Racial disparities decline for cancer in Missouri

September 24, 2008

Cancer death rates in the United States are highest among African Americans, but a new report shows that in Missouri the disparity in cancer incidence and death between African Americans and whites is declining. As a result, cancer incidence (the rate of newly diagnosed cases) between the races is equal, although the death rate will probably remain higher for African Americans for some time.

The report will be published in an upcoming issue of Missouri Medicine. The lead author is Mario Schootman, Ph.D., co-leader of the Prevention and Control Program at the Siteman Cancer Center at Washington University School of Medicine and Barnes-Jewish Hospital.

"A lot of effort has been made to reduce cancer racial disparity in Missouri," says Schootman, also chief of the Division of Health Behavior Research and associate professor of epidemiology and medicine. "But there is still work to be done, especially in decreasing cancer mortality. Ideally, cancer will become just another bump in the road — an illness that people will be able to live with for many decades and keep under control."

The report shows that in 1996, the rate of new cancer cases was 18 percent higher for African-American Missourians but declined to six percent higher by 2003, the last year for which the data were analyzed. If this downward trend continues, the disparity in new cancer cases between African-American and white Missourians will have disappeared when 2006 data is analyzed, Schootman says.

On average, the overall Missouri cancer incidence rate decreased by 0.8 percent per year, possibly reflecting a drop in smoking rates and other preventive measures. The disparity in incidence between African Americans and whites might have arisen from such factors as differences in physical activity, weight, vitamin D deficiency, diabetes, diet and occupational exposure to pollutants, according to the report.

On the other hand, racial disparity in overall cancer death rates remains. In 2005, the last year for which the data were analyzed, the cancer death rate was 28 percent higher for Missouri's African Americans than for whites. This was down from a 48 percent higher cancer death rate for African Americans in 1990, but the slow pace of the decrease means that racial disparity in cancer deaths will probably continue for several more decades unless more aggressive interventions are used, Schootman says.

Schootman also individually analyzed four major cancers — colorectal, breast, prostate and lung — and found some trends contrary to the overall cancer trends. Instead of decreasing, the gap between African Americans and whites for colorectal cancer death rates remained as large as ever. The death rate for this cancer declined among members of both groups during the study period of 1990 to 2005, but it remained about 42 percent higher for African-American than white Missourians.

"In Missouri, African Americans were more likely to be screened for colorectal cancer than whites during the timeframe of our statistical analysis," Schootman says. "But that doesn't appear to have made enough of a difference in the rate of death yet. The racial disparity in colorectal cancer death rate is one of the most serious concerns raised by this study."

Schootman explains that there are four possible reasons for the higher colorectal cancer death rate: less aggressive treatment, more advanced cancer at time of diagnosis, less patient engagement in lifestyles that reduce risk of dying after diagnosis — such as exercise and weight loss — and more physical characteristics that increase risk of dying — such as a higher body fat percentage.

Racial disparity in breast cancer deaths increased during the study period. African American women in Missouri had a nine percent lower incidence of breast cancer than did white Missourians at the end of the study period but had a 46 percent higher breast cancer death rate. Schootman says that other studies suggest that lack of insurance, fear of testing, delay in seeking care and unfavorable tumor characteristics all contribute to this disparity.

Another major concern raised by the study was the much higher death rate from prostate cancer among African Americans. Despite a decline in racial disparity, African-American Missourians died at a 116 percent higher rate from prostate cancer than white Missourians. Schootman says that a possible explanation is that African Americans adopted prostate cancer screening and new therapies later than did white Missourians.

Racial disparity in lung cancer deaths decreased during the study period, but remained 15 percent higher for African-American Missourians. Other research suggests several reasons for the disparity: differences in referral to specialists, less patient acceptance of therapy due to distrust or misunderstanding and differences in availability of treatment.

To further reduce disparities in cancer incidence and death, state and local health departments, primary care associations, medical and community-based organizations, large employers and health care companies need to focus on providing equal access to preventive and treatment services.

The Siteman Cancer Center's PECaD (Program for the Elimination of Cancer Disparities addresses racial disparities in cancer in the St. Louis region.

"PECaD's efforts to reduce breast cancer disparities in the region include promoting mammography through outreach and our mobile mammography van, together with access to diagnostic and treatment services," says PECaD director, Graham Colditz, M.D., Dr.P.H., the Niess-Gain Professor and associate director of Prevention and Control at the Siteman Cancer Center. "Similar multilevel approaches will be necessary to reduce disparities."

Source: Washington University in St. Louis