The conclusions of an 11-year-old scientific study, conducted on some 32,000 women throughout the United States, show that a sedentary lifestyle drastically increases the risk of post-menopausal women developing some form of breast cancer. On the other hand, intense physical exercises have been linked to a reduced risk of developing the disease, which led investigators to believe that movement is somehow associated with the mutagen potential of various cells. 

As the study authors put it, intense activity refers to jogging, dancing, bicycle riding and tennis, as well as to hard house choirs, such as scrubbing floors, windows and vacuuming throughout the house a few times a month. By observing these behaviors, scientists at the U.S. National Institutes of Health, led by Michael F. Leitzmann, were able to determine that sports or exercises and bodily weight are not directly linked, though heavier women have been known to exhibit a higher risk of developing breast cancer. 

Leitzmann explained "Notable strengths of our study include its large sample size, prospective design, high follow-up rate, and availability of relevant known or suspected breast cancer risk factors. These features enabled us to minimize any effects from other factors apart from exercise." 

The authors also said that women who are overweight or obese have a higher incidence of breast cancer because, although they exercise as instructed by physicians, they misconstrue light exercises as intensive ones. The amount of effort they put out is, objectively speaking, lower than that exhibited by women with normal weight when performing intense and strenuous exercises. 

That's why doctors argue the importance of a healthy diet and a balanced daily exercise routine – keeping a normal weight is important for preventing the appearance of breast cancer, or all other types of cancer for that matter. As no cure for this disease is yet available, prevention remains the best method to fight it, so people should really pay attention to oncologists' words of advice before it's too late.