Atlanta ? The U.S. cancer death rate fell again in 2006, a new analysis shows, continuing a slow downward trend that experts attribute to declines in smoking, earlier detection and better treatment.

About 560,000 people died of cancer that year, according to an American Cancer Society report released Wednesday. The new numbers show the death rate fell by less than 2 percent, but since that decline was better than the previous year, the cancer society applauded the progress.

Cancer is the nation’s No. 2 killer, behind heart disease, and accounts for nearly a quarter of annual deaths. The cancer death rate has been falling since the early 1990s.

The new rate shows 181 cancer deaths per 100,000 people. That was down from about 184 in 2005.