ABSTRACT
This chapter shows that relatives of an index case with common colorectal cancer are themselves at an increased risk for cancer, when compared to controls. The cotton-top tamarin provides a unique opportunity for research into the genetic factors that predispose to colon cancer and their interaction with environmental agents. Genetic epidemiology has provided important methodological approaches to understanding genetic factors that predispose to colorectal cancer in humans and the cotton-top tamarin. Genetic susceptibility has been deduced from familial aggregation and the existence of inherited syndromes. Although colorectal cancer occurs in Gardner's syndrome, familial adenomatous polyposis, or cancer family syndrome, and in conditions with a genetic predisposition, such as ulcerative colitis, these diseases account for a small fraction of the total cases of colorectal cancer in humans. The incidence of colorectal cancer in Italy in first-degree relatives was evaluated in a study performed on 100 consecutive patients on whom surgery for colorectal cancer was performed, excluding familial polyposis.
