BRCA1 and 2: The Breast Cancer Genes

Although these two genes sound similar they are not related at all. What they do share is a commonality relating to an increased risk of Breast Cancer. Mutations on both genes are related to an increased risk of breast cancer, hence the names given to the genes. The two entirely distinct genes. BRCA1, first identified in 1990, is on chromosome 17, while BRCA2, identified in 1994, is on chromosome 13.

Mutations in these two genes don’t just increase your risk of breast cancer. Mutations on both increase the risk of ovarian cancer and pancreatic cancer. A BRCA1 mutation can increase the risk of cervical, uterine, and colon cancer, while mutations on BRCA2 can increase the likelihood of stomach, gallbladder, and bile duct cancer, and melanoma.

There a really good reason for this. These genes are known as “tumor suppressors,” and when they function normally, they help to maintain cell growth at the appropriate rate. When harmful mutations are present, cells have the potential for unchecked growth, increasing your risk of breast cancer.

Do I have the BRCA 1 and 2 Genes?

Yes, everyone does as they are passed on to you by both parents, so everyone has two copies of each gene. If a harmful mutation of one of these genes is inherited from a parent, every cell in the body will possess one mutated copy of the gene and one normal copy. 

As long as the other copy continues to function normally, breast cancer will not develop, which is why not every woman with a harmful mutation gets cancer. Her risk factor is much higher, but it’s certainly not a guarantee of breast cancer. However, if the other copy of the gene is altered or mutated later in her life, cancer can occur.

The part of the body where that second mutation occurs, such as the breast or the ovary determines where the cancer will develop. Science still doesn’t know exactly what causes these secondary mutations, but it may be due to other biological or environmental risk factors.

Since the harmful mutations are inherited from either the mother or the father, family history on either side is the best indication of whether the mutation is present. Doctors will look for specific “warning signs”, including:

• Two first-degree relatives (mom, daughter, sister) with breast cancer, or if one was diagnosed at 50 or younger
• Three or more first- or second-degree relatives (including grandmother or aunt), regardless of age
• Any first-degree relative with cancer diagnosed in both breasts
• Any first or second degree relative diagnosed with both breast and ovarian cancer
• Breast cancer in a male relative

Certain ethnic groups are also at a higher risk of having these mutations, including those with Ashkenazi Jewish backgrounds, and some Scandinavian, Dutch, and Icelandic peoples. In particular, Ashkenazi Jewish people (a certain group of Central European descent) have as high as a 1 in 40 chance of possessing a harmful mutation of BRCA1 or BRCA2.

How much does my risk of cancer increase if I do have the mutation?

Recent breast cancer statistics suggest that 1 in 8 women will be diagnosed with breast cancer in their lifetime. Approximately 60 percent of women who have inherited these harmful gene mutations will develop breast cancer. That’s 3-in-5 so their is a marked increase in risk. It’s very important though to remember the following;

• Not all breast cancer is due to these genetic mutations. Not every woman with a harmful mutation gets cancer. Her risk factor is much higher, but it’s certainly not a guarantee of breast cancer.
• Scientists’ best estimates suggest that only 5 to 10 percent of breast cancers are due to the mutations of BRCA1 and BRCA2.
• Not all women with the mutation will develop breast cancer, but, more than half of them will, and many at an earlier age than the average diagnosis.

Testing For BRCA1 and 2 Mutations

Testing for these mutations is available, but can be quite expensive. Pricing usually starts at several hundred dollars and can cost as much as several thousand. Thanks to the Affordable Care Act, the tests are now guaranteed to be covered by insurance if an individual meets certain criteria in terms of family history, but those criteria are very specific and only about 2 percent of the general population will meet them.

The tests are simple blood tests that are conducted in a doctor’s office, clinic, hospital, or laboratory, and then sent to a testing company. It can take several weeks to receive the results, and genetic counseling both before and after the test is highly recommended. Learning about the presence of a mutation on the genes can be difficult, so it’s important to fully understand the implications and possible responses.

Again, a positive test result doesn’t guarantee that you will develop breast cancer, but it does mean your risk factor is approximately 3-in-5 instead of 1-in-8, so some sort of proactive response is recommended.

I’ve tested positive, what are my options?

Women who do test positive have a few options. Being proactive is especially important to ensure early detection. Increased monthly breast self-exams, clinical breast exams, and mammograms, all beginning at an earlier age are all recommended to ensure early detection.

Prophylactic surgery, which removes as much of the at-risk breast tissue as possible to reduce the chance of cancer developing in the breast can also be discussed by the doctor and patient. It isn’t a guarantee that breast cancer will never appear, but it definitely reduces the risk. Preventative drug treatments are also available, but more study is needed to determine how useful these might be..