Chemoprevention of colorectal cancer: why all the confusion?Bresalier, Robert SCurrent Opinion in Gastroenterology: January 2008 - Volume 24 - Issue 1 - p 48–50 doi: 10.1097/MOG.0b013e3282f31d36 Large intestine: Edited by Robert S. Bresalier Buy SDC Abstract Author InformationAuthors Article MetricsMetrics Purpose of review Chemoprevention provides an opportunity to complement screening for the prevention of colorectal neoplasia. Findings from prospective randomized trials often conflict with those of observational studies. This review discusses some of the possible reasons based on recent clinical trials. Recent findings A recent prospective randomized trial demonstrates that folic acid supplementation in patients with a previous history of colorectal adenomas does not reduce future colorectal adenoma risk, and may possibly increase the risk of colorectal neoplasia. Summary The results of prospective randomized human trials of chemopreventive agents have in many cases been less impressive or have conflicted with the results of observational studies. Issues to be considered are the timing of the intervention during multistep carcinogenesis, baseline levels in a given individual or population, the complexity of dietary interactions, dose–response effects, and the duration of study. The University of Texas MD Anderson Cancer Center, Houston, Texas, USA Correspondence to Robert S. Bresalier, MD, The University of Texas MD Anderson Cancer Center, 1515 Holocombe Blvd, Houston, TX 77030, USA Tel: +1 713 745 4340; e-mail: email@example.com © 2008 Lippincott Williams & Wilkins, Inc.