Colon Cancer in African Americans

by: Bharat Misra, M.D.

In 2009, there were an estimated 147,000 new cases of colorectal cancer (CRC) in the United States and 50,000 related deaths. Colorectal cancer is second only to lung cancer as a cause of cancer death in the United States. African Americans have the highest incidence of CRC of any racial or ethnic group (1-5).  The reasons for higher rates of CRC in African Americans is unclear, however, nutritional factors and an increased incidence of obesity may contribute (6-11). Also implicated are higher rates of smoking and lower rates of access to healthcare. The 2000 census data indicate that 24% of African Americans live in poverty compared to 8% of Caucasians. African Americans are less likely to have health insurance, leaving them with fewer options to access health care including preventive health services such as CRC screening/ colonoscopy (12-17). It is also important to note that CRC presents at an earlier age in African Americans than Caucasians with one study finding that 10.6% of African Americans were diagnosed with CRC prior to the age of 50 years while only 5.5% of Caucasians were diagnosed with CRC prior to the age of 50 years (4). It has also been hypothesized that there may be genetic differences between African Americans and Caucasians which could explain the earlier age of CRC diagnosis in African Americans.

Survival when diagnosed with CRC is also significantly less in African Americans than Caucasians with a 5 year survival rate in African Americans of 53% versus 63% in Caucasians (1). It is well established that the earlier CRC is diagnosed (lower the stage at diagnosis) the greater the likelihood of survival. In African Americans the number of cases that present with stage IV disease (distant metastasis) is higher (9-11). Interestingly, survival for African Americans is lower than Caucasians even with the same stage of disease (17-19). It has been suggested that this difference is largely attributable to differences in access to medical care. When African Americans and Caucasians had equal access to medical care survival rates were similar.

The location of colon cancer is more likely to be on the right side (proximal colon) in African Americans. In one large study of over 30,000 patients (approximately 10% African American) there were significantly more proximal cancers in African Americans, women and those with advanced age (20). This predilection to develop more right sided colon cancer has led some to advocate colonoscopy rather than flexible sigmoidoscopy for CRC screening in African Americans (21-23).

Colonoscopy is considered the “gold standard” for CRC screening. The identification and removal of adenomas by colonoscopy (using an every 10 year strategy) has been shown to result in a 76-90% reduction in CRC compared to an unscreened population. (24). In an average risk population, colonoscopy detects more than double the number of adenomas as does flexible sigmoidoscopy and is substantially superior to barium enema for adenoma detection (25). It has also been reported that synchronous polyps (polyps occurring at the same time in different locations in the colon) may be more likely in African Americans which also suggests that colonoscopy may be a preferred screening technique in this group. Consensus guidelines suggest that average risk individuals in the population should begin CRC screening at 50 years of age. The American College of Gastroenterology 2008 CRC screening guideline, however, specifically addressed the increased risk of CRC in African Americans and recommended that African Americans begin average risk CRC screening at the age of 45 years rather than 50 years (26).

In summary, African Americans have an increased incidence of CRC with increased mortality from the disease compared to Caucasians. It is more likely that African Americans will have right sided CRC that presents at an earlier age. Recent decreases in CRC incidence rates among Caucasians have not been seen to the same degree in the African American community. We, at Borland Groover, strongly endorse the recommendation of the American College of Gastroenterology and would encourage all average risk African Americans to begin CRC screening at the age of 45.


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