How to prevent breast cancer
Breast cancer is the most common cancer among Australian women. Even though the five-year survival rate – 91 per cent – has vastly improved over the past three decades, one in seven women can still expect to be diagnosed with breast cancer. 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 childhood diet that contribute to height in adulthood. But current research is finding that we can, to some extent, shape our 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). “There are steps they can take to help reduce their risk.” Earlier this year, WCRF partnered with the American Institute for Cancer Research to analyse 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’s how to prevent breast cancer, according to the experts.
Reduce your alcohol intake
If you’re drinking for your health, think again. What you’re doing is raising your risk of seven cancers, including liver cancer. One drink a day increases your chances of developing breast cancer specifically by as much as 10 per cent. Two drinks and you double it by up to 20 per cent.
“A lot of women are shocked by that,” says radiation oncologist, Dr Julian Kim. “They drink a glass of wine to relax, and they think they’re getting away scot-free.” Alcohol can increase levels of oestrogen, which, like other hormones, delivers messages that control cell division in the body. Increased lifetime oestrogen exposure is associated with breast cancer. That’s why getting your first period before age 12 and reaching menopause after 55 are risk factors.
Plus, when we metabolise alcohol, it’s converted into acetaldehyde, a toxic by-product that can damage DNA and interfere with our ability to repair it. “There is no safe amount women can drink without increasing their risk of breast cancer,” says Brown. “However, the women who drink the most alcohol are at the greatest risk.”
When it comes to another common vice, smoking, the news is surprising. Although smoking-related illnesses cause about one in every eight deaths in Australia and may be implicated in some breast cancers, “smoking is not as strong a risk factor for breast cancer as it is for other cancers,” notes Shawn Chirrey, senior manager of health promotion for the Canadian Cancer Society.
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, and how much time you devote to physical activity.
“There’s a dose response. The more exercise you do, the greater the benefit,” says cancer epidemiologist, Dr Christine Friedenreich. In all, about 17 per cent of breast cancer can be blamed on inactivity. Aim for at least 30 minutes of brisk exercise a day for prevention, but remember that any activity is better than none. “We know it also reduces the risk of at least 13 other cancers,” says Friedenreich, who is part of a project to quantify all modifiable risk factors for all cancers.
It’s likely there are many ways physical activity is protective against breast cancer. Exercise decreases levels of oestrogen in postmenopausal women and improves the immune system, and if you’re active outdoors, 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.