The use of computerized tomography scan in the staging and follow-up study of carcinoma of the rectum.

We have reviewed the CT scans of 30 patients who were evaluated for either primary or recurrent carcinoma of the colon and rectum in the pelvis. The results of our experience have shown that pelvic CT scans can provide accurate information regarding the extramural extension of carcinoma of the rectosigmoid undetected by other means. CT scans can detect significant ureteral pathology as accurately as can IVP and have essentially replaced the IVP in the preoperative evaluation of carcinoma of the rectum. Inflammation of the perirectal musculature, either by the effect of the local tumor or secondary to preoperative radiation, can make it difficult to determine if these structures are invaded by tumor. Tumor involvement, however, can be proved using CT localization and percutaneous fine needle aspiration biopsy techniques. During radiation therapy and chemotherapy, CT scans may also assist in treatment planning and may be the most reliable way of observing the objective response of the recurrent tumor in the pelvis. Finally, in the patient in whom the recurrent tumor does not produce abnormally high levels of CEA, the CT scan may be the only method by which the early and treatable recurrence may be detected. It is, therefore, appropriate to recommend that pelvic CT scan be a routine test for every patient who has had abdominoperineal resection or low anterior resection for carcinoma of the rectum and rectosigmoid.