Higher interval colorectal cancer incidence in blacks

Last Updated: 2017-05-22

By Will Boggs MD

NEW YORK (Reuters Health) - The incidence of interval colorectal cancer, i.e., cancer that develops after a negative colonoscopy but before the next recommended test, is more than 30% higher in blacks than in whites, according to a population-based study.

"This study identified disparities in interval colorectal cancer as well as quality of colonoscopy, the most common test used for colorectal cancer screening,” Dr. Stacey A. Fedewa from the American Cancer Society, Atlanta, Georgia told Reuters Health by email. “However, I think it’s important to relay the message that screening for colorectal as well as leading a healthy life (i.e., being physically activity, having a healthy diet) are important ways that people can reduce their risk of colorectal cancer.”

Blacks have colorectal cancer incidences 22% to 27% higher than whites, with about 40% of these disparities attributed to lower utilization of screening among black people.

To assess whether these disparities extend to interval colorectal cancer, Dr. Fedewa and colleagues used data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program on Medicare patients ages 66 to 75.

They also assessed whether physicians' polyp detection rate (PDR) accounted for the potential differences between blacks and whites in the risk for interval CRC.

The probability of interval CRC was 7.1% in blacks, 5.8% in whites, 4.4% in Hispanics, and 3.8% in Asians, the authors reported online May 22 in Annals of Internal Medicine.

More blacks (52.8%) than whites (46.2%) received their index colonoscopy from physicians in the lowest two PDR quartiles, and the risk for interval CRC was significantly higher in patients whose colonoscopy was performed by physicians in the bottom three quartiles than in those whose colonoscopy was performed by physicians in the top quartile.

Adjustments for PDR did not meaningfully alter the differences between blacks and whites in occurrence of interval CRC. However, blacks had higher risk for interval CRC when colonoscopies were performed by physicians in the top two PDR quartiles, but not in the lower quartiles.

Black patients had higher risk than white patients for interval CRC in the distal colon and rectum, but not in the proximal colon.

“I was a little surprised that although quality of colonoscopy was associated with interval CRC, it did not account for the racial disparities observed in our study,” Dr. Fedewa said. “Also, I was initially surprised to see that the difference in interval CRC between blacks and (whites) were most pronounced in patients receiving colonoscopy from higher-quality physicians until one of my co-authors (Dr. Chyke Doubeni) brought up an important point - that disparities in outcomes and healthcare utilization often manifest as higher-quality or new interventions become available.”

“Our findings and those reported elsewhere highlight the importance of attentive examination of the colon and rectum during colonoscopy to achieve the optimal benefit of this test,” she said.

“Future studies examining this issue are warranted, given the higher overall risk for interval CRC in black populations as well as the larger disease burden in this group,” the researchers conclude.

SOURCE: http://bit.ly/2qdcRjm

Ann Intern Med 2017.