Healthy Lifestyle May Boost Survival After Breast Cancer Diagnosis
Exercising regularly, maintaining a healthy weight, and eating a healthy diet may help women live longer after being diagnosed with breast cancer, according to an analysis done as part of the World Cancer Research Fund/American Institute for Cancer Research Continuous Update Project.
The research was published online on Oct. 24, 2022, by the International Journal of Cancer. Read “Postdiagnosis body fatness, recreational physical activity, dietary factors and breast cancer prognosis: Global Cancer Update Programme (CUP Global) summary of evidence grading.”
About the study
Much research has been done on links between lifestyle factors and breast cancer risk. For example, we know that regular exercise and maintaining a healthy weight can help reduce the risk of being diagnosed with breast cancer.
But less research has been done on how lifestyle factors may affect outcomes after someone is diagnosed with breast cancer.
In this paper, the researchers did meta-analyses on three lifestyle factors:
weight and body fat
physical activity
diet
A meta-analysis is a study that combines and analyzes the results of a number of earlier studies.
The researchers wanted to see if these three factors affected a person’s survival after a breast cancer diagnosis. They also graded the quality of the evidence in the studies.
To look at weight and body fat, the researchers reviewed 226 studies that included more than 456,000 women diagnosed with breast cancer.
Most of the studies used body mass index (BMI) to analyze if a woman’s weight was considered healthy, but some studies used waist circumference or waist-hip ratio.
The analysis found that a higher BMI after diagnosis was linked to:
a higher risk of dying from any cause
a higher risk of dying from breast cancer
a higher risk of a second primary breast cancer diagnosis
The researchers graded this evidence as strong, which means the link is unlikely to be caused by chance or bias in the study.
The results also suggested a link between higher waist circumference and higher waist-hip ratio and a higher risk of dying from any cause or from breast cancer. Still, since fewer studies used these measures, the evidence wasn’t considered as strong.
The analysis also suggested a link between a higher BMI after diagnosis and:
breast cancer recurrence
dying of heart disease
Still, the researchers graded this evidence as limited-suggestive because of limitations in the studies’ methodologies.
To look at physical activity, the researchers reviewed 23 studies that included more than 39,000 women diagnosed with breast cancer. Most of the studies looked at what the researchers considered recreational physical activity, such as walking, running, and aerobics.
The studies used metabolic equivalent of task (MET) hours to measure how much energy a person used while doing a particular activity.
One MET is the energy you spend sitting quietly. An activity with a MET value of four means you’re exerting four times the energy you would if you were sitting still. For example, walking briskly has a MET value of four. Jogging generally has a MET value of seven. If you do a MET activity with a value of four for 30 minutes, you’ve done 120 MET minutes (4 ✕ 30) or two MET hours of physical activity.
Regular exercise — 10 MET hours a week — was linked to:
a lower risk of dying from any cause
a lower risk of dying from breast cancer
The researchers graded this evidence as limited-suggestive because of limitations in the studies’ methodologies.
The analysis also suggested up to 20 MET hours of exercise a week could reduce the risk of:
dying from any cause by 48%
dying from breast cancer by 38%
Exercising more than 20 MET hours a week didn’t seem to lower the risk of death any further.
To look at diet, the researchers reviewed 108 studies that included more than 151,000 women.
The researchers could only look for links between breast cancer outcomes and:
fruits
dairy
isoflavones from soy foods
carbohydrates
proteins
fats
fiber
alcohol
vitamin D levels
Isoflavones are plant compounds that have a weak estrogen-like effect. Isoflavones are also called phytoestrogens.
There weren’t enough studies for the researchers to even look for links between breast cancer outcomes and:
vegetables
whole grains
fish
meat
supplements
dietary patterns
Overall, the researchers said the results from studies on diet and breast cancer outcomes were limited and inconsistent, so they could only reach a few conclusions:
isoflavones from soy foods seemed to reduce the risk of dying from any cause and dying from breast cancer, as well as the risk of recurrence
dietary fiber seemed to reduce the risk of dying from any cause
higher vitamin D levels seemed to reduce the risk of dying from any cause and dying from breast cancer
Again, the researchers graded this evidence as limited-suggestive.
“In conclusion,” the researchers wrote, “our systematic reviews and meta-analyses provide strong evidence that higher post-diagnosis body fatness increases mortality among breast cancer survivors and limited but suggestive evidence that higher levels of physical activity lower mortality rates. Our results encourage the development of lifestyle recommendations for breast cancer patients to avoid obesity and be physically active if able and fit with their specific medical advice.”
What this means for you
Exercising regularly is a good way to maintain a healthy weight.
Exercise is so important that it’s now considered part of breast cancer care. The American Society of Clinical Oncology (ASCO) released guidelines on exercise, diet, and weight management during breast cancer treatment in May 2022.
Exercise remains important even after you complete breast cancer treatment. A study of more than 1,500 U.S. cancer survivors found that survivors who didn’t exercise and sat most of the day were more likely to die from cancer or other causes than people who sat less and were more active.
Still, we know that if you’re recovering from breast cancer or are currently receiving treatment — and are busy with everyday life activities — finding time to exercise almost every day can seem impossible.
It makes sense to start slowly, especially if you’ve never exercised before. You may want to start by walking for 15 to 20 minutes a day and gradually increasing the amount of time you walk. Slow bike riding or gentle stretching is also a good way to start.
You may want to walk with a friend. People are more likely to stick with a routine when they exercise with someone — plus, you can socialize at the same time.
No matter how old you are, it’s never too late to get moving. And once you start, keep at it!
Learn more about exercise.
Updated on January 10, 2023