by Jane Ehrhardt
About 30 percent of all cancer diagnoses in females are breast cancer. Of those 287,850 new cases of invasive breast cancer annually, according to the American Cancer Society, about 85 percent will survive for at least five years. That means that, right now, around 3.8 million women are breast cancer survivors in the U.S.
What many may not know is the impact of weight, diet, and exercise on the chance of recurrence of their cancer. The Chan meta-analysis in 2014 delved into 82 follow-up studies covering over 200,000 survivors and found that women who increase their BMI by one category post-diagnosis, such as overweight to obese, increase their mortality risk up to 30 percent in the higher category.
“Many gain weight because of the chemo. Also, some forms of hormonal treatment can cause weight gain,” says Wendy Demark-Wahnefried, PhD, RD, a professor of Nutrition Sciences at UAB and Associate Director of Cancer Prevention and Control at the O’Neal Comprehensive Cancer Center.
Exercise can mitigate that risk. “Researchers have found that doing more physical activity reduced the risk of dying in survivors from breast cancer by 40 percent, even if they had not exercised before diagnosis,” says Laura Q. Rogers, MD, MPH, a professor at UAB Heersink School of Medicine department of medicine.
A 2014 meta-analysis parsed out the amount of exercise to show that one, two, and three hours of brisk walking after a breast cancer diagnosis reduced the risk of dying from any cause by 13, 24, and 34 percent, respectively, and dying from breast cancer specifically by 6, 11, and 16 percent. “The take-home message is, try to do at least two to three hours per week, but even doing one hour a week is beneficial,” Rogers says.
Exercise also mitigates the high risk of mortality breast cancer survivors face from cardiovascular causes. “Survivors are more likely to die from cardiovascular disease than breast cancer,” Demark-Wahnefried says. A 2022 study in the Journal of Clinical Oncology of 13,642 women broke down the increased risk by their treatment. The highest risk of heart failure/cardiomyopathy was in survivors who received both anthracyclines and trastuzumab, though women who received radiation therapy and aromatase inhibitors were also at increased risk over women without breast cancer.
Diet can help bolster the survivor’s system against the effects of treatment. For instance, alcohol increases the activity of aromatases in the fat stores which is a suspected mechanism for breast cancer. “Aromatases produce internal sources of estrogen in post-menopausal women. We do not want high levels of estrogen, because breast cancer is a hormone-driven cancer. Anything that’s going to stimulate estrogen is not a good thing,” Demark-Wahnefried says.
Lignans also reduce estrogen in free circulation in the body. A type of plant estrogen and a fat soluble antioxidant, lignans are found in foods such as flax seeds, sesame seeds, kale, broccoli, whole grains, and legumes, including soybeans. A review of 21 studies from the German Cancer Research Center
found that postmenopausal women with high lignan intakes were 14 percent less likely to develop breast cancer. “Lignans bind to sex hormones and because breast cancer is a hormone-driven cancer, these lignans may be able to interfere with that pathway,” Demark-Wahnefried says.
Many areas of optimum care for survivors remain unclear. All agree that a healthy diet of fruits, vegetables, whole grains, and lean meat is desired, and being overweight is bad. “Lose it slowly, though, like a half pound a week, because it looks like faster weight loss may actually cause too much stress on the body, which reacts with more inflammation. That may counteract the benefits of losing weight,” Rogers says.
Weight loss does reduce fatigue and can improve physical functioning, but it is not yet clear what its impact on breast cancer survival is. “We know gaining weight is bad. We don’t know if losing weight will help. That is what the BWEL trial will answer,” Demark-Wahnefried says. The Breast Cancer Weight Loss randomized phase III trial is expected to release their findings within a year on whether weight loss in overweight and obese survivors helps prevent breast cancer from recurring.
“There’s probably not ever going to be one single nutrient or food or exercise that makes all the difference to a breast cancer survivor. There’s no magic bullet,” Rogers says. The impact is made with an overall adjustment. To that end, Rogers and Demark-Wahnefried have created a year-long study called Amplify, now accessible at AmplifyMyHealth.org, where survivors find resources, information, and support for making the lifestyle changes to hopefully live longer and feel better. As Rogers says, “Nothing can replace feeling better.”