The purpose of this report is to present the descriptive epidemiology of colorectal cancer using the most recent data available to highlight two characteristics of the disease. First is the great variation which takes place in the frequency of this disease over geographic areas of all sizes. Colorectal cancer is common in most countries of North America and Europe, is rare in Asia and is particularly uncommon in Africa. Internationally, the variation in colon cancer is 60-fold, and within Europe there is a 4-fold difference in the incidence of colon cancer between areas with the highest and lowest rates. For cancer of the rectum, variation internationally is 18-fold and within Europe it is 3-fold. Within the United Kingdom, colon cancer is uniformly higher in the 5 Scottish Cancer Registry Regions than in their counterparts in England and Wales. Even within Scotland there is a 4-fold range of colon cancer incidence in rates, with the North and South clearly demarcated by a striking difference in colon cancer incidence in both sexes. Secondly, examination of international mortality rates for colorectal cancer demonstrates remarkable differences in trends over time between countries. In countries where colorectal cancer mortality rates were initially low, rates have increased substantially. In many countries where rates circa 1950 were moderately high, they have increased slightly or become stabilized. However, in countries such as Scotland, Canada, England and Wales and the United States, where rates were initially high, there have been gradual falls in mortality over time.

A case-control study of the role of diet in the etiology of breast cancer was conducted in Athens, Greece. There are reasons to believe that the diet of the Greek population is characterized by greater heterogeneity than that in most countries where such studies have been undertaken. The case series consisted of 120 consecutive patients with histologically confirmed breast cancer admitted to either of two teaching hospitals over a 12-month period. The controls were 120 patients admitted to a teaching hospital for trauma and orthopedic conditions during the same period. Dietary histories concerning the frequency of consumption of 120 foods and drinks were obtained by interview. Cases reported significantly less frequent consumption of vegetables as a group and, within that group, specifically of cucumber, lettuce and raw carrot. After adjustment for potential external confounding variables and for confounding between food categories, the odds ratio for persons in the highest quintile of vegetable consumers, relative to those in the lowest quintile, was 0.09 with 95% confidence limits 0.03-0.30. That is to say, the lowest quintile of vegetable consumers had about 10 times the breast cancer risk of the highest quintile. For a score based on consumption of only the 3 specified salad items the odds ratio over the extreme quartiles was 0.12 (0.05-0.32). There was no association with consumption of fats and oils, alcohol or coffee, and no significant association with any other major food category (including alcohol and coffee) after adjustment for confounding variables.

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