Lifestyle changes like quitting smoking, eating better, and getting more exercise could dramatically reduce the number of cancer cases and deaths in the United States, according to a new report by the Institute of Medicine (IOM).

Changing risky behavior could prevent 100,000 cases of cancer and 60,000 cancer deaths by the year 2015, the report said. Smoking-related cancers and colorectal cancer could be especially affected.

The American Cancer Society estimates that more than 1.3 million Americans will develop cancer in 2003, and more than 550,000 will die from it. Lung cancer is the number one cancer killer in the US, while colon cancer is the second leading cause of cancer deaths.

The report, prepared by the IOM’s National Cancer Policy Board, said there is a “growing body of evidence” proving that intervention can make a difference in people’s behavior. For example, encouraging smoking cessation programs, limiting tobacco sales, and regulating exposure to secondhand smoke can all curb smoking rates, the report said.

But there are often hurdles to overcome on the path to a healthy lifestyle.

Elizabeth Ward, PhD, director of surveillance research for the American Cancer Society, says there is increasing recognition that people’s ability to maintain a healthy lifestyle is influenced by their environment.

“It’s not just an individual choice,” she said, “it’s availability.” But, she added, people need to be sure they’re making the best choice from the options they do have.

That means taking the stairs instead of the elevator, when possible, or snacking on fruit instead of cookies.

Creating a healthy environment is important in the IOM board’s recommendations for a national cancer prevention plan, detailed in the report. The IOM is an independent panel that advises the government on health and science policy.

The board urged higher taxes on tobacco products, a prohibition on tobacco sales over the Internet, and restrictions on tobacco advertising as ways to help curb tobacco use in the US.

The board also encouraged the federal government to develop a strategy to fight obesity, which has increased dramatically in the US over the past 20 years. The Centers for Disease Control and Prevention estimates that more than 60% of US adults are overweight or obese.

The strategy, it said, should include healthy meals and physical activity opportunities for school children, support for worksite fitness programs, and community development of recreation sites like biking and walking paths and parks.

The board also recommended broader insurance coverage – both from public and private insurers -- of cancer prevention and screening programs, such as mammography, nicotine replacement therapy, and screening for colorectal and cervical cancer.

Access is one of the “overriding challenges” of cancer screening, said Robert Smith, PhD, director of cancer screening for the ACS.

“Overall, there are relatively high levels of participation in cervical and breast cancer screening, and most women are aware of the importance of regular screening for these two cancers,” Smith said. “Fewer adults get regular screening for colorectal cancer, which is one of the reasons why the ACS and CDC have active programs designed to increase awareness of the value of [this screening].”

But, he added, not all Americans who should be screened have access to screening. Doctors also need to be sure they refer their patients for screening, and patients need to follow recommended screening schedules.