Colorectal Cancer Mortality and Racial Disparity Varies Across U.S. Cities

SAN FRANCISCO – Racial disparities in death rates from colorectal cancer vary considerably across cities in the United States, according to results of a study presented at the 12th AACR Conference on The Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved, held here Sept. 20-23.

Colorectal cancer (CRC) is the second leading cause of cancer death in the United States. African Americans have a 43 percent higher CRC mortality rate than whites, explained the study’s lead author, Abigail Silva, PhD, MPH, assistant professor in the Parkinson School of Health Sciences and Public Health at Loyola University Chicago.

“Reduction in CRC mortality and racial disparities can be achieved, in part, by addressing modifiable factors like smoking and obesity, but also by implementing programs and policy changes at the city level, as more than 80 percent of invasive cancer cases occur within urban areas,” Silva said.

In this study, Silva and colleagues from the Sinai Urban Health Institute and DePaul University sought to calculate overall and race-specific average annual CRC mortality rates for the 30 most populous cities in the United States, and to quantify racial disparities. They used mortality data from 2013-2017 from the Centers for Disease Control and Prevention’s National Center for Health Statistics and the U.S. Census Bureau’s American Community Survey to calculate death rates and to ascertain the number of excess deaths due to racial disparity.

According to the study, the overall CRC mortality rate for the United States was 14.8 deaths per 100,000 people. The mortality rate for blacks was 20.9 per 100,000, and for whites it was 14.7 per 100,000, with a rate difference of 6.27 per 100,000.

This equates to 2,252 excess deaths of black Americans from colorectal cancer each year, Silva said. Excess deaths represent how many more black deaths occurred than would be expected if the black population had the same mortality rate as their white counterparts, she explained.

Of the 30 cities in the study, 25 had a racial disparity in the CRC mortality rate. The highest disparity was in Washington, D.C., with a rate difference of 13.65. Philadelphia had the smallest disparity, with a rate difference of 3.55.

Other key findings:

“City-level mortality rates ranged from a low of 11.4 deaths per 100,000 people in San Jose to a high of 32.6 per 100,000 in Las Vegas.

“Among the 25 cities with a racial disparity, Seattle and Portland had the fewest excess black deaths, with three each. Chicago fared the worst, with 96 excess black deaths due to CRC disparities.

“Twelve cities recorded lower CRC mortality rates than the United States as a whole. However, seven of these still had higher-than-average black/white disparities.

Silva plans to present further data at the conference.

She said this study provides valuable information on the way disparities may vary considerably from one city to the next. Such information can be used by local governments and city leaders to assess the success of existing prevention and screening programs, and provide an impetus to develop further resources to narrow cancer disparities.

“Local level data are critical for improving cancer outcomes for populations and addressing health inequities,” Silva said. “Each city can use this information to make real, evidence-based changes in policies, services, and funding.”

Many cities and towns have seen improvement in cancer disparities due to innovative programs designed to eliminate the gap between racial groups. For example, she cited a recent study that showed that breast cancer mortality disparity narrowed in the years after the city created the Metropolitan Chicago Breast Cancer Task Force to improve access to high-quality health care. She said her study could provide support for similar initiatives.

Silva said one limitation of this study is that it encompassed only the 30 most populous U.S. cities, and it did not study Hispanic mortality rates. She said future research could target these populations.

The cities included in the study, from most populous to least populous, are New York; Los Angeles; Chicago; Houston; Philadelphia; Phoenix; San Antonio; San Diego; Dallas; San Jose, California; Austin, Texas; Jacksonville, Florida; Indianapolis; San Francisco; Columbus, Ohio; Fort Worth, Texas; Charlotte, North Carolina; Detroit; El Paso, Texas; Memphis, Tennessee; Seattle; Denver; Washington, D.C.; Boston; Nashville, Tennessee; Baltimore; Portland, Oregon; Oklahoma City; Louisville, Kentucky; and Las Vegas.

This study was funded in part by the Sinai Urban Health Institute Research Fellowship program. Silva declares no conflicts of interest.