A large proportion of cancer cases and deaths among U.S. individuals who are white might be prevented if people quit smoking, avoided heavy drinking, maintained a BMI between 18.5 and 27.5, and got moderate weekly exercise for at least 150 minutes or vigorous exercise for at least 75 minutes, according to new studies published online by JAMA Network

Other studies have focussed the influence of diet and benefits of exercise, from specific foods to individual cancer types, though these reviews examine the broader idea of "healthy lifestyle choices" and their impact on cancer incidence.

Addressing the impact of exercise, The risk of developing seven cancer types was 20 percent (or more) lower among the most active participants (90th percentile of activity) as compared with the least active participants (10th percentile of activity) in results from researchers at the National Cancer Institute (NCI), part of the National Institutes of Health, and the American Cancer Society, published in JAMA Internal Medicine.

This new study pooled data on 1.44 million people, ages 19 to 98, from the United States and Europe, and was able to examine a broad range of cancers, including rare malignancies.

Participants were followed for a median of 11 years during which 187,000 new cases of cancer occurred.

The investigators confirmed that leisure-time physical activity, as assessed by self-reported surveys, was associated with a lower risk of colon, breast, and endometrial cancers.

They also determined that leisure-time physical activity was associated with a lower risk of 10 additional cancers, with the greatest risk reductions for oesophageal adenocarcinoma, liver cancer, cancer of the gastric cardia, kidney cancer, and myeloid leukaemia.

Myeloma and cancers of the head and neck, rectum, and bladder also showed reduced risks that were significant, but not as strong.

Risk was reduced for lung cancer, but only for current and former smokers; the reasons for this are still being studied.

"Leisure-time physical activity is known to reduce risks of heart disease and risk of death from all causes, and our study demonstrates that it is also associated with lower risks of many types of cancer," said Steven C. Moore, Ph.D., NCI. "Furthermore, our results support that these associations are broadly generalizable to different populations, including people who are overweight or obese, or those with a history of smoking. Health care professionals counselling inactive adults should promote physical activity as a component of a healthy lifestyle and cancer prevention."

Meanwhile, results in JAMA Oncology from Mingyang Song, M.D., Sc.D., of Massachusetts General Hospital, Harvard Medical School and the Harvard T.H. Chan School of Public Health, Boston, and Edward Giovannucci, M.D., Sc.D., of the Harvard T.H. Chan School of Public Health and Harvard Medical School, Boston, analysed data from two study groups of white individuals to examine the associations between a "healthy lifestyle pattern" and cancer incidence and death.

A "healthy lifestyle pattern" was defined as never or past smoking; no or moderate drinking of alcohol (one or less drink a day for women, two or less drinks a day for men); BMI of at least 18.5 but lower than 27.5; and weekly aerobic physical activity of at least 150 minutes moderate intensity or 75 minutes vigorous intensity.

Individuals who met all four criteria were considered low risk and everyone else was high risk.

The study included 89,571 women and 46,399 men; 16,531 women and 11,731 had a healthy lifestyle pattern (low-risk group) and the remaining 73,040 women and 34,608 men were high risk.

The authors calculated population-attributable risk (PAR), which can be interpreted as the proportion of cases that would not occur if all the individuals adopted the healthy lifestyle pattern of the low-risk group.

The authors suggest about 20 percent to 40 percent of cancer cases and about half of cancer deaths could potentially be prevented through modifications to adopt the healthy lifestyle pattern of the low-risk group.

The authors note that including only white individuals in their PAR estimates may not be generalizable to other ethnic groups but the factors they considered have been established as risk factors in diverse ethnic groups too.

"These findings reinforce the predominate importance of lifestyle factors in determining cancer risk.

Therefore, primary prevention should remain a priority for cancer control," the authors conclude.

Source: JAMA Internal Medicine & JAMA Oncology