Cancer killed 7.6 million people worldwide last year, and 12 million new cases of the disease were reported, but the cancer death rate in the U.S. continued to decline, researchers said.

HealthDay News reported Dec. 17 that the American Cancer Society (ACS) reported that 5.4 million cancer cases and 2.9 million cancer deaths were reported in developed nations, while 6.7 million cases and 4.7 million deaths were in poorer, developing countries.

Overall, the rate of cancer cases and deaths is rising worldwide, according to the report, Global Cancer Facts & Figures, but that's mostly because people are living longer. "There is increasing life expectancy, and cancer occurs more frequently in older age groups," said study co-author Ahmedin Jemal, director of the ACS' Cancer Occurrence Office.

However, increased smoking and fat consumption, along with decreased exercise, also play a role, especially in developing countries, Jemal said. Prostate, lung and colorectal cancers are most common among men in developed nations, while breast, colorectal, and lung cancer are most common among women. In developing countries, however, lung, stomach and liver cancer are most common among men, while breast, cervix uteri, and stomach cancer are most prevalent among women.

Researchers also found that the U.S. death rate from cancer fell 2 percent annually between 2002 and 2004, Reuters reported Oct. 15. While lung-cancer rates continued to rise among U.S. women, the rates of lung, prostate and colorectal cancer fell among men, and breast and colon cancer rates declined among women.

"The significant decline in cancer death rates demonstrates important progress in the fight against cancer that has been achieved through effective tobacco control, screening, early detection, and appropriate treatment," said Julie Gerberding, director of the U.S. Centers for Disease Control and Prevention.