The gap in cancer death rates between college graduates and those who only went to high school is widening, the American Cancer Society reported Friday.

Among men, the least educated died of cancer at rates more than 2 1/2 times that of men with college degrees, the latest data show. In the early 1990s, they died at two times the rate of most-educated men.

For women, the numbers aren't as complete but suggest a widening gap also. The data, from 2007, compared people between the ages of 25 and 64.

People with college degrees are seeing a significant drop in cancer death rates, while people who have spent less time in school are seeing more modest improvements or sometimes none at all, explained Elizabeth Ward, who oversees research done by the cancer society.

The cancer society estimates there will be nearly 1.6 million new cancer cases in the United States this year, and 571,950 deaths. It also notes that overall cancer death rates have been dropping since the early 1990s, but the decline has been greater for some groups more than others.

Experts believe that the differences have to do with education, how much people earn and where they live, among other factors. Researchers like to use education as a measuring stick because death certificates include that information.

"Just because we're measuring education doesn't mean we think education is the direct reason" for the differences among population groups, Ward said.

That said, the cancer death rate connection to education is striking.

For all types of cancer among men, there were about 56 deaths per 100,000 for those with at least 16 years of education compared to 148 deaths per 100,000 for those with no more than 12 years of school.

For women, the rate was 59 per 100,000 for the most educated, and 119 per 100,000 for the least educated.

The gap was most striking when it comes to lung cancer.

People with a high school education or less died at a rate four to five times higher than those with at least four years of college education, the new report said.

More than a third of premature cancer deaths could have been avoided if everyone had a college degree, cancer society officials estimated.

Studies have suggested that less educated people are more likely to do risky things with their health.

They are more likely to smoke, drink and overeat, leading to obesity. All those things raise the risk for various cancers.

As for survival after diagnosis, the least-educated are often poor people without good health insurance. Studies have found that people with no health insurance are more likely to be diagnosed when their cancer is advanced stage, and they are also less likely to receive standard treatment.