The incidence of new cancer cases has been falling in recent years in the United States, the first time such an extended decline has been documented, researchers reported Tuesday.

Cancer diagnosis rates decreased by an average of 0.8 percent each year from 1999 to 2005, the last year for which data are available, according to an annual report by the National Cancer Institute, the American Cancer Society and other scientific organizations.

Death rates from cancer continued to decline as well, a trend that began some 15 years ago, the report also noted. It was published online in The Journal of the National Cancer Institute.

“Each year that you see these steady declines it gives you more confidence that we’re moving in the right direction,” said Dr. John E. Niederhuber, director of the National Cancer Institute, who is not an author of the report. “This is not just a blip on the screen.”