Colonic proliferation and colon cancer risk. A review of clinical studies

The purpose of this review is to discuss some of the recent hypotheses regarding the dietary etiology of colorectal cancer. We will review some of the epidemiological background and animal studies that were performed to test these hypotheses. The use of the rectal mucosal proliferation rate as measured by thymidine labelling index as an intermediate endpoint for clinical studies is discussed, including the results of testing these hypotheses using this marker. We believe that all hypotheses must eventually be tested in the human model and that carefully controlled, sequential analyses of each acceptable hypothesis is the most prudent road to understanding the environmental causes of colorectal cancer.