A new review suggests that the risk of developing 13 different types of cancer could be cut dramatically by partaking in regular exercise.

Among those cancers on the list are some of the most deadly, including breast, colon and lung cancer. It doesn’t mean you have to be in the gym every day, as only a couple of hours of exercise per week has been shown to cut the risk of cancer, writes Dennis Thompson for CBS.

Exercise To Cut Risk Of 13 Types Of Cancer

Large review reveals exciting findings

Researchers looked at 1.4 million adults over the course of the review and found significant effects for breast, colon and lung cancer.

“Those are three of the four major cancers that affect Americans today,” said Marilie Gammon, a professor of epidemiology with the University of North Carolina at Chapel Hill Gillings School of Public Health.

That is not to say that more exercise is not beneficial, as more hours in the gym correlates with a further decrease in cancer risk. Study lead author Steven Moore, an investigator with the U.S. National Cancer Institute, said that there does not appear to be an upper plateau.

“The more activity, the more the benefit,” Moore said. “As people did more, their risk continued to lower.”

Gym bunnies rejoice as exercise reduces cancer risk

Despite the fact that an association was found between exercise and decreased cancer risk, the study could not prove a cause-and-effect relationship. The other cancers affected by exercise were leukemia, myeloma and cancers of the esophagus, liver, kidney, stomach, endometrium, rectum, bladder, and head and neck.

Americans are currently advised to due 150 minutes of moderate exercise per week, or 75 minutes of vigorous exercise. Brisk walking or tennis count as moderate exercise, whereas swimming laps is an example of vigorous exercise, according to the U.S. Office of Disease Prevention and Health Promotion.

Moore and his team focused the study on exercise performed outside of work or household chores. “This is voluntary physical activity typically done to improve health,” he said.

Around 50% of American adults do not perform the minimum recommended amount of exercise, according to the study. While previous research showed a link between exercise and reduced risk of breast and colon cancer, this study is the first to encompass so many types of cancer.

Scientists impressed by results

Data from 12 U.S. and European studies was used to create a sample of 1.4 million adults aged 19-98. Scientists then examined links between self-reported exercise and cancer risk.

The reduction remained significant even after taking into account obesity and smoking history. The researchers say that more physical activity lead to a 7% reduction in cancer risk.

Esophageal cancer showed the greatest reduction, at 42%, compared to 10% for breast cancer. Colon cancer risk was reduced by 16% and lung cancer by 26%.

“This suggests that physical activity may have a role to play in population-wide cancer prevention efforts,” Moore said. The full findings of the study can be found in JAMA Internal Medicine.

It is not clear why exercise is linked to reduced cancer risk. One theory is that exercise reduces levels of hormones like estrogen that have been linked to cancer. It also helps to regulate insulate levels.

Inflammation tends to be reduced in people who partake in regular physical activity, according to Moore. There is also evidence that their cells suffer less oxidative stress and can more easily repair damaged DNA that could lead to cancer.

Gammon drew particular attention to the 42% drop in the risk of esophageal cancer. “That’s pretty amazing, because it’s a very deadly tumor,” she said. “I think the average length of survival is 11 to 12 months after you’re diagnosed.”