Screening rates for colorectal cancer in the United States lag far behind those for breast and cervical cancer, despite research showing that the high mortality rates could be lowered significantly by detecting colorectal cancer at an early stage when it is more treatable. A study in the February 12 Archives of Internal Medicine of nearly 600,000 Medicare recipients aged 65 or older living in Illinois, Florida, and New York shows that women, nonwhites, and people with low income or educational levels were less likely to get a colon screening test than were men, whites, and people with higher incomes and education levels.

Over a 2-year period, 18.3 percent of all men and women in the study group had a colon screening test, although women were less likely to undergo invasive screening tests such as colonoscopy. The frequency of screening by both sexes diminished with age, but more so in women.

Most (89.5 percent) beneficiaries in the study were white; blacks, Hispanics, and all other racial and ethnic groups were aggregated together as nonwhite, and were 48 percent less likely to get any screening test than were white participants. Beneficiaries living in areas with the highest proportion of high school graduates were 52 percent more likely to get screened. In general, living in a zip code with a higher per capita income increased the likelihood of getting screened, though nonwhites in the highest income group were actually less likely to be screened. Whites were more likely to get a colonoscopy as their income increased; nonwhites were not.

"Further research is needed to determine the basis for the observed ongoing disparities to develop interventions to reduce and eliminate these differences," wrote Dr. Ashwin N. Ananthakrishnan from the Medical College of Wisconsin in Milwaukee, lead researcher on the study.