ABSTRACT
Cancer of the large bowel is the fourth most common cancer in the world. More than 945,000 colon cancer cases and 492,000 colon cancer-related deaths were reported in the year 2000. Colon cancer is one of the leading causes of cancer death in both men and women in Western countries including the U.S., Canada, Northern and Western Europe, Australia, and New Zealand; however, colon cancer is markedly less frequent in Asia, Africa, and South America.1,2 In the U.S. about 147,000 new cases of this cancer and 57,000 related deaths were estimated for the year 2004.2 Marked international differences in the incidence and mortality of colon cancer and the increase of risk in populations migrating from low-to high-risk areas such as from Japan to the U.S. within one or two generations suggest that environmental factors, specifically dietary habits rather than the genetic factors, play an important role in the etiology of this cancer. It is noteworthy that there is an upward trend in colon cancer risk in Japan, which cannot be attributed to genetic differences.3 Nutritional epidemiologic studies conducted in Japan point to the fact that this upward trend in colon risk has been attributed to westernization of Japanese food habits.4 The failure to control cancer deaths from colorectal cancer and other types of cancer provides the rationale to develop strategies for prevention. The logical approach to control colorectal cancer is to prevent it before it progresses to invasive and metastatic malignancy. Dietary fats have been implicated in the development of several types of cancer including the
cancer of the colon in humans. These observations led to experimental studies in preclinical models designed to assess the effect of types of dietary fat including saturated fat, omega-6 polyunsaturated fatty acids (n-6 PUFAs) and n-3 PUFAs (Figure 23.1).
