At least half of all cancer deaths in the United States could be prevented if Americans adopted a healthier lifestyle and made better use of available screening tests for the disease, a report from the American Cancer Society states.

The information is contained in Cancer Prevention and Early Detection Facts & Figures 2005, an annual ACS report that explores some of the risk factors for cancer that people can control and change.

The report highlights trends in tobacco use, eating habits, exercise patterns, and weight gain among adults and children. The report also discusses cancer screening and ways to help more people take advantage of these potentially life-saving tests that can often find cancer well before there are noticeable symptoms

In some areas, the report shows, the US has made progress in reducing the threat of cancer. For instance, fewer adults and children are smoking now compared to a few years ago. Tobacco use causes about 30% of all cancer deaths in the US, and about 87% of lung cancer deaths, according to the report.

Drops in smoking have been the result of many factors, including higher tobacco taxes, laws limiting smoking in public places, and anti-smoking advertising. But the report warns that many of the state programs that helped lower smoking rates have been drastically scaled back because of budget problems.

A serious and growing problem is weight gain among children and adults. An ACS study published in 2003 showed that excess weight raises the risk of dying from many types of cancer including breast cancer (in certain age groups), the most common cancer in women, and prostate cancer, the most common cancer in men.

About 35% of US adults are overweight and another 30% are considered obese. Nearly 16% of kids 6-19 are too heavy; heavy kids are more likely to become heavy adults with a higher risk of developing cancer and other serious diseases.

The obesity problem stems from a number of factors, according to the report. High-calorie foods are widely available and heavily marketed; Americans rely more than ever on cars to get around; schools have cut physical education programs; many kids favor television, video games, and computers over outdoor activities.

The report makes a number of recommendations for fighting the obesity trend. One of them is to follow ACS guidelines for nutrition and exercise. Others include encouraging restaurants to provide nutrition information so diners can make better food choices, designing communities that encourage exercise with safe sidewalks, bike lanes, and parks, and improving the quality of food served to children at school.

Lifestyle changes are only part of the cancer equation, though. The report says following screening recommendations is also crucial to reducing the risk of dying from cancer. Screening can find cancers at their earliest stages, when they are easier to treat. In the case of colon cancer, screening can even prevent the disease altogether, by finding polyps so they can be removed before they turn into cancer.

Rates of screening for breast cancer and cervical cancer are generally high, though women without insurance are much less likely to get these important tests. Colon cancer screening, however, remains low. The report says improving insurance coverage of these procedures is key to increasing their use.