the BRCA gene mutates, cells may grow uncontrollably and form a tumor. 

Women with mutated BRCA genes may develop breast cancer or ovarian cancer. This is quite rare - around 10% of women with breast cancer have a detectable mutation¹.

Men are at risk, too; BRCA gene mutation in men may cause prostate cancer or breast cancer. They also increase the risk of pancreatic cancer, colorectal, and melanoma. 

The mutations in the BRCA genes can be passed to you by your parents. However, inheriting the genes does not automatically mean you will develop cancer. This is because you inherit two of each gene, so you have two copies of the BRCA1 and BRCA2. A mutation in one of these genes means every cell in the body would contain a mutated and a normal copy.

As long as no further mutation occurs and the other copy continues to function normally, cancer will not develop. 

People who inherit mutated or harmful variants in either of these genes also have a higher cancer risk. They are more likely to develop cancer at younger ages² than those who don’t inherit the harmful variants. About 50% of women³ with either BRCA mutation will develop breast cancer by the age of 70.

Testing for mutated BRCA genes

About one in 400 people carry the mutated BRCA1 and BRCA2 genes⁴. Fortunately, it can be identified using the BRCA gene test before cancer can develop.

Given how rare the gene mutation is, genetic screening is mainly offered to those with a family history of BRCA-associated cancer and those with a family history of cancers typical at a young age. 

Genetic testing also allows people to access valuable health information to alert them to possible cancer risks. 

Speak with your healthcare provider to learn more about the testing procedure if you are worried you may be carrying a mutated BRCA1 or BRCA2 gene.

What to expect 

If you’re considering genetic testing, you may want to undergo genetic counseling before you proceed.

Genetic counseling can help you understand how the process works, what the results mean for your health, and whether you’re suited for genetic testing. It can also help you decide on the type of genetic tests you receive based on your personal and family history. 

Usually, the BRCA gene test requires blood to be drawn from the veins in your arm and sent to the lab for DNA analysis.

Other sample types could also be used for DNA testing. In special cases where you have a family history of cancer, you might want to take a saliva DNA test instead.

Understanding the results

Your test results could be in three possible outcomes - positive, negative, and uncertain.

What does a positive result mean?

A positive test result implies signs of the BRCA gene mutation in one of the breast cancer genes. As a result, you have an increased risk of developing breast cancer than others who do not have the mutation. 

However, this result does not mean that you will definitely get cancer. Some people who inherit a mutated BRCA1 or BRCA2 gene never develop cancer.

A positive result may also have implications for future generations, including:

• Men and women who inherit a mutated BRCA1 or BRCA2 gene may pass it to their children, regardless of whether they develop cancer or not. Each child has an equal chance of possessing an inherited gene mutation.

• Blood relatives of a person with mutated BRCA1 or BRCA2 genes have an increased chance of having them, too. For instance, siblings have a 50-50 chance of having the genes. 

• In some rare situations, people test positive for mutated BRCA genes but did not inherit them from their parents. This condition is called a de novo (or new) variant. The children of someone with a de novo variant may inherit it, but the siblings of a person with it are not at risk.

The benefits of early detection of the BRCA gene can include early detection of breast cancer. Most breast cancer cases can be successfully treated when detected early, which holds true for people who have a BRCA1 or BRCA 2 mutation. It may even influence future screening of your family members. 

Your doctor might recommend surgery to remove certain organs that are likely to become cancerous, such as breast tissue, ovaries, and uterus, as this will greatly reduce the risk of cancer. Family planning is an important factor to consider when deciding if and when to have surgery. 

Other options for cancer reduction can include hormonal therapies. Annual surveillance is often some means of imaging from as early as 25 years old. 

Cancers developed from a BRCA1 mutation are likely to be triple-negative breast cancer, which can be more challenging to treat than other types. 

Triple-negative breast cancer is a unique variation of breast cancer without receptors. There are three kinds of receptors; estrogen, progesterone, and a protein called the human epidermal growth factor. 

Treating triple-negative breast cancer involves surgery: either total removal of the lump through a lumpectomy or the entire breast through a mastectomy.

What does a negative result mean?

You get a negative test result when you have no BRCA gene mutation in your DNA.

However, there may still be some level of uncertainty in the results. A result is only considered a “true negative” if there is no identifiable BRCA mutation revealed in another direct relative’s test.

A negative test does not mean that you will not get cancer in the future. You still have the same cancer risk as the general population.

What does an uncertain result mean?

An uncertain result shows you have a genetic variant that may or may not increase your cancer risk. You could have BRCA1 and BRCA2 gene mutations that could be impossible to detect with the standard gene tests. 

After your test, you should meet with your genetic counselor to interpret the results and determine the way forward. This may involve repeat testing. 

The lowdown

Researchers have found that one in eight women suffer breast cancer. However, 50-70% of women with BRCA gene mutations will develop breast cancer.

Also, it should be noted that not all breast cancer develops from mutations. Only about 5-10% of breast cancer cases result from BRCA genes mutation.

Genetic testing is the only guaranteed way to check for hereditary breast cancer mutations. Since mutated genes are inherited from either of the parents, a history of cancer in either family side indicates whether mutation may be present. 

Some of the signs that doctors look out for are:

• A family history of female breast cancer at an early age (younger than 50) 

• Two members of your immediate family (mother, daughter, sister) with breast cancer 

• Three relatives (including grandmother or aunt), regardless of age, with a history of breast cancer

• Any member of the family diagnosed with both breast and ovarian cancer

• A male relative with breast cancer

• A family history of prostate cancer or specific types of pancreatic cancer

Women with BRCA1 or BRCA2 mutations who recover from breast cancer with treatment seem to have an increased risk of developing cancer a second time. This is known as recurrence.

Genetic testing has proven beneficial to help people analyze and reduce their cancer risks. Knowing that you have mutated BRCA genes allows you to make decisions and lifestyle changes that reduce your risk of developing cancer. 

Learn more about the ways you can help reduce your breast cancer risk.