Preoperative segmental localization of colorectal carcinoma: CT colonography vs. optical colonoscopy

Adequate preoperative segmental localization of colorectal cancer is important to indicate the right surgical treatment. Preoperative localization has become more important in the era of minimally invasive surgery. The aim of this study was to compare optical colonoscopy (OC) and CT colonography (CTC) with respect to the error rates in the segmental localization of colorectal carcinoma.

A total of 420 patients with histopathologically proven colorectal carcinoma underwent CTC between December 2006 and February 2017. 284 Of these patients underwent surgical resection and had their carcinomas located on CTC report as well as OC report and surgical report. The segmental localization error rates of OC and CTC were compared using surgery as golden standard. McNemar's test was used to evaluate the differences in error rate.

284 Patients with a total of 296 colorectal carcinomas were evaluated. The segmental localization error rate of CTC (39/296, 13.2%) was found to be lower than the segmental localization error rate of OC (64/296, 21.6%) (p < 0.001). Per segment analysis showed that OC had a significantly higher error rate for carcinomas located in the descending colon (60.6% vs. 21.2% [p < 0.001] and cecum(60.0% vs. 23.3% [p = 0.001]). In 9.2% of the patients (26/284), localization based on CTC would lead to a change in surgical plan.

CTC has a lower localization error rate than OC, which is most relevant for tumors located in the descending colon. If there is a doubtful localization on OC, particularly in the left-sided colon, an additional CTC should be performed to choose the best surgical treatment.