Minorities benefit from more sophisticated colon cancer screening

ABSTRACT: Current guidelines may be inadequate in at-risk African-American and Latino populations.

JOSEPH S. BAILES, MD
Editor

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.

"As Hispanics become more acculturated to the U.S. lifestyle, they are losing the protective factor of their diet" - FERNANDO RAMOS-MERCADO, MD

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.

African Americans should screen at earlier age

Current guidelines need to be revisited for African Americans, according to two separate studies. According to the results of both, younger African Americans (age 40 to 49) were more likely than those age 50 to 59 to develop high-grade dysplasia, while blacks older than age 75 were at increased risk of adenomas-and the detection rate was even higher among those with a history of advanced adenomas.

SHASHIDEEP SINGHAL, MD

Shashideep Singhal, MD, a resident in internal medicine at the Brooklyn Hospital Center in New York, reviewed the screening records of 510 elderly African Americans, Hispanic Americans, and Asian Americans with complete colonoscopy records at the hospital. In these populations, patients with a prior history of advanced adenomas or colorectal cancer were more likely to have adenomas detected during screening, compared to those with no prior history (18% vs 16.1%, respectively).

VANTAGE POINT

JOHN CARETHERS, MD Invaluable information for driving optimal care

These types of studies are important as the healthcare community determines which ethnicities and ages are at higher risk for developing neoplasia and cancer, said Dr. Carethers, chair of the internal medicine department at the University of Michigan in Ann Arbor.

"This new information on screening is invaluable as we strive to provide the most affected populations with optimal medical care," he said. "Race is one of the least studied factors related to risk of colorectal cancer. The 2008 multisociety screening guidelines include seven different tests for detection of noncancerous polyps and adenomas, but there are no specific recommendations for race and ethnicity."

African Americans had the highest rate of detection of adenomas and colorectal cancer: 20.1% adenoma detection rate and 2.3% colorectal cancer detection rate. Moreover, African Americans had a higher proportion of advanced adenomas detected on the proximal side of the colon, suggesting that colonoscopy should be the preferred screening method in this population (abstract W1465).

This study did not examine detection of adenomas and colorectal cancer in Caucasian patients, so there is no basis for comparison with the ethnic groups included in the study, Dr. Singhal said.

A second study compared the results of colonoscopy screening in 335 African Americans aged 40 to 49 with those aged 50 to 59. Adenomatous polyps were detected in 22.3% of the younger cohort vs 19.7% of the older cohort. Of the polyps detected, 4.5% were high-grade dysplasia in the younger group vs 0.7% in the older group.

"Our findings support the recommendation that African Americans should consider beginning screening for colorectal cancer at an earlier age," said lead author Frank Friedenberg, MD, professor of medicine at Temple University in Philadelphia. He added that prospective trials are needed, and also that the African-American community should be educated about their increased risk for colorectal cancer at a younger age (abstract 1039).

"Any test is better than none," Dr. Friedenberg said. In average-risk patients a two-part screening strategy using FOBT can be used. In those who are FOBT negative a sigmoidoscopy can be performed and those with a positive test would undergo colonoscopy. This strategy would detect 75% of colorectal neoplasms and require far less utilization. But for higher-risk patients, such as Hispanics, African Americans, and those with a family history, he recommended colonoscopy to find proximal polyps that would be missed by sigmoidoscopy.