Utility of CT colonography and/or PET-CT preoperatively in obstructing left-sided colorectal cancers - a systematic...

15-20% of patients present with near obstructing left-sided colorectal cancer. CT colonography (CTC) or PET-CT has been used to detect synchronous lesions, which may alter preoperative planning of colonic resection. We aim to synthesize the usefulness of CT colonography and/or PET-CT in detecting synchronous proximal colon carcinomas in patients who have undergone an incomplete colonoscopy due to a stenosing or obstructing distal colorectal cancer.

A systematic review was performed by searching the databases up to December 2021. Data collected included demographics of the study population, rate of detection of synchronous carcinomas and impact on management of detection of synchronous carcinomas.

A total of 22 studies were included: 17 studies focused on CTC, 3 on PET-CT, and 2 integrated PET-CT with CTC; 2855 patients were included; 53% of patients were male, and 47% were female. All studies reported detection of synchronous proximal colorectal carcinomas using CTC, PET-CT or CTC, and PET-CT combined. CTC detected synchronous carcinomas in 0.2-12.2% of patients. PET-CT was useful in detecting synchronous carcinomas in 4.05-23% of patients. Integrated PET-CT and CTC detected synchronous carcinomas in 2-15% of patients. The surgical plan was changed in 2.4-14.3% of patients after the use of CTC. One PET-CT study reported a change in management in 13.5%. No complication was reported by the use of CTC.

CTC is an effective and useful adjunct to colonoscopy in assessing the proximal colon when colonoscopy fails to do so. However, more evidence is needed with the use of PET-CT for this patient population.