For years, scientists and doctors have sought the magic bullet for cancer. Drugs, therapies, surgeries and other medical interventions have been deployed in an attempt to cure the disease, but more recently, some doctors are beginning to think that a key to battling the disease — one we’ve all got access to — is exercise.
Exercise seems to lower the risk of developing breast cancer for those who’ve never had it and the chance of a recurrence for those who have. How exactly exercise improves your breast cancer outlook is not clear, but some researchers have postulated that it boosts the immune system naturally and can help control your weight.
[See: What Not to Say to a Breast Cancer Patient.]
Dr. Sagar Sardesai, assistant professor of medicine at the Stephanie Spielman Comprehensive Breast Cancer at the Wexner Medical Center of Ohio State University, says “we know that obesity is a known risk factor for breast cancer.” Sardesai says that “overweight” is defined by a body mass index of 25 or higher, while obese refers to a BMI of 30 or higher. BMI is a measure of weight in relation to height. Although it cannot account for variations in body type and bone structure, it’s currently the most widely used measure of metabolic health. The National Institutes of Health has an online BMI calculator you can use to determine your own BMI.
Sardesai says overweight and obese women have a higher risk of developing breast cancer, “and the risk goes up as the body weight goes up. In some studies, weight gain after breast cancer diagnosis is linked with breast cancer specific mortality.” Particularly, weight gain after menopause creates an even higher risk of developing breast cancer, he says, as the body’s hormone ratios shift.
So the connection between weight and breast cancer risk seems clear. But how exactly they go together hasn’t yet been definitively determined. “A lot of studies show links between increased estrogen circulating in the body when you’re obese producing chronic inflammation” in the body that can lead to cancer, Sardesai says. One recent study suggests that adipose tissue, or fat as it’s generally referred to, actually manufactures hormones that can alter the way your body works. “The adipocytes [fat cells] in obese women behave very differently. Adipose tissue is probably the largest endocrine organ in the body. It secretes a lot of hormones and it’s part of the metabolism and part of regulating the metabolism in the body.”
He says that in lean women, the hormones produced by the adipose tissue are in harmony with the body and the metabolism, so it’s less likely to create issues. “But as the adipose tissue grows larger, it gets angry and there’s a lot of pro-inflammation,” Sardesai says. “These inflammation markers go up.” Over time, he adds, this chronic inflammation may turn into breast cancer.
So, the theory follows that by reducing the adipose tissue (through diet and exercise) in the body, you may be able to reduce the levels of circulating hormones and resulting inflammation that could lead to and feed a tumor.
Dr. Neil Iyengar, breast medical oncologist at Memorial Sloan Kettering Cancer Center in New York, says the relationship between weight, fat and hormones is a complex system and some hormone-receptive cancers may be more susceptible to developing in obese women. But, “the biology seems to be across the board,” linking hormones, inflammation and the potential for developing breast cancer.
[See: 7 Innovations in Cancer Therapy.]
No matter how exactly it works, Sardesai says it’s clear that “physical activity is associated with better outcomes both in reducing risk of cancer and in reducing breast cancer specific mortality in women who are diagnosed with early stage disease.” Although a magic dose of exercise or a preferred type of exercise to reduce incidence of breast cancer hasn’t been determined yet, Sardesai says aerobic exercise is best, and he recommends “brisk walking, fast enough so that you’re breaking a sweat. It’s not just a stroll in the park.” He recommends aiming to hit 85 percent of your maximum heart rate for 150 minutes (two and a half hours) per week. To determine your maximum heart rate, subtract your age from 220. If you’re 50 years old, your maximum heart rate would be 170.
Iyengar says he advises his patients to “really engage in activity on a daily basis and strive for 20 to 30 minutes of uninterrupted activity that makes you sweat.” He says this consistent routine will help you stick with it, and he encourages patients to find an enjoyable activity that gets your heart rate up.
Strength training — such as lifting light weights, working with resistance bands or using weight or resistance machines at the gym — has also been shown to have a benefit, and Sardesai says ideally, you’ll incorporate two strength training sessions per week into your regimen. All this physical activity, Sardesai says, has “been shown in these studies to have a better breast cancer prognosis, and it’s been shown to reduce the risk of a new breast cancer and reduce the risk of developing breast cancer in women who haven’t been diagnosed yet.”
Sardesai says that the reduction of risk of developing breast cancer that comes with exercising for at least 150 minutes per week is on the order of about 20 percent, “which is significant. Similarly in women who have been diagnosed with breast cancer, the reduction in mortality has been shown to be about 30 to 40 percent.” He says when all factors are considered, regular physical activity can reduce breast cancer mortality by about five percent over five years, which “comes close to some drugs like tamoxifen. It’s not a minimal impact. It’s a very significant impact, and it’s completely within the patient’s control. It doesn’t have a lot of side effects and the risk reduction is very close to some of these drugs we talk about in relation to breast cancer mortality,” he says.
[See: A Tour of Mammographic Screenings During Your Life.]
As to which type of exercise is best, the jury is still out, but the Breast Cancer WEight Loss Study (BWEL Study) sponsored by the Alliance for Clinical Trials in Oncology intends to look at different types of exercise to see if there’s a difference in outcome. Meanwhile, walking is a popular and useful activity to incorporate into your daily routine. Whether outside or on a treadmill, walking at a brisk pace a few times a week may just do the trick.
If you belong to a gym, check out whether they have group classes like spinning, yoga, an organized swimming group like a Masters team or other aerobic exercise sessions. Joining a group means that other people may help hold you accountable and inquire where you are if you miss a session, which can help motivate you to exercise more regularly. These group exercise classes can have the added benefit of creating a social environment where you may connect with new friends and find unexpected support during your cancer journey.
Even if you can’t hit the recommended 150 minutes of aerobic exercise and two strength training sessions per week, a 2012 study published in the journal CANCER found that any level of physical activity, whether engaged in before or after menopause, can reduce your risk of breast cancer. When it comes to exercise, some is always better than none, so get creative, find an activity you enjoy and get moving.
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Can Exercise Help With My Breast Cancer? originally appeared on usnews.com
