Emerging and widening colorectal carcinoma disparities between Blacks and Whites in the United States (1975-2002)

Abstract

Background: Colorectal carcinoma (CRC) is the fourth most common cancer diagnosed and the second most common cause of cancer death in the U.S. Incidence and mortality rates have decreased since the mid-1980s, although more among Whites than Blacks.

Methods: To determine if these racial differences were changing over time, we examined CRC rates in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program (1975-2002). Rates were stratified by gender, race, anatomic subsite, historic stage, and grade.

Results: CRC rates were higher among men than women and higher among Blacks than Whites, with Black men having the highest rates during the latter years. Prior to the mid-1980s, male CRC rates were actually higher among Whites than Blacks; after which there was ethnic crossover with Black rates higher than White rates, and the gaps are widening. Proximal and transverse CRCs were more common and rectal cancers were less common among Blacks than Whites. Over time, rates for localized and regional stages increased among Blacks and decreased among Whites. Rates for distant stages declined for both racial groups, although less among Blacks. Black-to-White rate ratio for distant stage was approximately 1.30. Notably, Blacks compared with Whites had lower grade tumors, despite higher stages and mortality rates.

Conclusions: CRC racial disparities have emerged and widened for three decades. These temporal trends probably reflect complicated racial differences between screening practice patterns and etiologic factors.