Coffee Consumption and Cancer - ACS Publications - American

Chapter 8

Coffee Consumption and Cancer Andrew Sivak

Downloaded by NORTH CAROLINA STATE UNIV on January 21, 2013 | http://pubs.acs.org Publication Date: January 15, 2000 | doi: 10.1021/bk-2000-0754.ch008

Environmental Health Sciences, P.O. Box 2128, St. Augustine, FL 32085 Coffee consumption markedly reduces the risk for colon cancer. The incidences of most cancers in the United States, except for lung cancer, have not changed over the last several decades. In experimental chronic animal studies, lifetime coffee consumption did not affect the frequencies of tumors in the test animals (rats and mice). Epidemiology studies have shown no association of coffee consumption with cancer at any organ site. The average odds ratio from epidemiology studies for colon cancer and coffee consumption is 0.78. For studies with benign colon adenomas, the average odds ratio is 0.54. These findings are distributed internationally with reduced colon cancer associated with coffee consumption in Europe, Asia and the United States. Possible mechanisms include the effects of antioxidants in blocking mutations and carcinogen metabolism and increases in glutathione in colonic cells.

Beyond the genetic influences, which can be substantial, the major factors influencing the occurrence of cancer in humans seem to be life style factors (Table 1). If one examines the trends of cancer incidences in the United States over the past several decades, it is clear that the trends are not changing substantially, except for lung cancer, for which cigarette smoking is the main cause (Figures 1 and 2) (/). In men, there has been a sharp reduction in the occurrence of stomach cancers, the reasons for which are largely unknown. For women, there is also a reduction in stomach cancers, and also reductions in liver and pancreatic cancers. The occurrences of colon and rectal cancers appear to be stable in both men and women, although there appears to be some reduction in the incidence of the cancers in women over the past several decades (1-3). Because coffee is such a widely consumed beverage, many experimental and epidemiological studies have been carried out to examine the effects of coffee consumption on cancer occurrence. Among the experimental animal studies, at least four separate studies in both mice and rats receiving coffee at amounts far above that which any human would ever experience reveal no excess of tumors in any of the studies (Table II) (4-8). In fact, in one study in rats there was a significant reduction in breast tumors in the animals consuming coffee (8). Several studies have shown that 64

© 2000 American Chemical Society

In Caffeinated Beverages; Parliment, T., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2000.

65 caffeine can inhibit tumor formation in experimental systems with mouse skin tumors induced by ultraviolet light (9) and rat lung tumors with a nicotine-derived carcinogen (10)


Table I. Environmental Contributions to Cancer Mortality Cause Smoking Diet Occupation Alcohol Viruses and parasites Radiation A i r and water pollution

Percent 25-50 10-70(35) 2-8 2-4 1-10 1 1

Adapted from ref. 3.

Table II. Coffee Chronic Animal Carcinogenesis Studies Species Rats C57BL6J Mice Sprague-Dawley Rats

Sprague-Dawley Rats

Test Substance 100% Coffee 100% Coffee 6% in diet, regular and decaffeinated powder 100%, 50%, 25% Coffee

Result No excess tumors No excess tumors No excess tumors

Reference

No excess tumors

(*)

(4) (5) {6,7)

A n examination of the body of epidemiological studies demonstrates that there is little evidence for the increase of cancer associated with coffee consumption at most of the important organ sites (//). An exception to this finding is the repeated observation that the risk of colon cancer is markedly reduced with coffee consumption. These studies have been recently critically reviewed (12). Among the seventeen studies analyzed, all but two showed a substantial reduction in risk of colon cancer as measured by odds ratio. O f these, the case control studies, which would be expected to be the most reliable, showed an average odds ration of 0.72 for colon cancer associated with coffee consumption (Table III). The two studies that showed some elevated risk were cohort studies in special populations of Mormons and Seventh Day Adventists. The distribution of these findings is worldwide indicating no preference for ethnicity (Table IV). The findings have been demonstrated in populations from the United States, Northern Europe (Belgium, Norway, Sweden), Southern Europe (France, Italy, Spain) and Asia (China, Japan). Figure 3 displays the results of the epidemiology studies in graphic fashion.



1. Age-adjusted cancer rates for women, rates per 100,000 women. (Réf. 1)



1930

1940 1950 . . . . . . . . . Esophagus — — — Lung — ™ — Pancreas

1960 1970 1980 Prostate — Colon & rectum Bladder — Leukemia Stomach — Liver

2. Age adjusted cancer rates for men, rates 100,00 men. (Réf. 1)


1990

68 Table III. Colorectal Cancer Study Design Study

Number of studies


A l l Cancer Studies Cohort Studies Case Control (Total) Case Control (Population) Case Control (Hospital) Adenoma Studies

Number of cases 6,192 931 5,251 2,244 3,017 883

17 5 12 6 6 3

Odds Ratio

0.78 (0.66-0.79) 0.97 (0.73-1.29) 0.72 (0.61-0.84) 0.71 (0.53-0.92) 0.74 (0.61-0.90) 0.57 (0.44-0.72)

ρ Value

Coffee Consumption and Cancer - ACS Publications - American

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