JOSEPH S. BAILES, MD
While gastroenterologists and radiologists duke it out over the technical merits of colon cancer screening, new studies strongly suggest that Hispanics and African Americans exhibit different patterns of precancerous lesions, compared with Caucasians, and that these lesions would be best detected by colonoscopy instead of flexible sigmoidoscopy or other screening tests.
Additionally, younger and elderly African Americans are at increased risk for colorectal neoplasia, and these groups warrant screening with colonoscopy, contrary to existing guidelines. Taken together, these studies presented at the 2010 Digestive Disease Week (DDW) conference suggest that current colorectal screening guidelines are inadequate for at-risk minority groups.
Flexible sigmoidoscopy insufficient
Data from a study done at the University of Puerto Rico Cancer Center in San Juan supply evidence that ethnic and gender variations in colorectal neoplasia patterns in Hispanics may have important implications in screening algorithms.
The retrospective study, led by Fernando Ramos-Mercado, MD, director of The Institute of Gastroenterology at the cancer center, ascertained the prevalence and risk factors associated with colorectal neoplasia among asymptomatic Puerto Rican Hispanics.
The patient population consisted of 745 asymptomatic patients (mean age, 59) who underwent a screening colonoscopy between January 2008 and September 2009. Of these 745 patients, 90% had a good or adequate preparation, and visualization of the cecum was possible in 99.7% of them.
Twenty percent of the females and 32% of the males who were screened had colorectal neoplasia (P = .001). However, only two cases of colorectal cancer were detected among those who were screened (0.27% prevalence).
The authors found that the prevalence of colorectal cancer detected on screening was similar to that among non-Hispanic Caucasians in the U.S. Males were twice as likely as females to develop colorectal neoplasia, and males were also more likely to have multiple adenomas and large adenomas, compared with females. Increasing age was associated with increased risk of neoplasia for both genders; Hispanics over age 60 had a 56% increased chance of having colorectal neoplasia, compared with those under age 60 (abstract S1558).
Colorectal neoplasia was located more frequently in the proximal colon in both males and females, which is similar to data reported for African Americans; 65% to 70% of all adenomas detected were located proximally (defined as cecum, ascending colon, or transverse colon).
Family history was not a predictor for increased risk of colorectal neoplasia in this Puerto Rican population.
Dr. Ramos-Mercado said the most important implication of this study is that colonoscopy should be the preferred screening method for asymptomatic Hispanics, as flexible sigmoidoscopy fails to reach the proximal colon.
He also pointed out that colorectal screening rates among Hispanics are dangerously low. "Only 40% are currently screened, despite the fact that colorectal cancer is the second leading cause of death among Hispanic women and the third leading cause of death in Hispanic males. As Hispanics become more acculturated to the U.S. lifestyle, they are losing the protective factor of their diet, which may account for the higher rates of colorectal cancer in U.S. Hispanics, compared with their expected rates in their country of origin," he said.