Genetics of rectal cancer.

Two operational subdivisions of hereditary colorectal cancer susceptibility are those with and those without premalignant adenomatous colonic polyp expression. In both of these subdivisions, reliable biomarkers of gene carriage would be of value in patient management as we have previously emphasized. Consideration must also be given to the familial (hereditary) occurrence of inflammatory bowel diseases associating with colorectal cancer susceptibility. The occurrence of rectal cancers should therefore alert the physician to investigate the possibility of a significant family medical history in order to fully elucidate the genetic heterogeneity of susceptibility to this disease. Clinicians should also be alert to the possibility of extracolonic malignancies where probable genetic colorectal cancer susceptibility is evident. Whenever possible, all potential biomarkers should be investigated to aid in definition of genetic heterogeneity.