Many cancers in the U.S. could be avoided if Americans adopted healthier lifestyles, according to a new study.
People could cut back on their cancer risk by maintaining a healthy body weight, exercising, not abusing alcohol and not smoking, the study suggests. The findings challenge the results of a 2015 report in the journal Science that attributed many cancers simply to the bad luck of mutations during cell division, according to the authors of the new report in JAMA Oncology.
The study's lead author told Reuters Health that in addition to challenging the notion that most cancers can't be prevented, the researchers wanted to clarify what proportion of U.S. cancer cases can be tied to lifestyle factors.
"We want to clarify the confusion that has been created by the Science paper and to make sure the public understands the importance of lifestyle factors on cancer risk," said Dr. Mingyang Song, of the Harvard T.H. Chan School of Public Health in Boston.
Song and his colleague Dr. Edward Giovannucci used data on 135,970 people, mostly whites, to calculate how many cancer cases could be prevented if people maintained healthy lifestyles.
They defined a healthy lifestyle as not smoking, not abusing alcohol, maintaining a healthy weight and exercising. Overall, 11,731 people, or about 9 percent, fell into the healthy group, which the researchers considered low-risk. People who didn't meet the healthy criteria were considered high risk.
About 25 percent of cancers in women and 33 percent of cancers in men could be attributed to lifestyle factors, the researchers maintain. A large number of cancer-related deaths could also be tied to those factors.
When they compared the healthy group and the general white U.S. population, the results were even more dramatic with 41 percent of cancer in women and 63 percent of cancer in men being tied to lifestyle factors.
For individual types of cancers, they found that 78 to 82 percent of lung cancers, 20 to 29 percent of colon and rectal cancers, 29 to 20 percent of pancreas cancers and 27 to 32 percent of liver cancers may be tied to lifestyle factors.
About 4 percent of breast cancer cases and about 21 percent of endometrial, ovarian and prostate cancers can be tied to lifestyle factors, too, according to the authors. Song said the results should encourage people to adopt or continue to follow healthy lifestyles.
In an editorial, Dr. Graham Colditz and Siobhan Sutcliffe of Washington University School of Medicine in St. Louis agree that the new study shows cancer is preventable.
"That’s not to say there aren’t some genetic components, but if you’re not smoking your risk is substantially lower," Colditz told Reuters Health. Referring to U.S. Vice President Joe Biden's initiative to find cancer cures, Colditz said it's also important to harness this information and implement population-based strategies to prevent cancers through lifestyle factors.
"Clearly the vice president's 'moonshot' needs to really engage and take prevention as a serious strategy so we actually implement what we know," he said. "For me the challenge is to get beyond just thinking this is all an individual choice."