Four out of every 10 people who should be tested for colorectal cancer are not being screened within the suggested timeframe, according to the March 14 issue of the Morbidity and Mortality Weekly Report from the U.S. Centers for Disease Control and Prevention (CDC).

Guidelines suggest that people 50 and older should have a fecal occult blood test every year, a sigmoidoscopy or double-contrast barium enema every five years, and a colonoscopy every 10 years, the CDC noted.

The agency said that an analysis of three years of state-based health surveys suggests that the rate of screening in that age group increased steadily from 2002 through 2006—from 53.9 percent in 2002 to 56.8 percent in 2004 and 60.8 percent in 2006.

However, three Behavioral Risk Factor Surveillance System surveys show a declining use of the fecal occult blood test as well as disparities along racial, educational and economic lines.

The CDC found that in 2006:

• More men than women were screened, although the difference was not statistically significant.
• People 65 and older reported being screened more often than those 50 to 59 -- 69.3 percent vs. 54.7 percent.
• 62.9 percent of whites and 59 percent of blacks reported being screened, compared with only 47.2 percent of Hispanics.
• 68.7 percent of those with a college degree reported being screened, compared with 62.6 percent of those with some college or technical school, 56.7 percent for high school graduates, and 45.5 percent for those without a high school diploma.
• If annual household income was $75,000 or greater, 70.4 percent of respondents said they had been screened, compared with 67.2 percent for those in the $50,000 to $74,999 bracket; 62 percent of those earning $35,000 to $49,999; 53.9 percent for those getting $15,000 to $34,999; and 48.4 percent for those earning less than $15,000 a year.
• 63 percent of those who had health insurance said they had been screened, compared with 36.7 percent of those without.
• Over the three survey years, the proportion of respondents who reported never being tested fell steadily, from 34.2 percent in 2002 to 32.2 percent in 2004 and to 29.5 percent in 2006.

The proportion of respondents who reported having had a fecal occult blood test within a year of the survey also fell steadily—from 21.6 percent in 2002 to 18.5 percent in 2004 and to 16.2 percent in 2006. In contrast, the proportion who reported a lower endoscopy procedure within 10 years preceding the survey rose from 44.8 percent in 2002 to 50.1 percent in 2004 and to 55.7 percent in 2006.

The CDC noted that the findings are limited by several factors: They are restricted to people with landline telephones, they are based on self-reports, and the response was low for all three years. The CDC also noted that the surveys make no distinction between sigmoidoscopy and colonoscopy, and simply ask whether a respondent had a "lower endoscopy" within the 10 years preceding the survey.

Survey respondents were also asked if they had a fecal occult blood test within the year preceding the survey. Respondents who answered “yes” to both questions were considered to have been screened according to national guidelines, although the CDC noted that may overstate the degree of use of screening by lumping sigmoidoscopy and colonoscopy together.