Comparison of CT colonography vs. conventional colonoscopy in mapping the segmental location of colon cancer before surgery

Abstract

Once presence of a colorectal cancer has been diagnosed, a key factor for patient's prognosis in view of surgical intervention is the correct segmental localization and resection of the tumor. The aim of this work was to compare the accuracy of the current gold standard technique, conventional colonoscopy (CC), to computed tomography colonography (CTC) in the segmental localization of tumor. Sixty-five patients (mean age 64; 45 female and 19 male) with colorectal cancer diagnosed at colonoscopy underwent CTC before surgery. In 45 out of 65 cases (69%), patients were referred to CTC after incomplete CC. Reasons were patient intolerance to CC or presence of stenosing cancer, with consistent difficulties in crossing the tract of the colon involved by the lesion. CTC allowed the complete colonic examination in 63/65 cases, since in 2 patients with an obstructing lesion of the sigmoid colon, pneumocolon could not be obtained. However, per patient and per lesion sensitivity of CTC was 100%. Difference from colonoscopy was statistically significant (P < 0.05). In terms of segmental localization of masses, CTC located precisely all lesions, while colonoscopy failed in 16/67 (24%) lesions, though six were missed for incomplete colonoscopy (9%). In the remaining 10/67 (15%) lesions, detected by colonoscopy but incorrectly located, the mismatch occurred in the rectum (n = 3), sigmoid (n = 2), descending (n = 1), transverse (n = 2), ascending colon, and cecum. Agreement between CTC and CC was fair (k value 0.62). Sensitivity, specificity, positive predictive value and negative predictive value of CTC in determining the precise location of colonic masses were respectively 100%, 96%, 85%, and 100%. CT detected hepatic (6/65 patients) and lung metastases (3/65 patients). CT colonography has better performance in the identification of colonic masses (diameter > 3 cm), in the completion of colonic evaluation and in the segmental localization of tumor. CTC should replace colonoscopy for preoperative staging of colorectal cancer.

Accuracy of CT colonography in the preoperative staging of colon cancer: a prospective study of 217 patients

“…We consider these to be more differences of interpretation than true errors. Taking this into account, and in keeping with other studies , the accuracy of CTC is nearly 100% in tumour localization.…”

Endoscopic localization of colorectal cancer: Study of its accuracy and possible error factors

“…The main indication of preoperative CT in colorectal cancer is tumor staging, being less useful for tumor diagnosis and localization (7,8) and with higher accuracy rate than other radiologic procedures as colonography (1,6,19). Quite often, CT can not identify the tumor, particularly with small lesions with published misdiagnosis rates of 32.7% (2).…”

“…Besides endoscopy, other procedures can help in the localization of CRC. The main indication of preoperative colonography are those cases of incomplete colonoscopy due to the presence of an obstructive tumor allowing the examination of colonic segments proximal to the structure, but it has also showed excellent results for the localization of CRC (1,6,19,25).…”

“…Once CRC has been diagnosed, computed tomography (CT) performance is indicated in the preoperative staging. CT findings allow not only tumor staging but also tumor localization in the colon (5)(6)(7)(8).…”

Dual-Energy CT Colonography for Preoperative “One-Stop” Staging in Patients with Colonic Neoplasia

“…Previously, contrast-enhanced CTC has been proposed as an alternative to OC for preoperative staging of CRC patients because of CTC's improved detection of colonic masses, higher rate of full bowel evaluation, and higher accuracy in segmental localization of the tumor, respectively (5,6). The aim of the present study was therefore to evaluate potential additional benefits of CTC performed on a DE scanner (dual-energy CTC [DECTC]) in the preoperative staging of patients with clinically suspected CRC.…”