Accuracy of computed tomography in staging colon cancer patients.

Abstract

614 Background: Though adjuvant chemotherapy is well-established for treating patients with AJCC Stage III colon cancer, there is growing interest in giving chemotherapy neoadjuvantly for these patients. Since clinical staging to determine eligibility requires accurate preoperative imaging, our objective was to determine whether computed tomography (CT) scans can be used to detect nodal disease in colon cancer patients. Methods: We identified patients with AJCC stage I-III colon cancer who underwent curative resection between 2006 and 2010 at our institution. Patient CT scans were obtained and final radiologic reports were recorded in a database. CT images underwent secondary prospective review by a blinded independent surgeon with the intent to identify mesenteric lymphadenopathy (N+). Clinical staging from the original radiologic report and secondary surgeon review of the CT images were then compared with pathologic staging. Results: Imaging and pathology were available for 67 colon cancer patients. Original radiologic review reported N+ disease in 10 of 67 patients (15%), but final pathology revealed 31 of 67 (46%) patients to be N+. Therefore, radiological review correctly predicted Stage III disease in 10 of 31 (32%) patients. On final pathology, 36 of 67 (54%) patients had no nodal disease (N0). Radiologic reports noted absence of lymphadenopathy in 29 of 67 (43%) patients, thus accurately predicting N0 disease in 29 of 36 (80%) patients. Of 67 studies, 14 (21%) had no mention of lymphadenopathy and were considered N0. Of these 14, 6 were N+ on final pathology. Surgeon review accurately identified N+ disease in 4 of these 6 patients. On surgeon review, sensitivity increased from 32% to 68% while specificity dropped from 80% to 61%, corresponding to a decrease in false negatives from 68% to 32% and an increase in false positives from 20% to 39%. Conclusions: Current clinical staging of colon cancer by CT has low accuracy. However, actively seeking nodal disease improves sensitivity but with minor loss of specificity. Improved radiologic criteria and technology may further increase accuracy in clinical staging of Stage III colon cancer patients who will receive neoadjuvant treatment.