Body weight and colon cancer.

In 1994, there were approximately 160,000 new cases of colon cancer in the United States with 58,000 fatalities, making this form of cancer the second most common cause of cancer deaths. Up to 50% of colon cancers may have a strong inherited factor, but in the remaining cases, diet and lifestyle factors are thought to play essential roles in the carcinogenic process. Various epidemiologic studies have examined the relation between obesity and colon cancer. The largest prospective study of 750,000 men showed that mortality from colorectal cancer was significantly elevated in men who were > or = 40% overweight. No such increase was found in women. Subsequent studies reported conflicting results. Overweight is likely a surrogate. Other risk factors include a high-fat, energy-dense diet; inadequate consumption of fruit and vegetables; and lack of physical activity, which have been associated with a high incidence of colon cancer.