Racial Disparities in Incidence of Young-Onset Colorectal Cancer and Patient Survival

Abstract

Increasing rates of young-onset colorectal cancer (CRC) have attracted substantial research and media attention, but we know little about racial disparities among younger adults with CRC. We examined racial disparities in young-onset CRC by comparing CRC incidence and relative survival among younger (age <50 years) adults, in 2 time periods. Using data from the Surveillance, Epidemiology, and End Results program of cancer registries, we estimated CRC incidence rates (per 100,000 persons ages 20 – 54 years) from 1992 through 2014, for different time periods (1992–1996 vs 2010–2014) and races (white vs black). Relative survival was calculated as the ratio of observed survival to expected survival in a comparable, cancer-free population. From 1992–1996 to 2010–2014, CRC incidence increased from 7.5/100,000 to 11.0/100,000 in white individuals and from 11.7/100,000 to 12.7/100,000 in black individuals. The increase in rectal cancer was larger in whites (from 2.7/100,000 to 4.5/100,000) than in blacks (from 3.4/100,000 to 4.0/100,000); in the 2010–2014 time period, black and whites had similar rates of rectal cancer. Compared to whites, blacks had smaller increases in relative survival with proximal colon cancer but larger increases in survival with rectal cancer (from 55.3% to 70.8%). In an analysis of the Surveillance, Epidemiology, and End Results database, we found racial disparities in incidence of young-onset CRC and patient survival for cancer of the colon, but minimal difference for rectal cancer. Well-documented and recent increases in young-onset CRC have been largely due to increases in rectal cancer, especially in whites. The incidence of colorectal cancer is increasing in younger adults (age <50 years). The factor that has made the largest contribution to the increase in CRC among younger adults has been increasing rates of rectal cancer, which is more prominent among whites. Our findings provide clues for understanding reasons why incidence has increased.