Previous studies show a connection between physical activity and the risk of breast cancer. However, the link between this condition and sedentary time is not fully understood.
Recently, scientists from Australia have discovered that more physical activity may help lower the risk of breast cancer.
The findings were published in the British Journal of Sports Medicine.
In this research, there were nearly 131,000 women of European ancestry. Around 70,000 of them were diagnosed with invasive breast cancer, while the others did not have this condition and served as controls.
Scientists applied a statistical approach called Mendelian randomization to evaluate the link between genetic components associated with a sedentary lifestyle and physical activity, as well as cancer type and risk.
They learned that more physical activity was associated with up to 40 percent reduced risk of breast cancer, regardless of grade, stage, tumor type, or menopausal status.
Another finding was that genetic variants predisposed participants to more sedentary time and were associated with more than 100 percent higher risk of cancer.
Nevertheless, it is worth noting that the link between the increased risk of breast cancer and a sedentary lifestyle was weak overall.
To explain this association, the authors believe that low sitting time and more physical activity would help reduce fatty tissue or adiposity in the body. This may have positive effects on overall levels of sex hormones, reduced inflammation, and better metabolic function.
The main effect of physical activity on the overall risk of breast cancer is reducing the levels of androgens and estrogens, which are major risk factors for the condition.
The role of sedentary time is more controversial in previous studies. However, this research indicates that an extended period of sitting may increase the overall risk of breast cancer.
Overall, the findings suggest that people should reduce their sedentary time and increase physical activity to reduce the risk of breast cancer.
There are several limitations to this study. It used genetic factors to evaluate a small part of the variation in physical activity levels. The authors noted that only a tiny number of genes associated with a sedentary lifestyle and physical activity were included. There are probably many more that need to be examined.
Another problem is that the research reported mathematical associations. More studies should be done to learn more about the underlying mechanisms and links between the overall risk of breast cancer and genetic factors.