Higher rates of colorectal cancer incidence and mortality experienced by African-Americans may be driven largely by differences in health care utilization, and less by biology, according to a new study. In a study involving more than 60,000 people who were screened for colorectal cancer, researchers found that blacks and whites were equally likely to need a follow-up colonoscopy after a screening sigmoidoscopy, but blacks were less likely to actually receive the follow-up.