Diagnoses Of Cancer Decline in The U.S.

Others, while agreeing that more research is needed on both prevention and treatment, hailed the development.

"We are really seeing that the investment in cancer research is really starting to pay off," said Ellen V. Sigal of Friends of Cancer Research, an advocacy group. "I think we need to do both. We need to prevent more cancer, but we still need to treat those who get cancer more effectively."

For the report, researchers analyzed data collected between 1975 and 2005 in ongoing surveys and cancer registries that federal officials use to track cancer trends. The analysis, published in today's issue of the Journal of the National Cancer Institute, found that a drop in the rate at which Americans are dying from cancer, which began in the early 1990s and has been documented in previous reports, had continued, falling about 2 percent per year for men since 2001 and 1.6 percent per year for women since 2002.

The analysis found that since 1999 the overall incidence of cancer was also falling, retreating 0.8 percent per year. Notably, the drop occurred for both men and women, although it fell much more sharply for men -- down 1.8 percent per year from 2001 to 2005, compared with 0.6 percent per year for women from 1998 through 2005. In previous years, the incidence had fluctuated for both sexes but was generally rising or stable. It was only as of 2005's data that the analysis was clear enough to know there was a long-term decline.

"This is really the first year that rates decreased in both women and men," said Ahmedin Jemal, the American Cancer Society's strategic director for cancer surveillance, who led the analysis.

The fall in lung cancer in men is the result of lower smoking rates. While fewer women are smoking, too, their incidence of lung cancer has not yet started to fall because their smoking rate declined later than men's.

Colon cancer incidence has started falling for both men and women, probably primarily the result of increased screening, which in addition to detecting early cancer also allows detection and removal of precancerous growths known as polyps.

The explanation for the drop in prostate cancer diagnoses remains less clear, but it may reflect a trend toward fewer men getting screened with a test that measures a protein in the blood called prostate-specific antigen (PSA).

The drop in breast cancer could be the result of a combination of factors, including fewer women taking hormones to alleviate hot flashes and other symptoms of menopause because of safety concerns, and fewer women getting mammograms.

"It's very difficult to say this is good news or bad news," Jemal said. "The fact that you have lower detection rates is not necessarily good news. The reduction of lung and colorectal cancer is clearly good news. But it's not so clear for breast and prostate cancer."

Critics, however, noted that many forms of cancer are still on the rise, including non-Hodgkin's lymphoma, kidney cancer and melanoma.

"If you look at the overall picture, that really distorts and reduces the realization that there's been a steady increase of non-tobacco-related cancer," said Samuel S. Epstein, a professor emeritus at the University of Illinois and the chairman of the Prevent Cancer Coalition.

Brawley agreed that more needs to be done in prevention, and he noted that the incidence rates and death rates remain higher for minorities and poor people. But he said the new report showed that rates are falling for all groups.

"If you look at the data, you can see there's something positive for black people and white people and Hispanic people. There's something positive for men. There's something positive for women. There's something positive for rich people, and there's something positive for poor people," Brawley said. "It's the first time in my career I can see positiveness for everything in the population, no matter how you slice it."