THURSDAY, May 19, 2016 (HealthDay News) -- Most cancer deaths among white Americans could be prevented through four healthy lifestyle changes, a large new study estimates.
Researchers said that if white men in the United States refrained from smoking, maintained a healthy weight, exercised regularly and drank alcohol only moderately (if at all), about two-thirds of their deaths from cancer could be prevented.
If white women in the United States did the same, more than half of their cancer deaths could be averted, the researchers reported.
Although the study was limited to white people, experts said similar results could expected to be seen in other racial and ethnic groups.
The "simple message" is that a healthy lifestyle matters, said Dr. Mingyang Song, a research fellow at Harvard Medical School who worked on the study.
That might sound obvious, but the effects of lifestyle and environment on cancer risk has been questioned recently. Song pointed to a study published last year in the journal Science. It proposed that "bad luck" plays a big role in cancer.
The theory goes like this: Certain body tissues, such as the colon, have a high turnover rate in their population of stem cells. That leaves the tissue more vulnerable to "random mutations" that can lead to cancer. That bad luck, in turn, goes a long way toward explaining why some tissues in the human body have high cancer rates.
Some media reports at the time painted a bleak picture, according to Dr. Graham Colditz, of Washington University School of Medicine, in St. Louis.
"They implied you should just throw up your hands -- cancer is due to chance," said Colditz, who wrote an editorial published with the new study.
These latest findings, he said, back up what many past studies have shown. "It's not all luck or chance," Colditz said. "This clearly confirms that many cancers could be prevented."
The study by Song and colleagues was published online May 19 in JAMA Oncology.
The results are based on 136,000 U.S. health professionals who have been followed since the 1980s. Song's team divided them into two groups: one they considered to have a "low risk" of cancer, based on the four lifestyle factors; and a higher-risk group.
People in the low-risk group were normal-weight or mildly overweight; had never smoked; either abstained from alcohol or drank moderately (no more than one drink per day for women, or two per day for men); and got at least 2.5 hours of moderate exercise every week.
Over the years, the low-risk group had fewer cancers. If the higher-risk group had followed the same lifestyle habits, the researchers estimated, one-quarter to one-third of their cancers could have been avoided.
And close to half of their cancer deaths might have been prevented, the report indicated.
But because the study group consisted of health professionals, they actually had healthier habits than the average American, according to Song.
So the researchers used federal cancer statistics to see what could happen if all white U.S. adults met those same lifestyle standards.
The investigators estimated that roughly half of cancer diagnoses could be averted, along with 67 percent of deaths among men and 59 percent among women.
Cancers of the lungs, throat, kidneys, liver, bladder, colon and pancreas would all show significant declines, the researchers said.
The study only used data on white Americans. However, the same pattern -- if not the same numbers -- could expected to be seen in other racial and ethnic groups, according to Dr. Farhad Islami Gomeshtapeh, of the American Cancer Society.
In the end, the study's exact numbers are not what's important, since they are estimates, said Gomeshtapeh, who wasn't involved in the study.
"What matters is, this confirms the importance of environmental factors in cancer risk," he said.
And while the study focused on four important factors, there are others, Gomeshtapeh said. People can also curb their cancer risk by eating healthfully, avoiding too much sun, and being vaccinated against human papillomavirus and hepatitis B, for example.
Beyond that, Gomeshtapeh said, they can lower their risk of dying from cancer by getting the recommended screening tests.
Colditz made the same point. But he also stressed that many Americans need help in making healthy changes. People can't do much if healthy food is too expensive or there are no safe places to exercise, or help with smoking cessation is out of reach, he said.
"We need to make cancer prevention a national priority," Colditz said. "Just telling people to lead a healthy lifestyle isn't enough."
The American Cancer Society has advice on cancer prevention.