Promote physical activity/less sedentary

Higher levels of physical activity and less time spent sitting are likely to lower breast cancer risk, and a study designed to strengthen the proof of causality has been published online. British Journal of Sports Medicine.

Findings were generally consistent across all types and stages of the disease, revealing Mendel’s randomized study and recommending researchers focus more on exercise as a way to prevent breast cancer. I urged you to

Mendelian randomization is a technique that uses genetic variants as a surrogate for a particular risk factor (in this case, lifetime physical activity level/sedentary behavior) in order to obtain genetic evidence supporting causality. .

Observational studies have shown that physical inactivity and sedentary behavior are associated with increased breast cancer risk, but proving that they cause breast cancer is another matter.

Therefore, the researchers used Mendelian randomization to assess whether lifelong physical activity and sedentary time are causally associated with breast cancer risk in general, and different tumor types in particular.

These included data from 130,957 women of European descent. 6667 had tumors that had not yet developed (in situ). A comparison group of 54,452 women without breast cancer.

These women were participants in 76 studies under the Breast Cancer Association Consortium (BCAC), a forum for researchers interested in genetic risk for breast cancer.

The researchers then followed previously published studies using the UK Biobank’s vast repository of data on potential genetic explanations for the overall predisposition to physical activity, vigorous physical activity, or sedentary time. used. Their own study participants who were physically active or inactive.

The researchers then estimated the overall breast cancer risk depending on whether the woman had gone through menopause. By cancer type (positive for estrogen or progesterone, or HER-2, or positive/negative for all three hormones), stage (size and extent of tumor spread), and grade (degree of tumor cell abnormality) classified.

These case-control groups consisted of 23,999 perimenopausal women with invasive breast cancer and 17,686 women without. 45,839 postmenopausal breast cancer patients and 36,766 breast cancer patients.

Overall, there were 46,528 estrogen receptor-positive tumors and 11,246 controls. 34,891 progesterone receptor-positive tumors and 16,432 controls. 6945 HER2-positive tumors and 33,214 controls. 1974 triple positive case. and 4964 triple-negative cases.

There were also 42,223 invasive ductal/lobular carcinomas, 8,795 controls, and 3,510 ductal carcinomas in situ. 17,583 stage 1 cancers, 15,992 stage 2 cancers, and 4,553 stage 3-4 cancers. 34,647 moderately abnormal cell tumors and 16,432 highly abnormal cell tumors.

Analysis of the data showed that a higher genetically predicted overall level of physical activity was associated with a 41% lower risk of invasive breast cancer. This was not significantly related to menopausal status, tumor type, stage, or grade.

Similarly, the genetically predicted three or more days of vigorous physical activity per week was associated with a 38% lower risk of breast cancer compared to self-reported inactivity. These findings were consistent across most case groups.

Finally, longer genetically predicted sedentary hours were associated with a 104% higher risk of triple-negative breast cancer. These findings were consistent across hormone-negative tumor types.

The findings did not change after considering the production by a single gene of two or more apparently unrelated effects (pleiotropy), such as smoking and being overweight.

The researchers point to reasonable evidence that there are multiple causal pathways between physical activity and breast cancer risk, including overweight/obesity, metabolic disorders, sex hormones, and inflammation. states that there is a plausible biological explanation.

“The mechanisms linking sedentary time and cancer likely overlap, at least in part, with those underpinning the physical activity relationship,” the researchers suggest.

Their findings, they say, provide “strong evidence” that increasing overall physical activity and reducing sedentary time are likely to reduce the risk of breast cancer.

And they conclude: Our study adds further evidence that such behavioral changes are likely to reduce future breast cancer incidence.

“Given the high disease burden caused by cancer, which is most common in women, there is a need for a cancer strategy that focuses on physical activity and sedentary time as modifiable cancer risk factors. .”

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