Exercise Decreases Risk Of 13 Cancers Including Leukemia And Myeloma: Study By Tyler MacDonald | May 17, 2016 10:02 AM EDT A new study suggests that even a couple hours of exercise a week can significantly reduce your risk for numerous types of cancer. The study reviewed data on 1.4 million adults and examined the connection between cancer and exercise, revealing that working out regularly reduces the risk of breast, colon and lung cancer. "Those are three of the four major cancers that affect Americans today," said Marilie Gammon, a professor of epidemiology at University of North Carolina who wrote in a commentary related to the study. In addition, the study found that the more hours of physical activity that a person conducts, the further his or her risk for cancer decreases. "The more activity, the more the benefit," said Steven Moore of the U.S. National Cancer Institute and lead author of the study. "As people did more, their risk continued to lower." Watch video The team used data from 12 U.S. and European studies, totaling 1.4 million adults between the ages of 19 and 98. Afterwards, they examined the link between physical activity and the risk of 26 cancers. The results revealed a definitive link between regular exercise and a decrease in the risk of 13 cancers. Overall, higher levels of exercise were connected with a 7 percent lower risk of total cancer, even after taking into consideration factors such as obesity and smoking history. The beneficial effects of physical activity were connected to cancers of the liver, kidney and bladder, as well as leukemia and myeloma. "This suggests that physical activity may have a role to play in population-wide cancer prevention efforts," Moore said. Despite the promise of the findings, the connection between exercise and a reduction in cancer risk is not causal, and further research will need to be conducted to determine if there is a cause-and-effect relationship. "These exciting findings by Moore et al underscore the importance of leisure-time physical activity as a potential risk reduction strategy to decrease the cancer burden in the United States and abroad," Gammon added. "However, additional research, including more formal mediation analyses, on the underlying mechanisms for the recreational physical activity-cancer association should be pursued vigorously." The findings were published May 16 in the journal JAMA Internal Medicine.