Lack of exercise, too much sitting increases breast cancer risk

Dennis Thompson HealthDay Reporter

Thursday, Sept. 8, 2022 (HealthDay News) — Sitting behind a couch or desk can increase your risk. breast cancersuggests a new genetics-led study.

Researchers report that people who are more likely to engage in physical activity based on their DNA have a 41% lower risk of invasive breast cancer.

Previous studies have also shown a link between exercise and a lower cancer risk, but “our study suggests that the strength of this relationship may be even stronger than what observational studies have suggested.” ,” said senior researcher Brigid Lynch, associate director of cancer epidemiology at the Cancer Council. Victoria, Melbourne, Australia.

“Our study also suggests that sedentary behavior may increase the risk of breast cancer,” Lynch continued. Bigger. triple negative breast cancer — a more aggressive type of breast cancer with a worse prognosis than other types. ”

For this study, Australian researchers performed advanced genetic analyzes of approximately 131,000 women worldwide, including approximately 70,000 diagnosed with invasive breast cancer.

Previous studies have identified genetic variants associated with a person’s overall constitution, which can lead to no exercise, heavy exercise, or a tendency to sit all day, the study authors said. Says.

The researchers applied these known variants to an international female sample to see if genetic propensity for physical activity and sedentary behavior influenced cancer risk.

Young women with genes for exercising three or more days a week appeared to have a 38% lower risk of breast cancer, researchers found.

On the other hand, genetically sedentary women were 77% more likely to develop hormone receptor-negative breast cancer.

“Our findings suggest that it is important to reduce overall sitting time,” Lynch said. Try it: don’t eat lunch at your desk, go for a 30-minute walk instead.”

Using genetics to determine a person’s expected level of physical activity is “somewhat controversial,” but these results suggest that exercise may be associated with cancer risk using self-reported behavior or wearable trackers. Jennifer said, consistent with previous studies that linked Ligibel, an expert with the American Society of Clinical Oncology, said:

“Whether or not this actually provides a higher level of evidence than looking at what people do with their activity and how it’s related to cancer is probably a bit of a source of debate. Farber Cancer Institute, Boston: “There is already a significant amount of research showing that sedentary behavior is a risk factor for cancer, and this validates another way of looking at the relationship.” doing.”

But genetics-driven studies like this “raise interesting scientific questions for next steps,” said Karen Knudsen, chief executive officer of the American Cancer Society.

“What about genetic mutations associated with changes in physical activity and reduced cancer risk?” Knudsen asked, “What are these variations that have been identified? How do they affect an individual’s metabolic programming? I think these are important next-step questions.”

According to Lynch and Rigibel, there are many theoretical ways that exercise could help prevent cancer.

For example, physical activity lowers levels of circulating hormones such as: estrogenwhich “increases the risk of developing breast cancer, especially in postmenopausal women,” Lynch said.

Exercise also reduces inflammation and strengthens and lowers the immune system insulin Levels and other growth factors associated with cancer, Ligibel said.

The American Cancer Society recommends that adults do 150 to 300 minutes of moderate-intensity physical activity or 75 to 150 minutes of vigorous exercise per week.

Not only does exercise prevent many types of cancer, “emerging data suggest that physical activity lowers the risk of developing progressive disease,” Knudsen said.

The study showed that just 50 minutes of moderate-intensity activity each week was associated with some improvement in cancer risk, Lynch said.

“We’ve also found benefits in engaging in vigorous activity for at least 10 minutes at a time, at least three times a week,” says Lynch.

Sources: Brigid Lynch, PhD, Associate Director, Cancer Epidemiology, Cancer Council Victoria, Melbourne, Australia; Jennifer Ligibel, MD, Oncologist, Dana-Farber Cancer Institute, Boston. Dr. Karen Knudsen, CEO of the American Cancer Society. British Journal of Sports MedicineSeptember 6, 2022

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