Cancer death rates are continuing their decline, researchers announced last week, and the downswing is actually picking up steam.

The new data - published in the Annual Report to the Nation produced by NCI, the Centers for Disease Control and Prevention, the American Cancer Society (ACS), and the North American Association of Central Cancer Registries - show a 2.1-percent decrease in cancer mortality rates between 2002 and 2004, an approximate doubling of the 1.1-percent decline seen each year from 1993 to 2002.

The downturn was driven by lower death rates for many of the most common cancers, including breast cancer in women, lung and prostate cancer in men, and colorectal cancer in men and women. The report's authors singled out colorectal cancer as a primary contributor to the mortality rate downturn, which they attributed to improvements in early detection and removal of polyps, while noting that improved treatments also likely played a role.

The decline, explains report co-author Dr. Brenda Edwards, who directs NCI's Surveillance Epidemiology and End Results (SEER) program from which much of the data for the Report to the Nation are drawn, "represents a convergence of a lot of factors," such as improved tobacco control policies and screening programs that have been in place for years, and incremental improvements in treatment.

"You have to orchestrate a lot of different interventions over many years to generate this type of mortality benefit," Dr. Edwards continues. "It's strong, evidence-based cancer control science and it's paying off."

Overall, the mortality rate declines from 2002 through 2004 were 2.6 percent per year among men and 1.8 percent per year among women.

The report has good news about other cancers as well, including a leveling of the incidence of lung cancer among women, which had been steadily increasing. This stabilization "is directly related to historical patterns in smoking," explains Dr. Elizabeth Ward, director of Surveillance Research at ACS. "The smoking prevalence in U.S. women declined from 33.9 percent in 1965 to 19.2 percent in 2003."

The decline in prostate cancer death rates also has been maintained, the study found, although it's unclear exactly what's driving the reduction. Although it's tempting to attribute the decline to widespread use of prostate-specific antigen (PSA) screening, the impact of screening on prostate cancer mortality is unknown, explains Dr. Howard L. Parnes, chief of the Prostate and Urologic Cancer Research Group in NCI's Division of Cancer Prevention.

"We do know that prostate cancer treatments have improved," Dr. Parnes notes, including surgery and radiation therapy for localized disease, adjuvant hormone therapy for high-risk patients undergoing radiotherapy, and taxane chemotherapy for metastatic disease, all of which have contributed to better outcomes. "We're awaiting the results of randomized clinical trials to determine the contribution of screening to the mortality statistics."

In a special section of this year's Report, the authors identified some concerning trends among American Indian and Alaska Native populations. For example, incidence rates for cancers with poor prognosis such as liver and gallbladder cancer, and common cancers such as lung, colorectal, and cervical cancer were higher in American Indian and Alaska Native populations than in non-Hispanic whites. There were substantial differences in cancer rates among American Indian and Alaska Native populations by region, with particularly high rates in Alaska and the Plains.

"The fact that lung and colorectal cancers rates were higher in some American Indian and Alaska Native populations points to the work we still have to do," said NCI Director Dr. John E. Niederhuber.

American Indians and Alaska Natives, the report found, were also much more likely to live in poverty and be obese, and less likely to have health insurance and have undergone routine cancer screenings.

By Carmen Phillips