The influence of dairy and nondairy calcium on subsite large-bowel cancer risk.

This prospective study assesses the impact of fat and calcium intake on the risk of developing cancer in each large-bowel subsite. The study population is a cohort of Hawaii Japanese men who experience high rates of colon cancer, especially of the sigmoid segment. Total calcium intake is not related to the risk of colon cancer, and separation of calcium into dairy and nondairy sources does not alter the result. There is, however, a significant, monotonic increase in sigmoid colon cancer risk with decreasing total calcium intake. Similar trends are shown for both dairy and nondairy calcium. Dietary calcium is not consumed in large quantities among the Hawaii Japanese, partly because of their limited consumption of milk due to lactose intolerance. If calcium plays a protective role against sigmoid colon cancer, this effect is unlikely to be related to fat intake. Sigmoid colon cancer subjects had lower intakes of fat than other cohort men, and a statistical test for the interaction effect of total calcium and fat intake on colon cancer risk was statistically insignificant (P = 0.2).