CHICAGO — "In medical school, we focus on pathophysiology and mechanisms and medicines and treatments, and not so much on lifestyle" when it comes to breast cancer, said Jewel Kling, MD, from Women's Health Internal Medicine in Scottsdale, Arizona.
But when women implement a range of healthy behaviors, they can cut their risk for preventable breast cancer substantially, she told Medscape Medical News.
Kling acknowledged that framing is important, and noted that lifestyle advice can become a slippery slope.
"I don't want patients to hear me saying you caused your own cancer by not doing these things," she said. "There are a lot of things not in your control." Two of three breast cancer cases are not preventable. "But if there's one-third of cases you can focus your energy and anxiety about your health on, then you're going to feel empowered and do better."
Kling presented top cancer-prevention recommendations from the American Institute for Cancer Research (AICR) and the World Cancer Research Fund — which range from eating a healthy diet and getting regular exercise to cutting down on alcohol and red meat — here at the North American Menopause Society 2019 Annual Meeting.
The benefits of the recommendations extend beyond cancer to other chronic diseases that affect women in midlife, she noted.
"Not only is the lifestyle going to help reduce your risk of breast cancer, it's going to reduce your risk of heart disease, dementia, and a lot of other chronic health , and make you feel better at the same time," Kling reported.
Healthy Weight and Healthy Diet
The maintenance of a healthy weight is recommended because a higher percentage of body fat contributes to hyperinsulinemia, an elevated estradiol level, and inflammation, all of which increase the risk for cancer.
"These systemic factors affect a wide range of cellular and molecular processes that can subsequently promote cancer development and progression," Kling explained.
And although the data are mixed on whether a Mediterranean diet reduces the risk for breast cancer, research does suggest it decreases obesity and weight gain, which can indirectly reduce the cancer risk, she added.
In addition, cruciferous vegetables, such as broccoli, cauliflower, kale, and Brussels sprouts, are important to a healthy diet and reduce the risk for breast cancer by 15% (Breast. 2013;22:309-313). Similarly, foods with carotenoids — such as squash, carrots, spinach, kale, tomatoes, grapefruit, oranges, and apricots — reduce the risk for breast cancer by 18% to 28% (Am J Clin Nutr. 2015;101:1197-1205).
As well, the recommendations suggest avoiding or limiting fast foods, sugar-sweetened drinks, and red and processed meats.
A meta-analysis showed that the relative risk for breast cancer was 6% higher in people who consumed the most unprocessed red meat than in those who consumed the least; for processed meat, the relative risk was 9% higher (Int J Cancer. 2018;143:2787-2799).
Another study showed that postmenopausal women who consumed large amounts of processed meat had a 64% higher risk for breast cancer than postmenopausal women who consumed no processed meat (Br J Cancer. 2007;96:1139-1146).
On a positive note, though, data from the Nurses' Health Study II showed that when adolescents replaced one serving of red meat a day with poultry, fish, legumes, or nuts, risk for overall breast cancer decreased by 16% and risk for premenopausal breast cancer decreased by 24% (Int J Cancer. 2015;136:1909-1920).
Kling warned against supplements. "I think a lot of people look for the magical supplement that's going to bring those nutrients. In reality, eating a balanced, whole-food, unprocessed diet is going to give you what you need," she told Medscape Medical News.
And then there is alcohol, she said. Most people are aware that smoking can cause cancer, but fewer realize the impact of alcohol on risk.
"If we look at the breakdown of percentages, alcohol seems to have the biggest influence," she told Medscape Medical News. Alcohol is responsible for an estimated 16.4% of breast cancer cases (CA Cancer J Clin. 2018;68:446-470), and "the more you drink, the more that risk is."
Women can still enjoy an occasional drink, said Kling, but it is important that they keep in mind what constitutes a single serving of alcohol: 12 oz of a regular beer, 8 to 9 oz of a malt liquor, 5 oz of wine, or 1.5 oz of distilled spirits.
Sitting and Physical Activity
Sitting for many hours each day is an independent risk factor for many cancers, Kling said, whereas physical activity reduces insulin, estrogen, growth factors linked to cancer, and inflammation. Being active also improves body composition, quality of life, and immune-system functioning, she explained.
"Changing behaviors is very challenging," she acknowledged, but research has shown that even brief interventions — as little as 1 minute of each physician visit spent in discussion about ways to improve diet or increase physical activity — can help women make changes that reduce their risk for breast cancer.
She said she hopes that the recommendations translate into "meaningful education" and that providers make them "part of their counseling with patients."
"One of the important points is that it's an overall package. Although we focused on specific parts that will help reduce risk and are beneficial, we really want our patients to hear that a healthy lifestyle — regular exercise, a healthy diet, minimizing alcohol, not smoking" — and other behaviors taken together can have an effect of cancer risk, Kling explained.
The message about obesity is particularly important, said Karen Adams, MD, director of the Midlife Women's Clinic at Oregon Health and Science University in Portland.
"Breast cancer risk increases with 5 kg [11 pounds] of weight gain, and that increased risk isn't linear, meaning the risk skyrockets as women move from overweight to obese," she told Medscape Medical News. "Staying at a normal weight is incredibly important."
It takes time and work to lose weight, she acknowledged, but research has shown that many programs — such as Weight Watchers, Jenny Craig, Whole 30, intermittent fasting — are effective when women stick with them.
"In my own case, when I hit menopause, the things I would do to lose weight in the past still worked, but it took me so much longer that it was hard to stay motivated. Warning women about this helps them stick to it because they've been informed it will take longer," she said.
Like Kling, Adams said she wants to see women feel empowered by advice they get from their doctor.
"To me, the message to women is you have so much control over your health," she said. Many people worry about the "tiny increased risk of breast cancer" from estrogen in hormone therapy — eight extra cases per 10,000 women — when women's "risk is greater with a sedentary lifestyle, alcohol intake, or obesity than with estrogen."
She cautioned that women should not get discouraged or feel overly stressed as they try to make changes, and noted that following these recommendations does not mean eliminating all the fun.
Adams pointed out that increased physical activity can prevent one in eight cancers, and explained the importance of baby steps women can take on the path to reducing their risk.
"You don't have to train for a marathon. Don't get too ambitious at first. Just get up off the couch and walk around the block and build from there," Adams said.
"We all just do our best," she added. "We can't be perfect all the time, and when we're feasting, we should feast and enjoy it. Just don't feast every day, or even once a week."
The presentation did not involve external funding. Kling and Adams have disclosed no relevant financial relationships.
North American Menopause Society (NAMS) 2019 Annual Meeting. Presented September 27, 2019.
Medscape Medical News © 2019
Cite this: Women Can Take Charge of Certain Breast Cancer Risk Factors - Medscape - Oct 02, 2019.