Black people have a higher risk of colorectal cancer (CRC) than white people, but this risk is likely not due to genetics, according to data from a study by researchers from the US Department of Veterans Affairs, Regenstrief Institute and the Indiana University School of Medicine. The study, 'Prevalence of Advanced Colorectal Neoplasia in Veterans', was published in the Journal of Clinical Gastroenterology.
"The next step is determining what is behind this increased risk," said lead author, Dr Thomas Imperiale, Regenstrief Institute research scientist, VA investigator and professor of gastroenterology and hepatology at IU School of Medicine. "Lifestyle and healthcare-related behaviours may explain some of the difference."
In the study, the research team sought to quantify the independent effects of age, sex and race/ethnicity on risk of CRC and advanced neoplasia (AN) in Veterans. They looked at more than 90,000 veterans who underwent a colonoscopy at 18 VA facilities during a seven-year period. In the overall study population, Black veterans had a higher risk of colorectal cancer. However, in a subgroup of people who got routine screenings, the risk was equal for Black patients and white patients, which suggests that the difference is not biological.
Among 90,598 Veterans [mean (SD) age 61.7 (9.4) y, 5.2% (n=4673) were women], CRC and AN prevalence was 1.3% (n=1,171) and 8.9% (n=8,081), respectively. Adjusted CRC risk was higher for diagnostic versus screening colonoscopy [odds ratio (OR)=3.79; 95% confidence interval (CI), 3.19-4.50], increased with age, was numerically (but not statistically) higher for men overall (OR=1.53; 95% CI, 0.97-2.39) and in the screening subgroup (OR=2.24; 95% CI, 0.71-7.05), and was higher overall for Blacks and Hispanics, but not in screening.
AN prevalence increased with age and was present in 9.2% of men and 3.9% of women [adjusted OR=1.90; 95% CI, 1.60-2.25]. AN risk was 11% higher in Blacks than in Whites overall (OR=1.11; 95% CI, 1.04-1.20), was no different in screening, and was lower in Hispanics (OR=0.74; 95% CI, 0.55-0.98). Women had more proximal CRC (63% vs. 39% for men; P=0.03), but there was no difference in proximal AN (38.3% for both genders).
"It could be that Black patients are not getting screened, as suggested by guidelines, or that they respond to early symptoms differently, perhaps delaying seeking treatment for symptoms of colorectal cancer longer than white patients do," said Imperiale. "Screening is one of the most powerful tools for preventing or detecting colorectal cancer early, when it is curable."
The study also found that the risk of colorectal cancer increases for all patients with age.
"Often, Black patients do not have access to screening or the ability to attend an appointment. Historically, this population has also had trust issues with healthcare, all of which could contribute to these disparities," said Regenstrief Research Scientist, Dr NiCole Keith, who was not involved in this project, studies health disparities. "We need to develop a way to make these important tests more accessible to everyone and improve trust in healthcare."