Physical activity decreases risk of seven cancers

BY W. GIFFORD- JONES MD & DIANA GIFFORD-JONES

Is physical activity good for you? During COVID times, it might be prudent to avoid cramped, indoor gyms. But outdoor activity in open spaces is invariably a healthy choice. We know that getting off the couch and out for a walk helps prevent obesity, Type 2 diabetes, and heart attacks. And good news! A recent report from the American Cancer Society says exercise also lowers the risk of seven types of cancers.

Dr. Charles Matthews of the National Cancer Institute in the U.S. pooled data from nine studies about how leisure-time activity affects fifteen types of cancer. His results should act as a huge incentive to get people of all ages moving.

Matthews and his colleagues report that those who engaged in 7.5 to 15 hours a week of physical activity showed significantly lower risk of 7 of the 15 cancers studied. The decrease became greater with more hours of activity.

For instance, moderate intensity activity was associated with 8% lower risk of colon cancer in men. Double the intensity, the benefit was 14%. Risk of breast cancer in women was reduced by 6-10% depending on the amount of exercise. For malignancy of the uterus, the difference was: 10-18%, kidney 11-17%, myeloma 14-19%, liver 18-27%, and non-Hodgkin lymphoma in women 11-18%.

But how does exercise decrease the risk of these malignancies? It’s believed that exercise decreases hormone levels that trigger some types of cancer. We also know that exercise increases the immune response, which helps to fight cancer. Some malignancies are also linked to obesity. Exercise burns up calories and decreases obesity to help lower risk.

Exercise can help to decrease the risk of these malignancies. But never forget that an active lifestyle sets you up for the physical and mental agility you want during your senior years too. Back in the 1960s, a Japanese marketing campaign proposed “10,000 steps a day”, equating to about five miles. Most North Americans walk far less – under 5,000 steps on average.

There are some skeptics, like the writer Mark Twain, who claimed he had been to the funeral of many friends who believed in exercise more than he did.

But it would be prudent for doctors to write on a prescription, “More exercise and use a pedometer.” Why count steps when we all know exercise is good for us? Research consistently shows that pedometers are great psychological motivators. They inspire us to get walking.

Dr. Paul Dudley White, Harvard’s renowned cardiologist, rode his bicycle to work and was a firm believer in stepping-it-up. He taught, “If you want to know how flabby your brain is, feel your leg muscles!” Or as the British historian George Trevelyan remarked, “I have two doctors, my left leg and my right.”

Remember that walking is free, simple and convenient. There’s also no need to try and break the record of the one-minute mile or purchase expensive exercise machines.

Unfortunately, walking five miles daily for a 150-pound person burns up only 500 calories. And it is so easy to consume 500 calories.  Just three of the wrong cookies can undo all that walking.

Exercise and watching calories have always been a tough sell to those who haven’t made it a lifetime passion. Michelle Obama got it right when she planted a vegetable garden at the White House and launched the Let’s Move initiative to help kids engage in physical activity. Starting young is ideal, but it’s never too late to start enjoying a daily walk.  And don’t let the excuse of “no time” deter you.

Heed the Earl of Darby, who advised, “Those who do not find time for exercise will have to find time for illness.”