African Americans are at greater risk for colon cancer than other racial groups and should be screened at an earlier age, studies indicate.

Overall, colorectal cancer is the second leading cause of cancer deaths in the United States.

Younger blacks are more likely to have pre-cancerous polyps than younger whites or Hispanics, based on colonoscopy records evaluated in one study.

The other found that African Americans are diagnosed with colorectal cancer at a younger age than whites, confirming results of earlier research that has shown African Americans with this disease also have decreased survival compared with whites.

These two studies highlight important colorectal cancer prevention issues and screening strategies.

Polyps More Common Among African Americans

A retrospective analysis of individuals younger than age 50 who were screened for colon cancer at Nassau University Medical Center in East Meadow, NY, included 177 patients.

In their analysis of abnormal colonoscopy exam results, researchers found that polyps were most common among African Americans, while hemorrhoids were most common among for Caucasians. Hispanics most commonly experienced diverticulosis.

The prevalence of colon polyps among African Americans in this study was 48 percent, while the prevalence in other races was sharply lower: 29 percent in Caucasians and 27 percent in Hispanics. Additionally, African Americans in this study experienced a larger number of polyps on the right side of the colon.

Significantly Lower Age at Diagnosis

In a study of 1,477 patients screened for colorectal cancer between 2000 and 2004, researchers at Coney Island Hospital in Brooklyn, NY, looked at race, age, and location of colorectal cancer.

Of the 177 patients identified with a malignancy, the mean age was 67.4 years when they were diagnosed with colorectal cancer; 41 percent were under 65. African Americans had a significantly lower age at diagnosis: 63.3 years compared to 69.7 for whites.

African Americans demonstrated more right-sided, cancers.

"We found that one quarter of the cancers in African Americans were on the right side of the colon, making these patients more likely to present without specific symptoms, and making colonoscopy a better screening test than sigmoidoscopy," says Dr. Emmanuel Akinyemi, one of the investigators in the Coney Island study.

First Line of Defense

Colonoscopy, rather than sigmoidoscopy, should be considered a "first line" colorectal-cancer screening procedure for African Americans, recommends the American College of Gastroenterology.

This advice is based on the high overall risk, as well as some evidence that African Americans have more right-sided cancers and polyps. The right side of the colon includes the cecum, ascending colon and proximal transverse colon and cannot be reached by flexible sigmoidoscopy.

Colorectal cancer screening in African Americans should begin at age 45, rather than at 50, according to recommendations issued by the American College of Gastroenterology to healthcare providers in March 2005.

Colonoscopy is the preferred method of screening for colorectal cancer and data support the recommendation that African Americans begin screening at a younger age because of the high incidence of colorectal cancer and a greater prevalence of proximal, or right-sided, polyps and cancerous lesions in this population.