The incidence of colorectal cancer varies according to race, but little is known about how different races are affected by specific types of the disease.
Proximal colon cancer is the most common type of colon cancer, occurring in the proximal portion of the large intestine closest to the small intestine.
Ananya Das, M.D., analyzed the Surveillance, Epidemiology and End-Results (SEER) database of the National Cancer Institute and identified all patients with confirmed, invasive primary colorectal cancer between 1973 and 2003. Gender, race and sub-site specific, age-adjusted incidence rates were calculated.
Overall colon cancer and proximal colon cancer rates gradually declined during the 30-year period in African Americans and Caucasians and men and women. But since the mid-1990s, African Americans, and African American men in particular, have experienced a significant and consistent rise in proximal colon cancer. It has been proposed that cancers occurring at different sub-sites in the colon may have different underlying causes, and that colonoscopy is a better tool for screening for proximal colon cancer than is flexible sigmoidoscopy. In a colonoscopy, a long flexible lighted tube is inserted into the rectum and slowly guided in to view the entire colon, while in a sigmoidoscopy, only the first third of the colon is viewable.
“These results should be used to plan for screening interventions among the African American population to include complete colonoscopies,” said Dr. Das of the Mayo Clinic Scottsdale in Arizona and senior author of the study. “Further epidemiological research is needed to identify site-specific risk factors for proximal colon cancers.”