Colon cancer screening with CT colonography: logistics, cost-effectiveness, efficiency and progress

Abstract

Colorectal cancer (CRC) incidence and mortality can be significantly reduced by population screening. Several different screening methods are currently in use, and this review focuses specifically on the imaging technique computed tomographic colonography (CTC). The challenges and logistics of CTC screening, as well as the importance of test accuracy, uptake, quality assurance and cost-effectiveness will be discussed. With comparable advanced adenoma detection rates to colonoscopy (the most commonly used whole-colon investigation), CTC is a less-invasive alternative, requiring less laxative, and with the potential benefit that it permits assessment of extra colonic structures. Three large-scale European trials have contributed valuable evidence supporting the use of CTC in population screening, and highlight the importance of selecting appropriate clinical management pathways based on initial CTC findings. Future research into CTC-screening will likely focus on radiologist training and CTC quality assurance, with identification of evidence-based key performance indicators that are associated with clinically-relevant outcomes such as the incidence of post-test interval cancers (CRC occurring after a presumed negative CTC). In comparison to other CRC screening techniques, CTC offers a safe and accurate option that is particularly useful when colonoscopy is contraindicated. Forthcoming cost-effectiveness analyses which evaluate referral thresholds, the impact of extra-colonic findings and real-world uptake will provide useful information regarding the feasibility of future CTC population screening.

Figure 1.

Two main pathways contribute to the development of colorectal cancer (CRC), with most sporadic cancers occurring via the adenomatous pathway. Accumulation of genetic mutations leads to the development of cancer from benign, precancerous polyps; if removed, this can prevent CRC from occurring (i.e. reduce incidence). Detection and treatment of early cancer during its asymptomatic phase can improve survival rates (i.e. reduce mortality). Image constructed from elements available from www.somersault1824.com.

Figure 2.

(a) Two-dimensional (2D) axial CTC image depicts a 4 cm saddle-shaped caecal lesion (arrow). (b) Three-dimensional (3D) endoluminal image shows the morphology of the tumour. (c) Corresponding colonoscopy image. The patient underwent right hemicolectomy, with final pathological diagnosis of a moderately differentiated adenocarcinoma, pT3 N0 V0 R0, Duke’s B (TNM 5th edition).