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Racial disparities in cancer death rates from lung and other smoking-related cancers have narrowed since the early 1990s, while the gap has widened for some cancers whose death rates are more closely tied to screening and treatment, according to a new study published in Cancer Epidemiology Biomarkers and Prevention (CEBP).

The study, led by John Oliver DeLancey of the American Cancer Society’s Department of Epidemiology and Surveillance Research, was based on mortality data from the National Center for Health Statistics from 1975 through 2004. DeLancey and colleagues compared the cancer death rates in whites and African Americans for all cancers combined, for lung and other smoking-related cancers (oral cavity, esophageal, pharynx, larynx, pancreas, bladder, kidney), and for 3 cancers that are more likely to be affected by screening and early treatment -– breast, colorectal, and prostate.

The researchers found that the gap in overall cancer death rates between black and white Americans narrowed from the early 1990s through 2004, but that this trend was driven predominantly by a more rapid decrease in death rates in blacks than in whites, especially among men. More research is needed into what factors might be related to this difference, the researchers say.

"This study suggests that tobacco control measures appear to be working," said DeLancey, noting that not only smoking prevalence, but the black-white differences in smoking prevalence, have decreased since the 1970s in men and women.

But in contrast to the closing mortality gap seen with smoking-related cancers, the gap actually widened for the 3 most common cancers that are thought to be most affected by screening and early detection -- breast, colorectal, and prostate cancer. The researchers saw decreases in death rates for these cancers earlier and to a much larger extent in whites than in African Americans over the 30-year period.

The possible reasons for these findings weren’t addressed in this study, and there are likely several factors that influence these disparities, including tobacco use, sociodemographic factors, and access to care. African Americans have been historically less likely to be screened for breast and colorectal cancers than whites.

According to Cancer Facts and Figures for African Americans 2007-2008, the percentage of African-American adults being screened for colorectal cancer is less than 50%, despite improvements in these numbers in recent years. Compared to white men aged 50 and older, black men over 50 are less likely to get screened for prostate cancer. Black women are now just as likely as white women to get a mammogram to screen for breast cancer, but those efforts have yet to affect death rates. Whites are also more likely to receive appropriate treatment for breast, prostate, lung, or colorectal cancer, according to the study authors.

“This study did not explore the factors that may be influencing the results,” said DeLancey. “We encourage more minority participants to enroll in studies such as Cancer Prevention Study-3 (CPS-3) so we can learn more about what's influencing these disparities.”

“Recent Trends in Black-White Disparities in Cancer Mortality.” Published in the November 2008 issue of Cancer Epidemiology Biomarkers and Prevention (CEBP). First author: John Oliver L. DeLancey. Department of Epidemiology and Surveillance Research, American Cancer Society.