Want to lower your chance of getting cancer? All you need to do is exercise, according to a recent study.
An analysis of dozens of cancer studies in the U.S. and Europe concluded that exercise — or “leisure-time physical activity” — decreases cancer risk by 7 percent overall, NBC News reported.
The data suggested that 13 different types of cancer were affected by an average of two and a half hours of moderate weekly exercise; the effects were different according to the type.
The strongest link was seen in cancers of the esophagus, with a 42-percent dip in risk. Other encouraging decreases: cancers of the liver and lung, roughly 27 percent; 20 percent for leukemia; and 10 percent for breast cancer, US News and World Report added.
The findings led the study authors to conclude that doctors should prescribe exercise to patients, especially considering the fact that half of Americans get the minimum recommended amount.
“These findings support promoting physical activity as a key component of population-wide cancer-prevention and -control efforts.”
In a commentary written as a complement to the study, Marilie Gammon and colleagues said that the study findings stress the important role of exercise as a potential strategy to lessen the chance of getting the disease and to “decrease the cancer burden.”
The study examined data from 1.4 million people who participated in 12 separate studies in the U.S. and Europe between 1987 and 2004; they were followed for 11 years, Live Science explained. These people self-reported how much moderate or vigorous exercise they undertook in their free time, including walking, swimming, running, strolling, and even yardwork.
During the period of the study, more than 186,000 study participants were diagnosed with cancer.
Those who reported the highest level of exercise were in the top 10 percent of all their fellow study participants; they generally got about an hour of physical activity a day, like brisk walking. These folks were compared to people in the lowest 10 percent of their groups, or the people who exercised the least.
Comparing the top 10 percent to the lower, researchers found that people who got the most exercise reduced their risk of being diagnosed with 13 different types of cancer, including the following (the percentage the risk was lowered is in parenthesis): lung (26); kidney (23); stomach (22); endometrial (21); myeloid leukemia (20); myeloma (17); colon (16); head and neck (15); rectal (13); bladder (13); breast (10).
Exercise is already known to reduce the risk of heart disease and death from all causes, but researchers wanted to see how it affected cancer risk and found the evidence they were looking for, said Steven Moore of the National Cancer Institute, which led the study.
“(Exercise) can help people reduce their risk of heart disease. It can reduce the risk of diabetes. It extends life expectancy. And now it appears that it may reduce the risks of some cancers.”
The study found that even among obese people — and obesity is a risk factor for cancer — exercise protected them. The people who participated in the individual studies were slightly overweight on average. The lower risk applied to the overweight or obese, and people with a history of smoking.
There are three theories for how exercise lowers cancer risk. First, it may lower levels of hormones, which can lower breast and endometrial risk. Second, it may help regulate insulin, and third, it could lower inflammation.
Whatever the reason, cancer experts say the evidence that exercise directly affects tumor growth is convincing.
Of course, as is often the case in science, there are some mitigating factors to consider. The study didn’t determine how much exercise is needed, how intense it should be, or when in life exercise should start in order to enjoy the benefits. More research is needed to answer these questions and figure out how exercise lowers cancer risk.
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