Genetic Factors

Every cell in your body contains genes — units of information about hereditary characteristics passed on from one generation to the next. Researchers have identified several genes that play a role in breast cancer, among them the BRCA1 and BRCA2 genes. Some people inherit an alteration in these genes, making it more likely they will develop breast or ovarian cancer. In fact, women with inherited genetic mutations can have up to an 85% chance of developing breast cancer.

About 5% to 10% of all breast cancers are hereditary.

Estimates are that inherited genetic mutations account for about 5% to 10% of all breast cancers. These cancers tend to occur earlier than non-hereditary breast cancer and are more likely to involve both breasts. If close family members developed breast cancer, especially at an early age, you may be more likely to develop hereditary breast cancer.

These cancers are more common in some ethnic groups than in the general population. For instance, people of central and eastern European Jewish — or Ashkenazic — background have a higher incidence of hereditary breast cancers. Some people of Dutch, Icelandic, or Norwegian ancestry may also be at higher risk.

Genetic Testing

If you’re in a high-risk group, testing is available to determine whether certain genetic alterations that may lead to breast cancer have been passed down to you. Usually the family member who has breast cancer is the first to get tested to see whether the cancer is hereditary in origin. If that’s the case, other members of the family may elect to get tested as well. If they test positive but haven’t yet developed cancer, they can decide to take preventative steps to reduce their chances of developing the disease. However because testing is expensive and hereditary factors account for a relatively small percentage of cancers, testing probably doesn’t make sense for the general population.

Currently, tests can identify alterations in the BRCA1 and BRCA2 genes, but scientists continue to search for other genetic alterations that may lead to breast and other cancers.

Preventative measures

What It Means…And What It Doesn’t

If you do decide to get tested, it’s important to remember that receiving a positive result doesn’t mean you have cancer, or that you will definitely get cancer. But knowing you are at high risk can help put you in charge of your situation and let you explore your options for lowering your risk.

If you are an appropriate candidate for the tests, you’ll want to know ahead of time what course of action you might take if they confirm you’re at risk. There are a variety of preventative measures you can consider with your doctor, from making lifestyle changes to increased screening to experimental hormonal treatments. Some women who are at very high risk opt to have their breasts surgically removed — a procedure called a double mastectomy — to prevent cancer from developing. Women who take this approach may decide to have their breasts surgically reconstructed at the same time as the procedure or later.

Similarly, some women who have developed cancer in one breast may decide to have the other removed to reduce their risk of a cancer recurrence.

While a double mastectomy can significantly reduce your risk of developing breast cancer, it can’t eliminate it altogether, since not all of your breast tissue can be removed.

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