Increased physical activity reduces the risk of breast cancer, suggests an international study

Increased physical activity reduces the risk of breast cancer, suggests an international study

Increased physical activity reduces the risk of breast cancer, suggests an international study

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Increasing physical activity and reducing time spent sedentary are likely to reduce the risk of breast cancer, suggests a study of more than 100,000 women.

An international team of researchers from Australia, the UK and the US used genetic analysis to establish a causal relationship between overall activity levels and cancer risk.

The study, published in the British Journal of Sports Medicine, included data from 130,957 women, 76,505 of whom had breast cancer.

Although previous research has shown a correlation between physical activity and reduced risk of breast cancer, proving causality has been difficult.

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“There has always been some uncertainty as to whether physical activity really causes a lower rate of breast cancer or whether that relationship is confused by other factors,” said Cancer Associate Professor Brigid Lynch. Council Victoria, senior author of the study.

“For example, women who tend to be more physically active may have healthier lifestyles in other ways as well.”

Lynch said the new study “suggests that this is certainly a causal effect: physical activity reduces the risk of developing breast cancer.”

“We have seen a reduction in risk in all types of breast cancer,” she said.

The researchers used a technique known as Mendelian randomization to establish causation, which uses genetic variants as proxies for particular traits, in this case physical activity and time spent sitting or lying down.

They found that a higher level of physical activity, or general movement, was associated with a 41% reduction in the risk of invasive breast cancer.

In pre- and perimenopausal women, vigorous physical activity at least three days a week was linked to a 38% lower risk of breast cancer than no vigorous activity.

“For every 100 odd minutes [of sedentary time] per day we observed an increase in the overall risk of breast cancer by 20% and a doubling of the risk of triple negative breast cancer [which is more aggressive and difficult to treat]Lynch said.

Exercise is thought to reduce the risk of breast cancer because it decreases the amount of estrogen and androgen hormones that circulate in the bloodstream. A reduction in inflammation can also be a factor.

“There has always been a lot of focus on other health behaviors such as healthy eating, maintaining a healthy weight, reducing alcohol intake,” Lynch said. “There is an important role for physical activity in cancer prevention.”

The research drew data from the UK biobank and 76 other studies conducted within the Breast Cancer Association consortium.

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A limitation of the study was that it only included data from women of European descent.

“We can’t say for sure that these genetic tools are applicable to different racial backgrounds,” Lynch said.

But she added that large observational studies in Asia and for women of different ethnicities in the United States have found correlations between physical activity and risk reduction.

“We already recommend that physical activity be one of the things you can do to reduce your risk of breast cancer,” said associate professor Wendy Ingman of the University of Adelaide, who was not involved in the study.

Other factors associated with a reduced risk of breast cancer include minimizing alcohol intake and breastfeeding. “The longer a woman breastfeeds, the lower the risk of breast cancer,” Ingman said.

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