WASHINGTON (Reuters) - Cancer rates have dropped for the first time in the United States and previous declines in cancer deaths are accelerating, a report released on Tuesday showed as cancer-fighting efforts produced solid results.

Regular screening for breast and colorectal cancer, declining smoking rates and improved treatments helped lead to the improvements described in a comprehensive study of cancer in the United States by government and private health experts.

"This decline is seen in blacks, it's seen in whites, it's seen in Hispanics, it's seen in all Americans," Dr. Otis Brawley, chief medical officer for the American Cancer Society, said in a telephone interview.

However, cancer remains the number two killer of Americans, with more than half a million deaths annually, topped only by heart disease. And the report detailed worrisome regional differences in lung cancer trends tied closely to whether or not individual states are taking important steps to reduce smoking.

Overall US cancer death rates began falling in 1991 and these declines are getting steeper this decade, Brawley noted.

"But the real news here is that this is first time that we've got declines in incidence (the rate of new cases per year). We've never had incidence go down since we've been keeping records starting in the 1930s," Brawley said.

The rate of new cancer cases from 2001 to 2005 declined among men by 1.8 percent per year. New cases among women fell by 0.6 percent per year from 1998 to 2005.

While overall cancer death rates decreased by 1.5 percent per year from 1993 to 2001 among men, they declined by two percent per year from 2001 to 2005. Among women, cancer death rates fell by 0.8 percent per year from 1994 to 2002 and by a much steeper 1.6 percent per year from 2002 to 2005.

"It's very promising to see the progress we are making in our fight against cancer," US Centers for Disease Control and Prevention Director Dr. Julie Gerberding said.

The report, published in the Journal of the National Cancer Institute, detailed progress in cutting new cases of the three most common kinds of cancers among men — lung, colorectal and prostate — and the two most common types among women — breast and colorectal. It also showed a leveling off of women's lung cancer death rates.

Despite the overall downward trend, death rates for certain types of cancers rose, including esophageal cancer for men, pancreatic cancer for women and liver cancer for both sexes.

"I think it speaks to improved public health measures, improved awareness about risk factors for cancer in general and improved therapies," Dr. Louis Weiner, director of the Lombardi Comprehensive Cancer Center at Georgetown University in Washington, said in a telephone interview.

Weiner said it was probably not coincidental that this progress occurred in conjunction with a doubling in funding for the government's research-supporting National Cancer Institute from 1998 to 2003, but that funding has stagnated since.

Smoking accounts for about 30 percent of all cancer deaths, including about 87 percent of lung cancer deaths. The number of US adults who smoke has dropped below 20 percent for the first time on record last year, the Centers for Disease Control and Prevention reported earlier this month.

Lung cancer cases or deaths rose in 18 states, 16 of which are in the Midwest or South. California, the first state to put in place a broad tobacco control program, was the only state with falling lung cancer incidence and death rates in women.