(CNN) -- Rates of new cancer diagnoses and deaths for U.S. men and women have fallen for the first time, according to a new report from leading cancer and medical research organizations.
Smoking accounts for about 30 percent of all cancer deaths nationwide, a report says.
The annual report, published online Tuesday in the Journal of the National Cancer Institute, showed this simultaneous drop in overall cancer incidence and mortality for the first time since reporting began in 1998, the study authors said.
While overall cancer death rates have been dropping, it's only now that experts see incidence, the rate at which new cancers are diagnosed, falling along with cancer mortality for both men and women, the report said.
The incidence and mortality fell for three most common cancers among men -- lung, colorectal and prostate -- and for the two most common cancers among women -- breast and colorectal. Overall, incidence rates for all cancers dropped 0.8 percent per year from 1999 to 2005 for men and women combined, the report said.
But lung cancer incidence and mortality increased in 18 states, most in the Midwest or South. These states generally have not passed anti-smoking laws, such as banning in public places or increasing excise taxes on cigarettes, said Dr. Ahmedin Jemal, lead author of the study at the American Cancer Society's Epidemiology and Surveillance Research Department.
Cigarette smoking accounts for about 30 percent of all cancer deaths nationwide, according to a U.S. surgeon general's report cited in the study. About 80 percent of those smoking-related deaths involve lung cancer, although smoking can also lead to other kinds of cancer, the report said.
Lung cancer deaths in the U.S. for men generally have been decreasing since the 1990s, while with women the numbers are leveling off now, Jemal said. That's because women started smoking in large numbers 10 to 20 years after men did, he said. See a map of lung cancer mortality rates »
"But it is still increasing in the Southern states because there is little cessation programs in those states, because of failure of the states to implement the proven tobacco intervention strategies," he said.
Smoking prevalence is still higher in Southern states than in the Northeast or the West, and the decrease in smoking in the South is slow, he said.
California was the only state that showed decline in both lung cancer incidence and deaths in women, the study said. In 1995, California banned smoking in most workplaces, and in 1998 it became the first state to ban smoking in most bars and casinos.
In men, lung cancer death rates dropped 2.8 percent per year on average in California from 1996 to 2005, which is more than twice what states in the Midwest and South showed, the study said. In women, lung cancer death rates decreased in three states from 1996 to 2005 and increased in 13 states.
Some individual cancers showed increases in death rates across the country from 1996 to 2005, including esophageal cancer in men, pancreatic cancer for women and liver cancer for both sexes.
Death rates for all cancers combined dropped across all racial and ethnic populations for both sexes, with the exception of American Indians and Alaska Natives.
The report was compiled by the American Cancer Society, the Centers for Disease Control and Prevention, the National Cancer Institute and the North American Association of Central Cancer Registries.
The report overall is "providing a validation of not only the treatments that we have for cancer, which are improving, but also for the prevention efforts," said Dr. Therese Bevers, medical director of clinical cancer prevention at M.D. Anderson Cancer Center at the University of Texas.
There is a concern that a drop in overall cancer incidence may reflect a lack of screening, said Bevers, who was not involved with the study. For example, some women may not have access to breast cancer screening because certain facilities have closed.
But the simultaneous drop in cancer deaths suggests that prevention efforts have more to do with the decrease in incidence, Bevers said.
"We'll clearly have to watch it, but I think with what we're currently seeing, it is suggesting that we are making an impact on cancer not just by improving our treatments but also by prevention activities," she said.
To reduce cancer incidence and deaths further, Jemal called for better health care access, for more initiatives to encourage people to stop smoking and for greater investment in cancer research.
"Ensuring that all populations have timely access to needed health care and prevention measures would accelerate the reduction in death rates in the future," he said.