At-Home Colorectal Cancer Testing and Follow-Up Vary by Ethnicity

Damian McNamara, MA

June 03, 2022

Doctors were significantly less likely to order colorectal cancer screening with the at-home test Cologuard (Exact Sciences Corp) for Black patients and were more likely to order the test for Asian patients, new evidence reveals.

Investigators retrospectively studied 557,156 patients in the Mayo Clinic health system from 2012 to 2022. They found that Cologuard was ordered for 8.7% of Black patients, compared to 11.9% of White patients and 13.1% of Asian patients.

Both minority groups were less likely than White patients to undergo a follow-up colonoscopy within 1 year of Cologuard testing. Cologuard tests the stool for blood and DNA markers associated with colorectal cancer.

Although the researchers did not examine the reasons driving the disparities, lead investigator Ahmed Ouni, MD, told Medscape Medical News that "it could be patient preferences...or there could be some bias as providers ourselves in how we present the data to patients."

Ouni presented the findings on May 22 at Digestive Disease Week (DDW) 2022, held in person in San Diego and virtually.

Breakdown by Physician Specialty

"We looked at the specialty of physicians ordering these because we wanted to see where the disparity was coming from, if there was a disparity," said Ouni, a gastroenterologist at Mayo Clinic in Jacksonville, Florida.

Just over half (51%) of the patients received care from family medicine physicians, 27% received care from internists, and 22% were seen by gastroenterologists.

Family physicians ordered Cologuard testing for 8.7% of Black patients, compared to 16.1% of White patients, a significant difference (P < .001). Internists ordered the test for 10.5% of Black patients and 11.1% of White patients (P <  .001). Gastroenterologists ordered Cologuard screening for 2.4% of Black patients and 3.2% of White patients (P = .009).

Gastroenterologists were 47% more likely to order Cologuard for Asian patients, and internists were 16% more likely to order it for this population than for White patients. However, the findings were not statistically significant for the overall cohort of Asian patients when the researchers adjusted for age and sex (P = 0.52).

Black patients were 25% less likely to have a follow-up colonoscopy within 1 year of undergoing a Cologuard test (odds ratio [OR], 0.75; 95% CI, 0.60 – 0.94), and Asian patients were 35% less likely (OR, 0.65; 95% CI, 0.52 – 0.82).

Ongoing and Future Research

Of the total study population, only 2.9% self-identified as Black; according to the 2020 US Census, 12.4% of the population of the United States are Black persons.

When asked about the relatively low proportion of Black persons in the study, Ouni replied that the investigators are partnering with a Black physician group in the Jacksonville, Florida, area to expand the study to a more diverse population.

Additional plans include assessing how many positive Cologuard test results led to follow-up colonoscopies.

The investigators are also working with family physicians at the Mayo Clinic to examine how physicians explain colorectal cancer screening options to patients and are studying patient preferences regarding screening options, which include Cologuard, fecal immunochemical test (FIT)/fecal occult blood testing, CT colonography, and colonoscopy.

"We're analyzing the data by ZIP code to see if this could be related to finances," Ouni added. "So, if you're Black or White and more financially impoverished, how does that affect how you view Cologuard and colorectal cancer screening?"

Some Unanswered Questions

"Overall this study supports other studies of a disparity in colorectal cancer screening for African Americans," John M. Carethers, MD, told Medscape Medical News when asked to comment. "This is known for FIT and colonoscopy, and Cologuard, which is a genetic test in addition to FIT, appears to be in that same realm.

"Noninvasive tests will have a role to reach populations who may not readily have access to colonoscopy," said Carethers, John G. Searle Professor and chair of the Department of Internal Medicine and professor of human genetics at the University of Michigan in Ann Arbor. "The key here is if the test is positive, it needs to be followed up with a colonoscopy."

Carethers added that the study raises some unanswered questions, for example, Does the cost difference between testing options make a difference?

"FIT is under $20, but Cologuard is generally $300 or more," he said. What percentage of the study population were offered other options, such as FIT? How does insurance status affect screening in different populations?

"The findings should be taken in context of what other screening options were offered to or elected by patients," agreed Gregory S. Cooper, MD, professor of medicine and population and quantitative health sciences at Case Western Reserve University and a gastroenterologist at University Hospitals Cleveland Medical Center in Ohio.

According to guidelines, patients can be offered a menu of options, including FIT, colonoscopy, and Cologuard, Cooper told Medscape Medical News.

"If more African Americans elected colonoscopy, for example, the findings may balance out," said Cooper, who was not affiliated with the study. "It would also be of interest to know if the racial differences changed over time. With the pandemic, the use of noninvasive options, such as Cologuard, have increased."

"I will note that specifically for colonoscopy in the United States, the disparity gap had been closing from about 15% to 18% 20 years ago to about 3% in 2020 pre-COVID," Carethers added. "I am fearful that COVID may have led to a widening of that gap again as we get more data.

"It is important that noninvasive tests for screening be a part of the portfolio of offerings to patients, as about 35% of eligible at-risk persons who need to be screened are not screened in the United States," Carethers said.

The study was not industry sponsored. Ouni and Carethers report no relevant financial relationships. Cooper has received consulting fees from Exact Sciences Corp.

Digestive Disease Week (DDW) 2022: Abstract Su1012. Presented May 22, 2022.

Damian McNamara is a staff journalist based in Miami. He covers a wide range of medical specialties, including infectious diseases, gastroenterology, and critical care. Follow Damian on Twitter: @MedReporter.

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