Racial disparities in stage-specific colorectal cancer mortality rates

For distant stage, decreases were 32.6 percent versus 4.6 percent

A new study finds that while colorectal cancer mortality rates dropped in the most recent two decades for every stage in both African Americans and whites, the decreases were smaller for African Americans, particularly for distant stage disease. The authors say concerted efforts to prevent or detect colorectal cancer at earlier stages in blacks could improve worsening black-white disparities.

Before 1980, colorectal cancer mortality rates for African Americans were lower than those for whites. Since then, however, the pattern of CRC mortality rates has reversed and diverged, so that in 2007, the rate for African Americans was 44 percent higher than for whites. This worsening disparity in mortality rates coincided with the introduction and dissemination of screening and improved treatment for colorectal cancer.

Studies show dissemination of screening and improved treatment for colorectal cancer among African Americans has lagged behind whites. However, the extent to which black-white disparities in mortality rates vary by stage at diagnosis is unknown. To find out, American Cancer Society researchers led by Anthony S. Robbins, M.D., Ph.D., examined disparities in stage-specific colorectal cancer mortality rates using the Incidence-Based Mortality database of the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program.

They found for localized stage, mortality rates decreased 30.3 percent in whites versus 13.2 percent in African Americans. For regional stage disease, those declines were 48.5 percent versus 34.0 percent, respectively. For distant stage, the decreases were 32.6 percent versus just 4.6 percent.

The data indicates that black-white disparities in colorectal cancer mortality increased for each stage of the disease, and that the overall disparity in overall mortality was largely driven by trends for late stage disease. "The widening racial disparity for distant stage has a disproportionate impact on overall CRC mortality disparities because distant stage accounts for approximately 60% of the overall black-white mortality disparity," write the authors.

As to why, the authors cite differences in early detection and differences in treatment. African Americans have historically been less likely than whites to be screened for colorectal cancer. In addition, African Americans who are screened often lack timely follow-up. Meanwhile, studies show the dissemination of improvements in treatment has been uneven. Despite its known survival benefit, adjuvant chemotherapy treatment rates among African American patients with colorectal cancer are disproportionately low relative to whites.