Disparities in survival improvement for metastatic colorectal cancer by race/ethnicity and age in the United States

Previous studies documented significant increase in overall survival for metastatic colorectal cancer (CRC) since the late 1990s coinciding with the introduction and dissemination of new treatments. We examined whether this survival increase differed across major racial/ethnic populations and age groups.

We identified patients diagnosed with primary metastatic colorectal cancer during 1992–2009 from 13 population-based cancer registries of the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program, which cover about 14 % of the US population. The 5-year cause-specific survival rates were calculated using SEER*Stat software.

From 1992–1997 to 2004–2009, 5-year cause-specific survival rates increased significantly from 9.8 % (95 % CI 9.2–10.4) to 15.7 % (95 % CI 14.7–16.6) in non-Hispanic whites and from 11.4 % (95 % CI 9.4–13.6) to 17.7 % (95 % CI 15.1–20.5) in non-Hispanic Asians, but not in non-Hispanic blacks [from 8.6 % (95 % CI 7.2–10.1) to 9.8 % (95 % CI 8.1–11.8)] or Hispanics [from 14.0 % (95 % CI 11.8–16.3) to 16.4 % (95 % CI 14.0–19.0)]. By age group, survival rates increased significantly for the 20–64-year age group and 65 years or older age group in non-Hispanic whites, although the improvement in the older non-Hispanic whites was substantially smaller. Rates also increased in non-Hispanic Asians for the 20–64-year age group although marginally nonsignificant. In contrast, survival rates did not show significant increases in both younger and older age groups in non-Hispanic blacks and Hispanics.

Non-Hispanic blacks, Hispanics, and older patients diagnosed with metastatic CRC have not equally benefitted from the introduction and dissemination of new treatments.