Men who are physically fit in middle age have a lower risk of developing certain cancers, according to a new study in JAMA Oncology. The study found that men in their 40s and 50s who performed well on a treadmill test had a lower risk of developing lung and colorectal cancers later in life, but not prostate cancer. Those that contracted any of the three types of cancer had a lower risk of dying from cancer if they were physically fit.
Many studies have linked regular exercise to a lower cancer risk, but most rely on participants’ own reports of their activity. “There’s a lot of variation between what someone reports and what they’re actually doing,” says lead researcher Susan Lakoski, a cardiologist at the Vermont Cancer Center.
This study used an objective measure of fitness: a treadmill test at gradually increasing steepness and speed. It’s part of a long-running study by the Cooper Institute in Dallas, which has collected health information about its patients since 1970. This study examined data from nearly 14,000 white men who had a preventive health exam at the Institute between 1971 and 2009, and compared it with their Medicare data about prostate, lung, and colorectal cancer from 1999 to 2009.
A high fitness score was associated with a 55 percent lower risk of lung cancer and a 44 percent lower risk of colorectal cancer than a low fitness score. Men who were in good shape at midlife and later developed lung, colorectal, or prostate cancer also had a one-third reduction of death from cancer, and a two-thirds reduction in death from cardiovascular disease, compared with men with low fitness levels.
Christine Friedenreich, an expert in exercise and cancer at Alberta Health Services in Canada, says that the study adds to growing evidence that exercise affects not only cancer risk, but survival after a cancer diagnosis. “There’s a benefit for a number of the major cancers,” she says, including colon, breast, and endometrial cancers.
Lakoski says the study was prompted by a desire to offer patients more than a generic recommendation to stay active. Future studies should answer the question: “What is the right amount of exercise for you to prevent certain diseases?” she says. A fitness test is sometimes used to prescribe exercise for patients with certain health problems, she says, but it should also be considered for wider use to help prevent disease.