The greater colorectal cancer incidence and mortality in African Americans, compared with other races, may not be due to increased colon polyp prevalence, according to a study from the Medical University of South Carolina in Charleston. The authors said that it was not clear where along the adenoma-carcinoma sequence the African-American population's excess cancer risk lies.
JOSEPH ROMAGNUOLO, MD
Eli Penn, MD, Joseph Romagnuolo, MD, and colleagues from the university's Digestive Disease Center searched their institution's detailed endoscopy database and found 3,732 patients with minimal or no symptoms who underwent their first screening colonoscopy or colonoscopy due to a positive fecal occult blood test (FOBT) from 1996 to 2006. Of these patients, 761 (20.4%) had polyps.
Multivariate analysis showed that age older than 65 years and male sex, but not race, independently predicted the presence of polyps (odds ratio 1.35, 1.67, and 1.04, respectively). In addition, male sex, but not race, predicted right-sided polyps, and the presence of three or more polyps; the latter was also predicted by a positive FOBT result (Arch Intern Med 170:1127-1132, 2010).
Of the 761 patients with polyps, 60% had adenomas, and 57 of these patients had a follow-up colonoscopy at the university a median of 3.6 years after their initial screening. Polyps recurred in 35 patients (71.4% of African Americans [AAs] and 60% of whites). Neither male sex nor race significantly predicted polyp recurrence. A random sample of 100 pathology reports (50 AAs and 50 whites) of polypectomy specimens confirmed no significant racial difference in the proportion of those with polyps having at least one adenomatous polyp (68% of whites vs 60% of AAs, P= .60).
Based on these findings, the authors suggest that colon cancer screening guidelines should be stratified by sex but not race. Due to the small number of patients who underwent follow-up colonoscopy, more data are needed to make recommendations about stratified surveillance intervals by sex or race, but the limited data from this study do not support stratification at this time, the authors noted.
"A significantly higher polyp prevalence and incidence do not seem to serve as the explanation [for AAs' more advanced cancers at presentation and presentation at a younger age]," the authors concluded. They speculated that the rate of malignant transformation of adenomas may be different in AAs or that other advanced colon cancer features are more common in AAs.