Inheritance of cancer of the stomach and large intestine in man.

Abstract

Families of 167 patients with gastric cancer and of 145 patients with cancer of the large intestine were studied to ascertain (1) whether there was a genetic basis for these cancers, (2) whether any genetic basis found was common for the two types of cancer, and (3) whether there was any evidence of the relative roles of genetic and environmental factors. Gastric cancer was found significantly more often in the relatives of index cases with gastric cancer than in the general population, but cancer of the large intestine was not. Similarly, cancer of the large intestine was found significantly more often in relatives of index cases with cancer of the large intestine than in the general population, but gastric cancer was not. This indicated that both types of cancer had specific factors for induction that did not influence the development of the other type. Husbands and wives were not affected with gastric cancer more often than would be expected on the basis of random distribution. Parent and child, and two sibs, were affected, if one showed the disease, with significantly greater frequency than would be expected on the basis of random distribution. These facts indicate that the basis for the increased frequency probably lies in the genetic similarity between the members of the affected pairs, rather than in the environmental similarity. Biased ascertainment cannot be advanced for this familial similarity, because the same relationships hold for families in which the index case was not chosen because of gastric cancer as in those families in which the index case had gastric cancer. No simple genetic pattern of inheritance exists, particularly in families with gastric cancer and in those families with cancer of the large intestine, in which there is no multiple polyposis, so that the genetic basis for both cancer of the stomach and large intestine is very probably polygenic. This study did not show any common environmental factor in the history of the patients.