A recent research review suggests that regular exercise can reduce the risk of several types of cancer. Among the cancers that could be affected by exercise were breast cancer, colon cancer, and lung cancer, three of the major types of cancer in the U.S.
According to lead author Steven Moore of the U.S. National Cancer Institute, there is no upper limit to the correlation between exercise and cancer risk. The more you exercise, the more your risk decreases.
The study found a connection between exercise and risk of cancer for 13 different types of cancer, including the three previously mentioned. Other types of cancer that can be affected by exercise include leukemia, myeloma, as well as cancers of the stomach, endometrium, bladder, rectum, liver, kidney, esophagus, and neck.
The U.S. Centers for Disease Control and Prevention recommend that adults complete a minimum of 150 minutes of moderate exercise each week, or 75 minutes of vigorous activity. Moderate exercise can include playing tennis or going for a brisk walk. Vigorous exercise can include jogging, swimming, or biking. These fitness recommendations are geared towards cardiovascular health and prevention of obesity, but the researchers say these activities can also help prevent cancer.
Moore and his research team focused on voluntary exercise that people did specifically to improve their health. Moore said that half of all American adults don’t meet the recommended minimums for physical exercise.
The researchers reviewed 12 different studies involving 1.4 million adults, ranging in age from 19 to 98. They analyzed whether the participants’ self-reported exercise levels impacted the risk of 26 total cancers.
Results showed that exercise was associated with a decreased risk for 13 of the cancers. The percent risk reduction varied by cancer type, but all 13 showed a significant risk. Overall, exercise was associated with a 7 percent decrease in the risk of cancer.
The risk of esophageal cancer decreased by 42 percent, breast cancer risk decreased by 10 percent, colon cancer decreased by 16 percent, and lung cancer experienced a 26 percent decrease.
However, the nature of the study was meant to observe an association. The results do not suggest a direct causation between exercise and cancer risk, but it is possible that exercise may be a contributing factor.
The researchers aren’t sure why exercise has this positive effect on cancer risk, but they have a few hypotheses. Exercise reduces hormone levels, including estrogen, that are often linked to various forms of cancer. Physical activity can also help reduce inflammation, which results in cells being more effective at repairing damaged DNA that could cause cancer.
Though the reason why exercise may help prevent cancer is unknown, the researchers hope that exercise will be included in public health information aimed at cancer prevention.