Two large recent studies have confirmed that improved lifestyle habits can reduce the risk of many cancers.
One-quarter to one-third of all cancer cases as well as nearly half of all cancer deaths could be prevented if all Americans met four lifestyle goals, according to a study of 136,000 nurses and other health professionals, published in JAMA Oncology. The four goals are not smoking, maintaining a healthy weight (defined by the authors as a body mass index, or BMI, of 18.5 to 27.5), limiting or avoiding alcohol, and exercising moderately at least 150 minutes a week or vigorously at least 75 minutes a week.
About one-fifth of people met all four goals. Such “low risk” women were 25 percent less likely to develop cancer and 48 percent less likely to die from it than other women. “Low risk” men were 33 percent less likely to develop cancer and 44 percent less likely to die from it. The biggest reductions were seen in lung cancer, resulting primarily from the avoidance of smoking, followed by cancers of the colon, rectum, pancreas, kidney, bladder, endometrium, and ovary. And though the healthy lifestyle was not associated with decreased incidence of breast or prostate cancer, it was associated with a reduced chance of dying from these diseases.
The Harvard researchers estimated that the anti-cancer benefits would be even greater for the broader U.S. population, who have a much worse lifestyle pattern, on average, than the people in this study. Being health professionals, the participants were likely to be more health-conscious and have easier access to cancer screening and better treatment options than the general population. The researchers also noted that the participants were mostly white, and that the magnitude of the benefits may vary for different ethnic groups.
Focus on physical activity
The second study found that people who are most physically active are at reduced risk for 13 of 26 major types of cancer. Published in JAMA Internal Medicine, it pooled data from 12 studies involving more than a million people and compared cancer risks for people who undertook the most leisure-time physical activity (moderate or vigorous) versus those who did the least. Reduced incidence (10 to 40 percent) was seen notably for cancers of the esophagus, liver, lung, kidney, endometrium, stomach, colon, bladder, and breast. For 11 cancers there was no association. Physical activity was linked to increased risk of malignant melanoma, however, especially in geographic regions with strong sunlight. The international team of researchers controlled for factors such as age, smoking, body weight, alcohol use, and diet.
“These findings support promoting physical activity as a key component of population-wide cancer prevention and control efforts,” they concluded.
Also see 13 Ways to Cut Cancer Risk.