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Study finds people residing in poor communities not benefiting from recent drop in colorectal cancer

June 25, 2009

A new study suggests that a drop in colorectal cancer incidence seen nationwide has not occurred among people living in poorer communities, and suggests that barriers to health care may be to blame. The study appears online in the journal Cancer Causes and Control.

Colorectal cancer (CRC) incidence rates have decreased rapidly in the United States since 1998, in large part from the use of endoscopic screening, which can detect and remove polyps before they turn into cancer. However, studies have not fully explored whether all populations, including people of different ages, race/ethnicity, and with differing levels of access to medical care have seen such a drop.

To explore the issue, American Cancer Society epidemiologists examined CRC incidence trends from 1995 to 2004 from 19 cancer registries covering about 53 percent of the U.S. population, comparing incidence rates among different ages, races/ethnicities (whites, African Americans, and Hispanics), and county-level indicators of access to health care: poverty level, supply of primary care physicians (PCPs), insurance rates, and metro vs. non-metro area. They also analyzed changes in rates of screening using endoscopy screening and fecal occult blood stool test (FOBT) for the same set of county-level indicators.

The researchers found that CRC incidence rates decreased significantly across all categories of counties among whites ages 65 and over, who are almost all covered by Medicare, but not among those ages 50 to 64 in counties with high uninsured or poverty rates, fewer PCPs, or in non-metro areas. Among African Americans and Hispanics, incidence rates did not decrease among 50 to 64 year olds in general or among those ages 65 and over residing in counties with high poverty rates, low PCP supply, and non-metro counties (African Americans only). Colorectal endoscopic screening rates increased significantly among whites in both age groups, but not among Hispanics (ages 50 to 64 in general and ages 65 and over residing in high poverty counties) or African Americans residing in counties with higher uninsured rates (ages 50 to 64), low PCP supply, high poverty rates, and non-metro counties (ages 65 and over). FOBT rates remained unchanged during the study time period.

The authors say the study suggests that the decrease in incidence rates among whites 65 and older across all categories of counties may in part reflect an increase in endoscopic screening rates after Medicare expanded reimbursement of selected screening tools in 1998 and 2001. In contrast, the lack of decrease in CRC incidence rates among some population subgroups, including those 50 to 64 year old Hispanics and African Americans in general and whites residing in the most disadvantaged areas, may reflect lack of access to primary care as well as endoscopic screening services.

The authors conclude that that individuals residing in poorer communities with lower access to medical care have not experienced the reduction in CRC incidence rates that have benefited more affluent communities, and that this is likely explained in part by lower utilization of colorectal endoscopic screening even in older populations with coverage through Medicare. They say further research is needed on factors that explain the disparities and potential interventions to address them.

American Cancer Society