Incomplete colonoscopy in patients with occlusive colorectal cancer: usefulness of CT colonography according to tumor location

Abstract

Purpose: We sought to evaluate the clinical usefulness of CT colonography (CTC) after incomplete conventional colonoscopy (CC) for occlusive colorectal cancer (CRC) according to the tumor location.

Materials and methods: Seventy-five patients with occlusive CRC underwent subsequent CTC immediately after incomplete CC. Fifty-nine patients had distal CRC and 16 had proximal colon cancer. Experienced radiologists prospectively analyzed the location, length, and TNM staging of the main tumor. The colorectal polyps in the remaining colorectum and additional extraluminal findings were also recorded. Sixty-seven patients underwent colorectal resection. We retrospectively analyzed the surgical outcome and correlated CTC and CC findings.

Results: The overall accuracies of tumor staging were: T staging, 86%; N staging (nodal positivity), 70% (80%); and intra-abdominal M staging, 94%. Additional colonic polyps were found in 23 patients. Six synchronous carcinomas were detected (9%); three in the proximal colon and three in the distal colon of occlusion. Clinically significant localization errors at CC were noted in 8 patients (12%, 5 proximal colon cancers and 3 distal CRCs) and were corrected by CTC. After CTC, the surgeons modified the initial surgical plan in 11 cases (16%).

Conclusion: In occlusive CRC, CTC is not only useful in the evaluation of the proximal bowel, but can also provide surgeons with accurate information about staging and tumor localization. CTC is recommended when endoscopists encounter occlusive CRC, regardless of tumor location.

Fig. 1

A 39-year-old woman with mid transverse colon cancer. Axial CT scan reveals irregular wall thickening with luminal narrowing of the transverse colon with pericolic fat infiltration (arrow). The visceral peritoneum was not identifiable and no solid organ invasion was visible, which suggested stage T3. However, the pathologic stage of this lesion proved to be pT4 because of tumor invasion into the visceral peritoneum.

Fig. 2

A 44-year-old woman with proven cecal cancer. This occlusive lesion was initially thought to be in the transverse colon by the endoscopist. Three-dimensional surface rendering of the colon (A) and 2-dimensional coronal reformation (B) revealed a large fungating mass (arrows) in the cecum.

Fig. 3

A 45-year-old man with occlusive colon cancer in the splenic flexure (arrows) with a synchronous colon cancer in the mid transverse colon (arrowheads). (A) The virtual double-contrast display demonstrates an annular circumferential mass in the splenic flexure and a synchronous polypoid cancer in the mid transverse colon, proximal to the occlusion. (B) The transverse CT image and (C) endoluminal CT colonographic image clearly shows this synchronous malignant polyp. (D) Surgical extent was modified to an extended left hemicolectomy to include this synchronous lesion, which could not be identified by CC.