More than 60 percent of all cancer deaths could be prevented if Americans stopped smoking, exercised more, ate healthier food and underwent recommended cancer screenings, the American Cancer Society reported.

Americans could realistically cut the death rate in half, the report says. This year 1.368 million Americans will learn they have cancer and 563,700 will die of it.

"The American Cancer Society estimates that in 2005, more than 168,140 cancer deaths will be caused by tobacco use alone," the organization said in a statement.

"In addition, scientists estimate that approximately one third (190,090) of the 570,280 cancer deaths expected to occur in 2005 will be related to poor nutrition, physical inactivity, overweight, obesity and other lifestyle factors."

That totals 358,230, or 62 percent, of all cancer deaths.

"The issue is how many could you actually pull off in reality and half doesn't seem like a big stretch," Dr. Michael Thun, head of epidemiology for the non-profit group, said in an interview.

"If one could eliminate tobacco use, you would eliminate about half of cancer deaths. If you could help people maintain a healthy body weight and get more physical activity, that would be another 10 percent," he added.

"Increasing colorectal screening and high quality mammography and Pap (tests for cervical cancer) would contribute another fraction. It is very plausible that one could get a 50-percent reduction."

For instance, breast cancer, which kills 40,000 women and men in the United States every year, can usually be easily treated if caught before it spreads. In February a team at Harvard Medical School calculated that if every woman aged between 50 and 79 got a mammogram every year, it would reduce deaths from breast cancer by 37 percent.

Colon cancer and prostate cancer, two other top cancer killers, are also easily detected early with proper screening.

KILLER TOBACCO

But the single easiest way to prevent cancer would be to stop all tobacco use, the report says.

"What we have learned from tobacco is that in addition to education, measures that make a huge difference are things like increasing excise taxes on cigarettes and the clean air laws that have been enacted to protect nonsmokers from secondhand smoke," Thun said.

Encouraging smokers to quit and changing social norms about smoking have also helped drive the nation's smoking rate below 25 percent, he said.

Tackling obesity will be more difficult, Thun said.

"Just from a common-sense point of view, anything which increases physical activity, makes healthy food more available, limits access (to) and marketing of unhealthy foods is likely to be a step in the right direction," Thun said.

He also said schools need to examine ways to get sugary sodas out of vending machines and find other sources of revenue that do not threaten the health of youngsters.

Thun said the report was not meant to make cancer patients feel they caused their own disease.

"This says just the opposite. The reality is things like smoking and obesity and physical inactivity are often described as voluntary but the choices we make are made in a social context," he said.

"In designing our communities and our lives, we inadvertently have made a lot of choices that work against health."