• Chemoprevention
• colorectal cancer
• familial adenomatous polyposis

In this issue of Gut, West et al1 report positive results of a chemoprevention trial in British subjects with familial adenonomatous polyposis (FAP) (see page 918).

There is a long history of use of natural products in FAP and other adenoma prevention trials.2 4 In most cases the rationale seems predicated on notions of likely safety and acceptability, as well as hoped-for efficacy. Moreover, since FAP is an uncommon disease, the greater significance of any positive FAP trial seems to be in the potential for carrying over the experience gained from a relatively easy-to-conduct FAP trial to the testing of the same agent(s) in the much larger population of subjects with non-familial polyps. Put another way, if an agent such as fish oil can actually regress adenomas in FAP, then it may well hold promise in sporadic adenoma patients.

There are both opportunities and challenges in conducting chemoprevention trials in FAP. First, while FAP is a great human model for human ‘adenomagenesis’ and colorectal carcinogenesis, it must be borne in mind that regression of adenomas is not the same as prevention of adenomas. In FAP, sulindac was shown to regress existing adenomas but not to prevent initial ones.5 6 Thus, the stage of disease may matter.

Second, the limited sample sizes and duration of treatment in FAP trials may fail to demonstrate other problems. The experience with COX2 inhibitors7 8 is instrumental here. Because several trials showed …