Colorectal carcinoma evaluation with CT: preoperative staging and detection of postoperative recurrence.

CT was performed prior to surgery in 103 patients with colorectal carcinoma to assess its value in staging the tumor. Preoperative IBD scans had sensitivities and specificities of 72.7% and 98.9% in detection of liver metastases, 25.9% and 96% in detection of lymph node metastases, and 61.2% and 80.6% in detection of local extension. Compared with the Duke's classification, CT correctly staged only 47.5% of patients: 16.6% were upstaged, and 83.3% were downstaged. Recurrent tumors developed in 11 of 67 patients followed for more than 24 months. CT depicted recurrence in six patients scanned prior to 12 months. Routine scans obtained at 12 months depicted unsuspected tumor recurrence in three of four patients with proved recurrent disease (one patient with pulmonary metastases did not undergo CT). This study indicates that because of the poor accuracy of CT in preoperative local staging of colorectal carcinoma, it has virtually no useful clinical role in this regard. However, preoperative CT evaluation of the liver can be useful. Routine postoperative CT, combined with fine-needle aspiration biopsy, is useful for detection of recurrent tumor.