Too little exercise, too much sitting may increase the risk of breast cancer

By Dennis Thompson, HealthDay reporter

(health day)

Thursday, September 8, 2022 (HealthDay News) — Sitting on the sofa or behind a desk may increase your risk of injury breast cancersuggests a new study based on genetics.

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

Previous research has also shown a link between exercise and a reduced risk of cancer, but “our study suggests that the strength of the association may be stronger than observational studies suggest,” said senior author Brigid Lynch, vice president of cancer epidemiology at the Cancer Council. . Victoria, in Melbourne, Australia.

“Our study also suggests that sedentary behavior may increase the risk of breast cancer,” Lynch continued. “The increased risk is greater for receptor-negative tumors, including Triple negative breast cancer A more aggressive type of breast cancer with a worse prognosis than the other types.”

In this study, Australian researchers performed a sophisticated genetic analysis of nearly 131,000 women from around the world, including nearly 70,000 diagnosed with invasive breast cancer.

Previous research has identified genetic variants associated with a person’s general willingness to exercise at all, engage in vigorous exercise or sit all day, the study authors said.

The researchers applied these known variables to their international sample of women, to see if a genetic predilection for physical activity or sedentary behavior would influence cancer risk.

They found that younger women, whose genes typically drive them to exercise three or more days a week, had a 38% lower risk of developing breast cancer.

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

“The results of our study suggest that reducing the overall duration of sitting time is key,” Lynch said. “For women who work desk jobs, try to take walking breaks throughout the day — don’t eat lunch at your desk, go for a half-hour walk instead.”

Dr. Jennifer said using genetics to judge a person’s expected levels of physical activity is “a bit controversial,” but these findings are consistent with previous studies that have linked exercise to cancer risk using self-reported behavior or wearable trackers that monitored how much people moved. Ligibel, an expert with the American Society of Clinical Oncology.

“Whether or not this provides a higher level of evidence from actually looking at what people do in terms of their activity and how that relates to cancer, I think is probably a source of little debate,” said Ligibel, Dana’s oncologist. Farber Cancer Institute in Boston. “We already have a fair amount of research showing that sedentary behavior is a risk factor for cancer, and this confirms that using a different way of looking at the relationship.”

However, Karen Knudsen, chief executive of the American Cancer Society, said a genetics-based study like this one “raises interesting scientific questions about next steps.”

“What about those genetic modifications associated with changes in physical activity and reduced cancer risk?” “What are these differences identified? How do they affect an individual’s metabolic programming? I think these are important questions related to the next step,” Knudsen said.

There are many different theoretical ways exercise can help stave off cancer, Lynch and Lijebel said.

For example, physical activity reduces the level of circulating sex hormones estrogenwhich “increases the risk of breast cancer, especially in postmenopausal women,” Lynch said.

Exercise also prevents inflammation, boosts the immune system, and reduces Insulin Levels and other growth factors are linked to cancer, Legible said.

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

Not only does exercise protect against many different types of cancer, Knudsen noted, but “emerging data suggests that physical activity will reduce the risk of aggressive disease.”

This study showed some benefit from cancer risk with just 50 minutes of moderate activity each week, Lynch said.

“We also found benefits to engaging in vigorous activity for more than 10 minutes at a time, at least three times a week,” Lynch said.

SOURCES: Brigid Lynch, Ph.D., Deputy Chair, Cancer Epidemiology, Cancer Council Victoria, Melbourne, Australia; Jennifer Legible, MD, oncologist, Dana-Farber Cancer Institute, Boston; Karen Knudsen, Ph.D., CEO, American Cancer Society; British Journal of Sports MedicineSeptember 6, 2022

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