Does exercise lower my risk of cancer?
Regular physical activity is associated with a clearly lower risk of several cancers in large population studies. Alongside that, aim to reduce the number of hours you spend sitting during the day, and use sun protection if you do a lot of outdoor sport.
Physical activity demonstrably lowers the risk of several common cancers. In an analysis of 1.44 million adults, the most active people had a 10 to 42 percent lower risk of thirteen types of cancer compared with the least active. Breast and colorectal cancer fell at the lower end of that range; oesophageal cancer at the upper end. A dose-response analysis of 98 studies involving sixteen million people confirmed this for breast, liver, colon, stomach and lung cancer: the more movement, the lower the risk.
You do not even need to exercise intensively to benefit. In a study of nearly 85,000 people wearing a wrist accelerometer, the protective effect of steps levelled off at around 9,000 steps per day. And even replacing just one hour of sitting per day with ordinary walking was associated with a lower cancer risk. That is good news if you are not a sports enthusiast.
There is one important caveat: a high level of physical activity was associated in the same large study with a 27 percent higher risk of skin melanoma. This is presumably because active people spend more time outdoors and therefore get more sun exposure. If you do a lot of outdoor sport, good sun protection is therefore essential.
Doing a lot of sport but sitting for the rest of the day is also not enough. Prolonged sitting increases the risk of colon, uterine and lung cancer independently of how active you are. And if you also have a large waist circumference, cancer risk is highest: a high level of physical activity does not fully compensate for that.
For prostate cancer the picture is unclear. One large analysis even found a slightly elevated risk with high levels of physical activity; another found a weak protective effect. No firm conclusion can be drawn from this at present. For people who already have cancer, there is good news: being physically active after a diagnosis of breast or colorectal cancer appears to confer greater survival benefit than being active beforehand, so staying active after a diagnosis is worthwhile.
All claims are based on observational research (cohort and pooled studies, systematic reviews). Causality has therefore not been proven. The studies are large and consistent for most cancer types, but the associations may partly be explained by confounding factors.
Does sitting a lot increase my risk of cancer, even if I exercise?
Sitting a lot increases your risk of certain cancers, even if you exercise. In addition to moving regularly, try to reduce your sitting time itself, because the two only partially compensate for each other.
What can I do myself to lower my risk of cancer?
By not smoking, limiting alcohol, maintaining a healthy weight, and moving enough, you can meaningfully lower your risk of several common cancers, even if cancer runs in your family.
Which lifestyle factors reduce your cancer risk the most?
Not smoking, a healthy weight, regular exercise and little or no alcohol have the strongest and best-supported protective effect. Combining all these factors lowers cancer risk the most, even when a hereditary predisposition is present.
Does drinking less alcohol meaningfully reduce your cancer risk?
Drinking less alcohol meaningfully reduces your risk of several cancer types, although it takes years before the full effect becomes visible. Stopping sooner yields greater health gains.
Does eating less red meat lower your risk of cancer?
Eating less red meat and processed meat probably lowers your risk of colorectal cancer; the association is strongest and best supported for processed meat, so that is the first thing to cut back on.
Does being overweight increase my risk of cancer, and if so, which types?
Excess weight increases your risk of at least 13 types of cancer, including uterine, colorectal, breast and liver cancer. Losing weight reduces that risk, although it remains unclear whether all methods of weight loss are equally effective for immune defence against cancer.