10 Myths about the Breast Cancer Genes (BRCA1/BRCA2)

01Jan10

The more I look on the Internet for information on hereditary breast cancer and the BRCA genes, the more disinformation I find. I think some of the inane comments I have seen are due to a general lack of knowledge of genetics and the risks of BRCA mutations. I was pretty clueless myself just a few months ago too, before I educated myself. Now I realize that in this new age of genetic research, we really need to help get the info out to people. So I’m creating this list to hopefully dispel some of the common myths surrounding BRCA particularly for the general audience.

Myth 1: I don’t have BRCA, so I don’t have to worry about breast cancer.
First, you do have the BRCA genes. We all do (men too!). Having the gene doesn’t put you at substantially higher risk of cancer, but having a harmful mutation in one of the two BRCA genes (BRCA1 or BRCA2) does. But regardless of whether you have a BRCA mutation or not, you still have a risk of breast cancer. On average, women in North America have a 7% risk of getting breast cancer before age 70. But there are many risk factors besides BRCA that can change that number like family history, age, breast density, menstrual history, smoking, obesity, and more.

Myth 2: A BRCA mutation is just another risk factor to breast cancer like smoking. We all have a risk for cancer, so what’s the big deal about BRCA?
Having a BRCA mutation is not like other risk factors. Unlike smoking, a BRCA mutation is not under our control. It is part of one’s DNA. Moreover, smoking increases the risk of breast cancer relatively little in comparison to genetic mutations. Smoking increases a woman’s risk by about 32% (may be higher if there are other contributing factors). That’s relative risk! That means if you have an average women’s risk of breast cancer and you are a smoker than your risk of breast cancer before age 70 is still only 9%. On the other hand, mutations in the BRCA genes increases an average women’s risk of breast cancer by several hundred percent. That means a BRCA1 mutation carrier has a risk of breast cancer of up to 87% before age 70. In other words, up to 7 out of 8 of BRCA1 carriers will get breast cancer before they are 70.

Myth 3: If a women with a BRCA mutation just lives a healthy life then she doesn’t need to worry about cancer.
A BRCA mutation cannot be “fixed” or compensated for by exercise and a healthy diet. Of course, exercise and a healthy diet is good for general health and prevents one from increasing their already high risk of cancer. But it is not an antidote. The BRCA genes help fix problems in our DNA that continually occur during our lifetime. DNA problems can occur naturally (like mistakes during cellular division) or due to DNA-damaging substances (like sunlight). Having a BRCA mutation means that one of the two copies of the BRCA genes is effectively broken. If the other copy becomes damaged, then our body is much less effective at repairing DNA and this is what leads to cancer. It is impossible for us to completely avoid all the causes of DNA damage. We can do our best to avoid them, but if we are born with a disadvantage in our ability to repair DNA we will always have a higher risk of cancer.

Myth 4: BRCA mutations only increases the risk for breast cancer in women.
Women and men can carry a BRCA mutation. Men with a BRCA mutation are also at increased risk for breast cancer and have a lifetime risk up to 7%. BRCA2 mutations in men appear to confer higher risk for breast cancer than BRCA1 mutations. But mutations in the BRCA genes do not just increase the risk for breast cancer. They also substantially increase the risk for ovarian cancer in women and prostate cancer in men. BRCA1 mutations confer up to 60% risk for ovarian cancer and BRCA2 mutations up to 27%. Men with BRCA2 mutations are have up to 20% risk for prostate cancer, while BRCA1 increases risk only slightly. Moreover, the BRCA mutations have been linked to a higher risk for cancers of the stomach, pancreas, colon, head, and neck.

Myth 5: No matter what type of BRCA mutation a woman has, the risks are the same.
Not only are the risks of BRCA1 and BRCA2 are not the same, but even the position of the mutation within the gene may confer different risks. For example, many researchers believe the BRCA2 gene has a region where mutations cause significantly higher risk of ovarian cancer (known as the Ovarian Cancer Cluster Region). BRCA1 is usually considered to have a higher risk of ovarian cancer than BRCA2, but mutations in the Ovarian Cancer Cluster Region of BRCA2 may actually confer nearly as high of a risk of ovarian cancer. More importantly, researchers have found that the risk of cancer in BRCA mutation carriers is highly variable and may not be equally high for everyone. There are many genes linked with breast cancer besides BRCA1 and BRCA2 and they may be a factor in the difference of risks. This is one reason why it is important to speak with a genetic counsellor to understand your personal risk factors.

Myth 6: Doing more mammograms can prevent women from BRCA mutations from getting breast cancer.
Mammograms do not prevent cancer. They are recommended to high-risk women because they can aid in detecting cancer earlier when it is easier to treat. But the diagnosis of cancer, even early stage, still has significant short and long-term impacts on one’s life. Also mammograms still do not catch all cases of cancer and they expose women to radiation. While the radiation exposure is relatively low, mammograms have been linked to an increased risk of cancer especially for young women with BRCA mutations. MRI is an alternative screening method with no radiation risk but it can lead to more unnecessary biopsies due to false alarms. But like mammograms, an MRI is only a screening method for detecting cancer and does not prevent cancer.

Myth 7: There is nothing you can do to prevent cancer if you have a BRCA mutation.
A woman can reduce her risk of breast or ovarian cancer with chemical or surgical interventions. Drugs which block estrogen like tamoxifen are known to reduce the risk of breast cancer but may have side effects or only effective for a limited time. A mastectomy (removal of the breasts) can reduce a women’s risk of breast cancer by up to 90%, but it is a irreversible operation that has significant implications on a woman’s sense of self. An oophorectomy (removal of the ovaries) can both significantly reduce a women’s risk of ovarian cancer and breast cancer. But an oophorectomy involves a radical change to a woman’s hormonal system and loss of fertility. Without hormone replacement therapy, it will cause menopause. In short, there are definitely options for women to reduce their risk, but there is no one option that is right for everyone at every stage of their life.

Myth 8: A woman should always remove her breasts and ovaries as soon as she finds out she has a mutation.
While a mastectomy or oophorectomy significantly reduce the risk of breast and ovarian cancer, they are life-changing events. Women who are still planning to have children may wish to wait. Young women who still have a relatively low risk of cancer may choose to wait. A surgery like oophorectomy has long-term risks that may increase the earlier the surgery is done. Premature loss of estrogen is also linked with long-term side effects like overall mortality, cardiovascular disease, dementia, Parkinson’s disease, depression and anxiety, osteoporosis, and impaired sexual function. Deciding if and when to do risk-reducing surgeries is an intensely personal decision, but it is also important to talk with a doctor to understand the benefits and risks of the surgeries. For a woman who does not plan to immediately undergo surgery, there are many options to risk management.

Myth 9: BRCA mutations can skip a generation.
Inherited BRCA mutations cannot “skip a generation” by definition. BRCA mutations are autosomal dominant, meaning they passed down from parent to the child at conception. If one of the parents has a BRCA mutation, then each child will have a 50% chance of inheriting the mutation. However, since BRCA mutations affect men and women’s risk of cancer differently, some families may not see its impacts as clearly if the father passed on the mutation. Men carrying a BRCA mutation may be affected by prostate or pancreatic cancer which many people do not realize are cancers associated with BRCA.

Myth 10: If I have a family history of breast cancer, but no one tested positive for a BRCA mutation then my risk is normal.
A negative test result for a harmful mutation in the BRCA gene does not necessarily mean a person is not at higher risk of cancer. If no other family members test positive but there is still a strong family history, it may mean the family’s particular mutation has not yet been identified by researchers. Or, it could mean there are other genes besides BRCA1 or BRCA2 that have mutations contributing to a higher risk.

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3 Responses to “10 Myths about the Breast Cancer Genes (BRCA1/BRCA2)”

  1. What a great post! Thanks for enlightening everyone and dispelling some misinformation! 🙂

    Teri

  2. p.s. Thanks for adding me to your blogroll, I’ve done the same with you 😉

  3. 3 Mrs. Bono Vox

    One of the best articles I have ever read on this topic. Thank you!


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