Colorectal Cancer in African Americans
Bharat K. Misra, M.D.
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| In 2001, approximately 140,000 Americans were diagnosed with colorectal cancer and about 57,000 died from this disease.
Colorectal cancer is second only to lung cancer as a cause of cancer death in the United States. In recent years, reports
have emerged to suggest that African Americans may have a higher rate of death from colon cancer compared with other
ethnic groups. Research investigating the origins of this phenomenon has considered issues such as environmental factors, access
to diagnostic testing and healthcare, cultural factors which may delayed diagnosis or affect treatment choices, biological
features of the disease, and physician attitudes. The results are beginning to provide insights that could be useful in designing
strategies for early detection and management of colon cancer in African Americans.
The incidence of colorectal cancer and of colon polyps varies by country of birth, and rises rapidly in populations which migrate from countries of low risk to high risk areas. This indicates that environmental factor such as diet plays an important role. Most colorectal cancers arise from adenomatous polyps. The prevalence of adenomas can be used to track the likelihood of colon cancer occurring in a population. Adenomas seldom develop in African Americans who reside in South Africa whereas the prevalence rates for African Americans who live in New Orleans is much higher than those living in South Africa and is comparable to rates in the city's white population. It appears that race per se is not an important independent determinant of colorectal adenomas. The distribution of polyps in the colon may vary, however, between ethnic groups. There is evidence that adenomas occur more commonly in the middle and right colon in African Americans. These are lesions which would not be detected by the standard 60 centimeter office flexible sigmoidoscope. African Americans also have a higher frequency of synchronous polyps, meaning the case of having more than one polyp present at the same time. These findings suggest that sigmoidoscopy, a test sometimes recommended as a screening test for colon caner, may not be pertinent to the African American population, and that complete colonoscopy is preferable. Between 1985 and 1997 the incidence rates and mortality rates of colorectal cancer in the United States declined at an annual rate of 1.6% and 1.8%, respectively. Unfortunately, these encouraging trends are not evident in the African American population where these rates have been stable over the same period. In Duval County, this results in incidence rates for non-white males and females that are higher than for whites. This data for Duval County (Jacksonville, FL) does not distinguish between African Americans and other non-white populations but African Americans are the predominant non-white group in Duval County. There is evidence that colorectal cancer is not necessarily a more aggressive disease in African Americans. The disease outcomes may be similar among patients who receive equal access to medical care and have a similar socioeconomic background. There is evidence, however, that African Americans are less likely to undergo screening tests for colon cancer. In summary, improvements in the incidence and death rates which have occurred among US whites in the in the last part of the 20th Century have not extended to African Americans. We need to redouble our efforts to provide to physicians and to this population information about colon cancer. We should offer colonoscopy as the preferred screening procedure. A task force of the Duval County branch of the American Cancer Society has been working on this problem since 2001. June/July, 2002/ Jacksonville Medicine [dcms-footer.htm] |