5 Simple Habits That Reduce Your Risk of Breast Cancer
The disease is a killer, but as many cases are linked to causes we can control.
Fight the odds
Breast cancer is the most common cancer among European women. Even though the five-year survival rate—82 percent—has vastly improved over the past 30 years, one in eight women can still expect to be diagnosed with breast cancer. (It’s about 100 times rarer in men.) Many risk factors are out of our control: we’re more likely to develop the disease the older we get, for instance, or the taller we are, although this link may have to do with factors such as diet in childhood that contribute to height in adulthood. But current research is finding that women can, to some extent, shape their own odds.
“It’s incredibly important that people know they are not powerless,” says Susannah Brown, senior scientist at the World Cancer Research Fund (WCRF) in London, U.K. “There are steps they can take to help reduce their risk.”
Earlier this year, the WCRF partnered with the American Institute for Cancer Research to analyze more than 100 studies drawing on data from millions of women around the world. They found strong evidence of lowered breast cancer risk with simple lifestyle interventions. “It’s never too late to get healthier,” says Brown. “But the earlier you start, the better.” Here are some myths about breast cancer that you can safely ignore.
Here’s how to lower your risk.
Reduce alcohol intake
If you’re drinking for your health, think again. What you’re actually doing is raising your risk of seven different cancers, including colorectal and liver cancer. One drink a day increases your chances of developing breast cancer specifically by as much as 10 percent. Two drinks and you double it by up to 20 percent. Learn more about the link between alcohol and breast cancer.
“A lot of women are shocked by that,” says Dr. Julian Kim, a radiation oncologist with CancerCare Manitoba in Winnipeg. “They want to drink a glass of wine to relax, and they think they’re getting away scot-free.” Alcohol can increase levels of estrogen, which, like other hormones, delivers messages that control cell division in the body. Increased lifetime estrogen exposure is associated with breast cancer.
That’s why getting your first period before age 12 and reaching menopause after 55 are risk factors for the disease. Plus, when we metabolize alcohol, it’s converted into a toxic by-product called acetaldehyde, which can damage DNA and interfere with our ability to repair it.
“Even less than one drink a day raises the risk for breast cancer by 5 percent compared with non-drinkers,” says Dr. Evandro de Azambuja, Medical Director of the Breast European Adjuvant Study Team at the Institut Jules Bordet in Brussels.
Be physically active
Exercise lowers the risk of breast cancer, and being inactive increases it. The protective effects vary depending on whether or not you’re postmenopausal, whether the exercise is moderate or vigorous (gauged by whether or not you can chat comfortably while engaged in it), and how much time you devote to physical activity.
“The more you exercise, the lower your risk for breast cancer,” says Dr. Jayant Vaidya, MBBS, PhD, breast surgeon and professor of surgery and oncology at University College London. Studies show that premenopausal women who are the most active cut their risk by 17 percent.
Aim for at least 30 minutes of brisk exercise a day for prevention, but remember that any activity is better than none. “We know (exercise) also reduces the risk of at least 13 other cancers,” says Dr. Christine Friedenreich, a Calgary, Canada based epidemiologist at Alberta Health Services, who is part of a project to quantify all modifiable risk factors for all cancers across Canada. Here are more cancers that exercise can help prevent.
It’s likely there are many different ways physical activity is protective against breast cancer. Exercise decreases levels of estrogen in post-menopausal women and improves the immune system, and if you’re active outdoors, the vitamin D exposure from the sun may even make a difference. However, further research is needed to understand the impact of different kinds of activity on the body’s cells.
It can be challenging to incorporate more exercise into our hectic lives, but Shawn Chirrey, senior manager of health promotion for the Canadian Cancer Society, says that policy shifts in workplaces and municipalities can have an influence. Employers can provide discount gym memberships or find ways to increase activity levels at work. Cities can build bike lanes. “Environments can encourage people to make physical activity part of their day,” he says.
Control your weight
Being overweight or obese in later adulthood is a clear risk factor for postmenopausal breast cancer (a category that includes most cases; an estimated 83 percent of breast cancers are diagnosed after the age of 50). Putting on weight after menopause also makes you more likely to get breast cancer.
“Every 10 kilograms of postmenopausal weight gain is associated with an 18 percent relative increased risk,” notes Dr. Julian Kim at CancerCare Manitoba. (“Relative risk” means you’re 18 percent more likely to get breast cancer than someone of similar age and body type who hasn’t gained weight. Maintaining a healthy weight protects against other types of cancer as well, not to mention diabetes, heart disease, and stroke.)
“There is increasing evidence linking obesity to cancer,” says Dr. de Azmbuja. “A recent analysis of 82 studies of more than 200,000 breast cancer patients found a 75 percent increase in mortality in premenopausal women and a 34 percent increase in mortality in postmenopausal women who were obese when their cancer was diagnosed.”
As with exercise, there’s no single reason why weight influences breast cancer risk. After menopause, however, fat tissue is a key source of estrogen. Researchers have also identified links between obesity and chronic inflammation of fat tissue, which may be responsible for an elevated cancer risk in the breast. The same applies to higher levels of insulin. Whatever the reason, controlling weight, particularly after menopause, will protect you against breast cancer.
Prevention in a pill?
“Of all the big cancers—breast, lung, gastrointestinal—there’s only one that can be prevented with medications, and that’s breast cancer,” says Dr. Julian Kim at CancerCare Manitoba. Tamoxifen and raloxifene, which block estrogen receptors in breast cells, provide up to a 50 percent reduction in relative risk. Exemestane and anastrozole lower residual levels of estrogen in postmenopausal women, resulting in an up to 65 percent relative risk reduction.
This matters if your risk happens to be higher than average to begin with. In 2015, an international study of more than 67,000 women resulted in a groundbreaking new breast cancer risk calculator. Called the polygenic risk score (PRS), it takes into account what’s in your genes—not whether you carry a BRCA gene mutation— but whether a particular set of spelling mistakes in your genome is associated with greater or lower odds of developing breast cancer.
Research is ongoing, but it is important that women talk to their doctor or specialist about whether they should take medication. And if you experience any of these symptoms, make sure you talk to your doctor.
Avoid hormone replacement therapy
Hormone replacement therapy (HRT) is used to treat symptoms of menopause caused by sharply declining estrogen levels, like hot flashes, sleep disruption and vaginal dryness. It involves taking supplemental estrogen by pill or patch, sometimes in combination with another hormone, progestin. But experts estimate that HRT, which exposes postmenopausal women to increased estrogen, causes 15 percent of all new cases of breast cancer.
“Deciding whether to take HRT is a complex decision a woman needs to make with a specialist,” says Dr. Vaidya. “HRT increases the risk for breast cancer, but can also make a huge improvement in the quality of life in some women with severe menopausal symptoms. Each woman needs to carefully consider the pros and cons to make a joint decision with their doctor.”
Depending on your symptoms, your doctor may suggest local estrogen therapy, which uses low-dose vaginal estrogen, like a cream or ring, and carries a much lower risk because very little estrogen will get into your bloodstream and circulate. If you do opt for hormone replacement therapy, use it for as short a period as possible, and no more than five years. The elevated risk of breast cancer dissipates a few years after stopping HRT.
“Combined estrogen/progesterone therapy has the greatest risks when used for longer than three to five years, so if you and your doctor decide the benefits of HRT outweigh the risks, take it for no longer than this time,” says Dr. de Azambuja.
While the emerging evidence for preventing breast cancer is hopeful, putting it into practice may seem daunting. “To make healthy lifestyle changes that will last, find a way to fit them into your daily routine, and don’t try to incorporate too many at once,” advises Brown.
“If you’re overweight, dieting and exercising about eight hours a week, is enough to take off kilos,” says Dr. de Azambuja. “The weight loss will not only help you feel good, but you’ll reduce your risk for breast cancer, too.” Check out these other simple lifestyle changes you can make to reduce your risk of breast cancer.