Chemoprevention in colorectal cancer - where we stand and what we have learned from twenty years' experience

Introduction: Colorectal chemoprevention is a strategy aimed at preventing tumour progression before irreversible changes to the proteome are in full progress. Chemoprevention is not a new concept. In fact, medical practitioners since the early 19th century have tried various herbal and medicinal products as methods that could prevent tumours. The current understanding of tumourigenesis and cellular signalling focuses on a more targeted approach and paves the way for better understanding of colorectal chemoprevention. Methods: The online databases PubMed, Medline, Medscape Oncology and Scirrus were searched for articles of relevance. The Keyword involved the following words: "Colorectal Cancer Chemoprevention", "Colorectal Cancer", "Chemoprevention", "Adenoma-Carcinoma Sequence" and "Colorectal Polyps". The search was started from the period of June 1995 until September 2010 inclusive. Results: More than 50 natural and synthetic compounds have been shown to have chemotherapeutic effect but the majority of these agents are still in their early experimental stages and hence far from our subject of discussion. Our discussion will focus on large scale randomised trials on human subjects or established compounds. Within the context of chemoprevention, Non-steroidal anti-inflammatory agents have undergone extensive research and have shown promising results with large scale randomised trials. Additionally, metformin, resveratrol, Histone deacetylase inhibitors, Src kinases as well monoclonal antibodies have shown promising results as well. Conclusion: Colorectal cancer is the fourth most common cancer in the world. In the UK alone the number of cases reported in 2008 was almost 40,000 which make it the third most common tumour nationwide. Curative intent surgery or Colectomy is the treatment of choice for most cases of bowel cancer; however, in a select subpopulation of patients who have been colonoscopically diagnosed to harbour pre-malignant lesions, have a family history of colorectal cancer, or have been genetically diagnosed and treated surgically for colorectal tumours; chemoprevention might play a crucial role in deterring further tumour progression. The very latest studies that are in publication or are just accruing results are giving us encouraging data that might suggest whether mass scale ingestion of a specific medication might deter colorectal tumour progression. (C) 2011 Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. Published by Elsevier Ltd. All rights reserved.