Regular exercise is linked to a lower risk of developing certain cancers, such as those of the head, neck and the lungs, according to a new study. The researchers also found that people who were diagnosed with cancer but exercised still tended to live longer than those who didn’t exercise.
Countless studies have found that exercise can blunt the risk of many health problems, cancer included. But according to study author Lee Jones, an exercise scientist at Memorial Sloan Kettering Cancer Center, much of this research has come with caveats that make it hard to pinpoint the exact benefits of exercise for cancer. So Jones and his team sought to find a way around these shortcomings. They ultimately decided to go through data from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening study, a large and randomized trial that proactively kept track of health outcomes in over 60,000 people between the ages 55 and 74 who had no past history of cancer.
“We were fortunate to identify a really robust dataset that addresses several of the prior limitations—this enabled a robust analysis of whether exercise reduced the risk of cancer in general, and then for certain cancer types, as well as long-term survival,” Jones said.
At the start of the study, the volunteers were all asked a variety of health-related questions, including if they regularly exercised. Then researchers followed the participants for over a decade, tallying up diagnosed cases of cancer and deaths in general.
Jones and his team found that regular exercisers had a slightly reduced risk of developing cancer overall compared to non-exercisers. However, the associated lower risk was higher for head and neck, breast, and lung cancers in particular. At the same time, the team found no link between exercise and a reduced risk of other types, like colorectal and ovarian cancer, and they found a possible higher risk linked to exercise for two types of cancer, melanoma and prostate cancer. They also noticed a dose-response effect, meaning that more exercise seemed to have a more potent impact on cancer risk in either direction.
The findings, published Thursday in the journal Cancer Cell, are based on observational data, meaning they can’t prove a cause-and-effect relationship between exercise and cancer. But they do suggest a more nuanced picture of how exercise affects our chances of cancer, according to Jones, even if exercise remains a net good. The same data showed that people who exercise regularly but later developed cancer were still less likely to die of any cause by the end of the study period than those who didn’t exercise, he notes.
“Our findings support current recommendations that regular exercise is important to reduce the risk of certain forms of cancer, but may not reduce risk of all forms of cancer,” he said. “Nevertheless, the longevity benefit suggests that even if being a regular exerciser does not lower your risk of all cancers, it still associates with a survival benefit.”
Jones and his team regularly study how exercise might influence cancer risk and survival. So their work here should provide them and other scientists new leads for investigating how and why exercise can be a boon against some cancers. The team is already performing studies in both animals and humans looking at how exercise could change the biology of cells in certain organs like the breasts and colon. And they eventually hope to conduct clinical trials directly testing whether following a specific exercise regimen can lower cancer risk.
For now, though, there’s plenty of incentive to pick up or maintain an exercise habit, including as a way to potentially stave off cancer. “Overall, we feel our findings strengthen the recommendation and endorsement of exercise as an important aspect of cancer prevention,” Jones said.
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