However, rationalising that aspirin offers unwanted side effects (such as irritation to the stomach lining), drug manufacturers are now marketing NSAIDs, such as sulindac and indomethacin, as primary cancer preventatives. But a recent review article reported that "their effects are incomplete and may cause severe toxicity" (Nippon Geka Gakkai Zasshi, 1998; 99: 385-90).
The much larger hope for prevention is in the area of diet and lifestyle (see box below). In the last 20 years, there has been a major shift in attitude by the medical profession towards the idea that environmental factors, and in particular diet, are among the major causes of all cancers. In fact, bowel cancer was the first cancer to be linked specifically to diet after observations by Dr Denis Burkitt in the 1950s suggested a high fibre diet prevented the disease. At first, Burkitt was ridiculed, but the epidemiological evidence concerning the role of diet soon became overwhelming.
Particularly striking was the observation that the Japanese and Chinese have 20 times less colon cancer than Americans, but when they immigrate to the US and start eating more animal fats and protein but less fibre, their rate of colon cancer rises to the national level within a generation. To date, there have been literally thousands of studies exploring the role of diet in colorectal cancer, leading to widespread agreement that dietary factors are the primary cause, accounting for as much as 90 per cent of its incidence (see box below) (Eur J Cancer Prev, 1998; 7: S79-80).
Alternative treatments, continued on pg 10