Food-group consumption and colon cancer in the Adelaide Case-Control Study. II. Meat, poultry, seafood, dairy foods and eggs.

We conducted a case-control study in Australia, comparing 220 persons with histologically confirmed incident adenocarcinoma of the colon with 438 age- and gender-matched controls. Cases were identified via the South Australian Cancer Registry (1979-80); controls were randomly selected from the electoral roll. All participants completed a 141-item food-frequency questionnaire and were interviewed regarding demographic and other information. Consumption of 8 groups of foods from animal sources was investigated. Odds ratios (OR) for quartiles of consumption were obtained using conditional logistic regression. All analyses were conducted separately for females and males. The most striking finding was a positive association for egg consumption in females, with an unadjusted OR of 2.4 (1.1-5.3) for consumption in the uppermost quartile. The uppermost septile of egg consumption was associated with an unadjusted OR of 6.3 (1.5-26.1) and a dose-response pattern was suggested. Intakes of red meat, liver, seafood, and dairy foods were also weakly positively associated with risk in females. In males, intakes of red meat and poultry were weakly positively associated with risk with unadjusted ORs of 1.5 (0.8-2.8) and 1.4 (0.7-2.6) respectively. The ratio of intake of red meat to poultry and seafood was also positively associated with risk in males, with an unadjusted OR of 1.4 (0.8-2.6). Interpretation of analyses stratified by colon cancer subsite was limited by the low number of subjects in each sub-site stratum, yet the results were somewhat supportive of a stronger risk associated with animal foods in the proximal than in the distal colon. The results for egg consumption suggest a role for cholesterol in the etiology of colon cancer, particularly in proximal cancer for females. Results for vegetable and fruit consumption are presented in a companion report.