"During this time period it became increasingly apparent that prostate cancer was an important public health problem in the African American community and there was a lot of effort to address this issue by raising awareness of screening," Li said. "I think that maybe we're seeing some of the benefits of that work here."

For the study, the researchers analyzed data from 12 population-based urban cancer registries throughout the continental U.S. and Hawaii, representing about 14 percent of the population. They focused on distant-stage cancers for which screening tests were widely available.

Data included female breast cancer cases between ages 40 and 64, male prostate cancer cases between ages 50 and 64, and male and female colorectal cancer cases between ages 50 and 64. The age ranges were chosen to reflect American Cancer Society screening guidelines and Medicare eligibility.

The study did not evaluate late-stage cancer rates among Asians/Pacific Islanders, American Indians/Alaska Natives or those of Hispanic ethnicity because of insufficient numbers of cases within each racial/ethnic group to conduct a statistically significant analysis of cancer trends over time.

Because the analysis was based on population-based data on incidence rates of advanced cancer but not on individual data that would reflect tumor biology or screening practices, the authors caution that the findings cannot predict individual risk but should be interpreted as a broad view of cancer trends over time.

"Epidemiologic studies such as this one are an important first step in understanding trends in disease rates on a population level," McDougal said. "However, we cannot draw strong conclusions regarding the factors contributing to the trends observed from this study, as its goal was to describe trends over time without using detailed data on individual cases and the complex factors that contribute to disease."

The authors concluded that blacks continue to have a disproportionately high cancer burden, and therefore "continued multipronged efforts aimed at improving access to breast, colorectal and prostate cancer prevention, screening, diagnostics and treatment services are warranted."Fred Hutchinson Cancer Research Center funded the study.

Source: Fred Hutchinson Cancer Research Center