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Understanding the breast cancer gene: An interview with genetic counselor Maggie Miller

When it comes to understanding cancer risks like smoking or toxic chemical exposure, most people comprehend the associated dangers of these things. But when it comes to other risk factors—like genetics—some may find the information harder to decipher.

For the last couple of years the term "breast cancer gene" has been trending, partly thanks to the openness of celebrities like Angelina Jolie and Christina Applegate who—as a result of genetic testing—have publicly shared their decisions to undergo bilateral mastectomies to reduce their ongoing cancer risks. And while their bravery has certainly helped to promote education about genetic testing, using the term "breast cancer gene" isn't quite correct, said Maggie Miller, certified genetic counselor at Providence Cancer Center in Anchorage.

There are actually a few of these so-called "breast cancer genes" but the BRCA1 and the BRCA2 genes are the ones most often tested because they more frequently cause inherited breast cancer. Normal functioning BRCA genes "are called tumor suppressors or 'spell checkers' because they look for mistakes in our DNA and flag them to get them fixed," explained Miller. It's when the BRCA genes mutate and can't do their jobs that the cancer risk goes up. These mutations are what the "breast cancer gene" test is looking for. The presence of a mutation in these genes not only signals an increased risk for developing breast cancer, it also indicates a higher chance of developing ovarian cancer in women and breast and prostate cancers in men.

Women who have tested positive for the BRCA1 or 2 gene mutations are three-to-seven times more likely to develop breast or ovarian cancers in their lifetimes than those who do not carry the gene mutations. According to the American Cancer Society, "In some families with BRCA1 mutations the lifetime risk of breast cancer is as high as 80 percent, on average this risk seems to be in the range of 55 to 65 percent. For BRCA2 mutations the risk is lower, around 45 percent."

As a genetic counselor, Miller is available to speak with patients who are considering the BRCA gene test and also with those who have already tested positive for the gene mutation and are now weighing their resulting options.

"There's a fair amount of my patients who already have cancer and are concerned about getting it again or their families getting it," said Miller of why some people opt for testing. "They are concerned that it might be hereditary and want to know if there is something genetic going on."

The BRCA1 and 2 genes were discovered in the early 1990s, and then patented and sequenced by a single lab that charged $4,000 a pop for the test, a fee that posed an economic barrier for many patients. In 2013 the United States Supreme Court invalidated most gene patents, ruling that genes could not belong to companies. Today the BRCA1 and 2 tests are widely available at much more reasonable prices, a win for women who now have an affordable option for further diagnostic testing. Some labs, said Miller, will conduct the test for as little as $375 for patients paying cash.


So who should get tested? Those whose doctors have identified an elevated family history risk (two or more family members diagnosed with breast or ovarian cancer, especially before age 45) or are Jewish of Ashkenazi (Eastern European) heritage should discuss further testing options with their doctor. Those patients who have already been diagnosed with breast or ovarian cancers may also be tested. "Maybe 5 percent of cancer patients have the mutations," said Miller, and they are now faced with the decision to remove one or both breasts and their ovaries, too, or to continue with their planned course of action.

Miller said some cancer patients who do test positive don't always take the bilateral mastectomy route, instead choosing to undergo radiation after removing a lump. These patients must commit to regular screening such as imaging by digital breast tomosynthesis and MRI, as well as regular ovarian cancer screening. Some patients diagnosed with BRCA1 or 2 mutations over the age of 35 who are done childbearing will opt to have their ovaries removed, added Miller. This preempts ongoing ovarian cancer screenings which are only able to catch 6 out of 10 cases.

"One thing to remember is that most people test negative," said Miller, continuing to explain that among those who do test positive "some get cancer at 20, 27, others never get cancer at all and live to be 96." If there's any good news associated with cancer it's that testing is improving all the time. As Miller said, "I've seen so many situations where cancers have been caught and our ability to do genetic testing is just going to keep getting better and better," allowing more prevention and better outcomes for patients of all ages.


Providence Cancer Center:


Genetic testing for breast cancer facts: http://www.breastcancer.org/symptoms/testing/genetic

For a list of breast cancer resources and support in Alaska click here.

This article first appeared in the 2015 edition of Alaska Pulse magazine. Contact Pulse editor Jamie Gonzales at jgonzales@alaskadispatch.com.