Debunking breast cancer myths: the truth about genes, gender, and destiny


An excerpt from Breasts: The Owner’s Manual: Every Woman’s Guide to Reducing Cancer Risk, Making Treatment Choices, and Optimizing Outcomes.

Genetics play a less important role than you probably think. Consider this fact: the identical twin sister of a woman with breast cancer has only a 20 percent chance of getting breast cancer one day—which, by the way, is the same risk as anyone with an affected sister.1 Since these twins share the exact same DNA, if genetics called all the cancer shots, risk should approach 100 percent—but it doesn’t, because genes aren’t the be-all end-all many people think they are.

Patient after patient tells me that there isn’t any breast cancer in her family, so she’s not really at risk. Yet 87 percent of women diagnosed with breast cancer do not have a single first-degree relative with breast cancer. In fact, only 5 to 10 percent of breast cancers currently prove to be hereditary, meaning that they occur because abnormal gene mutations pass from parent to child.

Of course, a vitally important part of assessing your risk includes genetic screening and family history. But if we can only blame our parents’ DNA 10 percent of the time, then factors outside of inherited genetics cause breast cancer 90 percent of the time. A major goal of this book is to teach you how to proactively make daily choices that reduce nongenetic cancer risk. Why passively await a breast cancer diagnosis when you can get actively involved in deterring it?

Patients also think their mother’s family history of breast cancer matters much more than their father’s. Clearly, you are 50 percent your father’s DNA. You inherit genes from both sides—your maternal and paternal family histories count equally. Even doctors get this wrong. So when assessing familial risk, don’t just pay attention to your maternal lineage. Look at first-, second-, and third-degree relatives on both sides: parents, siblings, and your own children; grandparents, aunts/ uncles, nieces/nephews, your own grandchildren; great-grandparents, great-aunts/great-uncles, first cousins, grandnieces/grandnephews, and your own great-grandchildren. When reviewing your father’s side, look for breast and ovarian cancers hiding in the women of more distant generations. Especially when the family tree lacks ladies, pay attention to mutation-associated cancers that show up more frequently in men than breast cancer, such as early-onset colon, prostate, and pancreatic cancers.

And speaking of the guys, most think they can’t get breast cancer, but since they actually do have breast tissue, they’re susceptible too. Male breast cancer accounts for approximately 0.8 percent of all breast cancer cases, about 2,470 men annually.2 In American men, the lifetime risk of breast cancer approaches 1.3 in 100,000.3 Interestingly, stage for stage, men survive cancer at the same rates as women; however, due to a lack of awareness that male breast cancer is even a possibility, their diagnoses usually come at later stages, increasing overall mortality rates.

Another erroneous myth about breast cancer relates to age—that it only happens to older people. While certainly less common among premenopausal than postmenopausal women, breast cancer does not discriminate when it comes to age. In the United States, 19.7 percent of all breast cancers and 11 percent of all breast cancer deaths occurred in women under fifty years old (specifically, 48,080 invasive breast cancer diagnoses, 14,050 in situ cancer diagnoses, and 4,470 breast cancer deaths befall women under fifty years old).4 In fact, the median age of breast cancer in the US is sixty-two years old, which means that exactly 50 percent of breast cancers are diagnosed under age sixty-two, and 50 percent are diagnosed at or over age sixty-two. No matter what your age, cancer cells shrink at the sight of healthy living, so we can employ the anticancer strategies in this book during all decades of life.

Finally, the misunderstood stat that all women have a 1 in 8 chance of getting breast cancer is one of the most commonly quoted statistics out there. While it’s correct, truth be told, you don’t walk around every day of your life with 1 in 8 odds of getting breast cancer! If that were true, you’d probably have cancer by next month. Breast cancer risk increases as you get older. A woman’s chance of being diagnosed with breast cancer during her twenties is 1 in 1,567 (not 1 in 8); her thirties, 1 in 220; forties, 1 in 68; fifties, 1 in 43; sixties, 1 in 29; seventies, 1 in 25; finally reaching the oft-quoted 1 in 8 as a cumulative lifetime risk once she hits eighty.5 You know those pictures with a lineup of eight “woman” icons like the ones you see on a public restroom door? They sport a caption that reads, “One in eight women will develop breast cancer in her lifetime.” Really, the icons should not be youthful triangles. We need a few canes and wheelchairs in there to more accurately reflect risk as it pertains to age.

Kristi Funk is a breast cancer surgeon and author of Breasts: The Owner’s Manual: Every Woman’s Guide to Reducing Cancer Risk, Making Treatment Choices, and Optimizing OutcomesCopyright 2018. Used by permission of Thomas Nelson

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