The familial factor in adenocarcinoma of the colon may be very important when the disease deveilops on the basis of multiple polyposis of the colon or in a "cancer family." In the average situation, however, the increased risk in the immediate relatives of a patient is relatively low, about two to three times normal.
HE TITLE ASSIGNED THIS PRESENTATION BY T the Organizing Committee was "Heredity and Adenocarcinoma of the Colon." However, the more deeply I got into the literature, the more clear it became that although there is abundant evidence that adenocarcinoma of the colon may be familial, there is little critical evidence that this familial tendency may be ascribed to a gene or genes which specifically predisposes the glandular tissue of the colon to a malignant transformation. Accordingly, we will be on sounder grounds if we couch our discussion in terms of familial factors in the etiology of this condition, recognizing once again that familial is by n o means synonymous with genetic or hereditary.
INHERITED POLYPOSES
It will be convenient in this presentation to consider first a collection of genetic entities in which the end result is a familial tendency to adenocarcinoma, the malignancy developing on the basis of an inherited morphological abnormality. These are, of course, the inherited polyposes, of which there are at least 4 types. Three of these have become the subject of an extensive literature, from which we can cite only some of the more important and more recent papers, where further bibliographies will be found. (See also McKusick.24) T h e 4 types are:
- Classical multiple polyposis of the colon,