by Todd Neale

The greater burden of colorectal cancer in the black community appears to be related to healthcare utilization, and not biology, researchers found.

Similar proportions of black and white patients had polyps or masses detected by flexible sigmoidoscopy, but black patients were less likely than whites to have the recommended follow-up colonoscopy (62.6% versus 72.4%), according to Adeyinka Laiyemo, MD, MPH, of Howard University in Washington, and colleagues.

After adjustment for age, education, sex, body mass index, smoking, family history of colorectal cancer, colon examination within the previous three years, personal history of polyps, and screening center, blacks were 12% less likely to have a colonoscopy (RR 0.88, 95% CI 0.83 to 0.93), the researchers reported in the Journal of the National Cancer Institute.

There were no significant differences based on race in the characteristics of the lesions found during colonoscopy.

“This suggests that the biology of colorectal cancer may not be materially different by race, at least in the early stages of carcinogenesis, but instead that healthcare utilization differences among the races may play a more important role in the observed disparities in colorectal cancer,” they wrote.

They said screening programs must have an adequate diagnostic component to eliminate racial disparities.

In an accompanying editorial, John Ayanian, MD, MPP, of Harvard, highlighted an effort in New York City to promote colonoscopy through public education, improved tracking systems, and broad use of patient navigators. The program resulted in increased screening rates, and racial disparities disappeared.

“Such local success in promoting colorectal cancer screening and eliminating racial disparities must now be extended to other communities and states in which screening rates continue to lag and disparities persist,” he wrote.

To explore the origins of racial disparities in colorectal cancer, Laiyemo and colleagues turned to the Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Screening Trial, an ongoing multicenter, randomized controlled trial evaluating the effect of screening on cancer mortality.

They looked at data from 57,561 white patients and 3,011 black patients ages 55 to 74 who underwent flexible sigmoidoscopy without biopsy at 10 U.S. centers.

Polyps or mass lesions were found in 25.5% of blacks and 23.9% of whites (P=0.257). All were advised to get a follow-up colonoscopy, which was not paid for by the trial.

Of those, 72.4% of whites and 62.6% of blacks had a colonoscopy within one year.

The study investigators reviewed the results and found no significant difference between the races in the prevalence of polyps, advanced adenomas, advanced pathology in small adenomas (high-grade dysplasia or villous histology in adenomas <10 mm), or colorectal cancer.

Black patients, however, were more likely to have advanced adenoma in the proximal colon (RR 1.56, 95% CI 1.13 to 2.14). Although that suggests a biological difference between whites and blacks, the researchers said, the finding could be the result of small sample sizes or residual confounding.

The reasons for lower follow-up rates among blacks are unknown, they said, but several factors could be contributing.

Blacks may have lower socioeconomic status, they said. Although that was not measured in this study, educational level — sometimes used as a marker of socioeconomic status — was lower among black patients.

Also, the need for multiple tests could discourage follow-up testing.

Finally, a “lack of knowledge of cancer prevention may contribute to low uptake of diagnostic testing, and lack of cultural competence on the part of care providers may also constitute a barrier to healthcare utilization,” they wrote.

When the patients were stratified by education, the difference in use of colonoscopy was significant only among those with a high school education or less.

Because the black patients in the study were more educated and health conscious than their general population counterparts, the results could be an underestimation, the researchers said.

Laiyemo’s group listed some limitations of the study, including the fact that flexible sigmoidoscopy only detects lesions in the distal colon. In addition, blacks were underrepresented in the study.

Todd Neale MedPage Today staff writer.

Originally published in MedPage Today. Visit MedPageToday.com for more oncology news.