April 4, 2008

Colonoscopy disparities persist: study

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Harvey Murff, M.D., M.P.H.

Colonoscopy disparities persist: study

African-Americans are far more likely to be diagnosed with and to die from colorectal cancer than whites or other minority groups. Despite this increased risk, a new study led by Vanderbilt University Medical Center researchers found that African-Americans are far less likely to undergo colonoscopy screening than whites, even when both groups have a family history of colorectal cancer.

Lead author Harvey Murff, M.D., M.P.H., assistant professor of Medicine and lead author of the study published in the Archives of Internal Medicine, said family history is a strong predictor of colorectal cancer risk

“Individuals who have a first-degree relative with colorectal cancer have a twofold to threefold increased risk of developing the disease and they are likely to be diagnosed with the malignancy 10 years earlier than patients without this family history,” explained Murff. “We wanted to know if people who knew about their inherited risk factors would be more likely to undergo screening.”

The National Cancer Institute estimates 148,810 Americans will be diagnosed with colon or rectal cancer in 2008, with 49,960 deaths from both types of cancer. In addition to family history, a diet high in total fat and meat, and cigarette smoking are risk factors for these cancers.

The researchers, representing Vanderbilt-Ingram Cancer Center, Meharry Medical College, the U.S. Department of Veterans Affairs and the International Epidemiology Institute, looked at baseline data from 41,830 patients who are part of the Southern Community Cohort Study, an ongoing study investigating cancer incidence and mortality disparities across racial, and urban versus rural populations in 12 Southern states.

They found African-Americans who had multiple first-degree relatives diagnosed with colorectal cancer were about half as likely as whites with the same family history to have undergone recommended screening tests like colonoscopy during the previous five years. For both groups, the most common reason given for not having the screening tests was the lack of a recommendation from their health care provider, with African-Americans far more likely to express this answer.

During a colonoscopy, physicians can look inside parts of the digestive tract for signs of cancer. Colonoscopy involves threading a tube with a camera through the colon and small intestines, searching for masses or polyps. The device can remove the polyps which often become malignant if left intact. Removal of colon polyps is now considered the best method to prevent colon cancer, so access to this procedure is crucial for patients at high risk for the disease.

Most clinical guidelines recommend screening for colorectal cancer beginning at age 50 but for patients with a family history of this type of cancer, the screenings should begin at age 40.

“Since a family history of colorectal cancer is strongly associated with increased risk, even small inequities in screening can translate into large differences in cancer outcomes,” said Murff. “Clearly we need to do a better job of closing this gap in screening, especially for high-risk patients in underserved populations.”