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Etiology

Women who consumed more animal fat and red meat and less crude fiber had an increased risk for colon cancer

ACP J Club. 1991 Mar-April;114:61. doi:10.7326/ACPJC-1991-114-2-061


Source Citation

Willett WC, Stampfer MJ, Colditz GA, Rosner BA, Speizer FE. Relation of meat, fat, and fiber intake to the risk of colon cancer in a prospective study among women. N Engl J Med. 1990 Dec 13;323:1664-72.


Abstract

Objective

To determine the relation between diet and the incidence of colon cancer among nurses.

Design

Cohort analytic study (Nurses Health Study).

Setting

U.S. community-based study.

Patients

In 1980, 98 464 women (nurses) (aged between 34 and 59 years) returned a questionnaire on risk factors, including diet, for cancer and coronary heart disease. Women were followed by means of mailed questionnaires every 2 years for 6 years. Nurses were excluded from the study for inadequate questionnaire completion, previous cancer other than nonmelanoma skin cancer, or a history of ulcerative colitis or familial polyposis. More than 90% of the 88 751 eligible nurses forming the baseline cohort responded to the follow-up questionnaires.

Assessment of risk factors

Data collected from the 1980 questions on diet were categorized into quintiles of intake of fats, meats, and other nutrients. Body-mass index measured obesity. Potential risk factors were age-adjusted.

Main outcome measures

Invasive adenocarcinoma of the colon was confirmed by pathology reports in 90% of 150 cases. The National Death Index was used to ascertain deaths of nonrespondents. 39 rectal cancers were not included in the analysis.

Main results

150 cases of colon cancer were found. Total energy intake and body-mass index were not related to the risk for colon cancer. After adjustment for total energy intake, women in the highest quintile of intake of animal fats, compared with those in the lowest quintile, had a relative risk for colon cancer of 1.89 (95% CI 1.13 to 3.15, P = 0.01 for trend). Intake of vegetable fat or of animal fat from dairy sources was not related to colon cancer (P = 0.95 and 0.35, respectively). No relation existed with intake of any type of fiber (P > 0.1 for all types). However, women who consumed the most fat and the least crude fiber, compared with those at the other extreme, had an increased risk for colon cancer (relative risk 2.52, CI 1.00 to 6.34). The nurses who consumed the highest ratio of red meat to white meat had a higher relative risk (2.49, CI 1.50 to 4.13, P < 0.001) for colon cancer than those in the lowest quintile.

Conclusion

Nurses who consumed more animal fat and less crude fiber, and a greater proportion of red to white meat, were at increased risk for developing colon cancer during a 6-year follow-up period.

Source of funding: National Institutes of Health.

Address for article reprint: Not stated.


Commentary

Colon cancer is the second most common cause of cancer deaths in the United States. Nutritional factors have long been linked with colon cancer, particularly dietary animal fat (1) and fiber intake (2). Population studies suggest that differences in diet may account for 90% of the variation in the incidence of colon cancer rates (3). Although recommendations regarding diet have been made (4, 5), previous investigations of the relation between diet and colon cancer in individual persons have been inconclusive.

The results of this study are important for clinical application because they verify the role of diet in women with colon cancer. In addition, because colon cancer occurs with equal frequency in men and women, this study may be generalizable to the entire adult population. Physicians can counsel their patients that appropriate dietary practices will decrease their risk for colon cancer. Patients should be encouraged to avoid animal fats, eat more white meat (fish, chicken) than red meat, and eat a diet high in fiber.

Elisabeth A. McKeen, MD
Palm Beach Oncology-HematologyWest Palm Beach, Florida, USA


References

1. Wynder EL, Reddy BS. Dietary fat and colon cancer [Editorial]. J Natl Cancer Inst. 1975;54:7-10.

2. Burkitt DP. Epidemiology of cancer of the colon and rectum. Cancer. 1971;28:3-13.

3. Doll R, Peto R. The causes of cancer: quantitative estimates of avoidable risks of cancers in the United States today. J Natl Cancer Inst. 1981;66:1191-308.

4. Department of Health and Human Services. Report of the Surgeon General on Nutrition and Health. Washington, DC: Government Printing Office; 1988. DHHS PHS publication no. 88-50210.

5. National Research Council. Committee on Diet and Health. Diet and Health: Implications for Reducing Chronic Disease Risk. Washington, DC: National Academy Press; 1989.