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

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 tomography 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

Computed tomographic colonography: how many and how fast should radiologists report?

OBJECTIVES: To determine if polyp detection at computed tomographic colonography (CTC) is associated with (a) the number of CTC examinations interpreted per day and (b) the length of time spent scrutinising the scan. METHODS: Retrospective observational study from two hospitals. We extracted Radiology Information System data for CTC examinations from Jan 2012 to Dec 2015. For each examination, we determined how many prior CTCs had been interpreted by the reporting radiologist on that day and how long radiologists spent on interpretation. For each radiologist, we calculated their referral rate (proportion deemed positive for 6 mm+ polyp/cancer), positive predictive value (PPV) and endoscopic/surgically proven polyp detection rate (PDR). We also calculated the mean time each radiologist spent interpreting normal studies ("negative interpretation time"). We used multilevel logistic regression to investigate the relationship between the number of scans reported each day, negative interpretation time and referral rate, PPV and PDR. RESULTS: Five thousand one hundred ninety-one scans were interpreted by seven radiologists; 892 (17.2%) were reported as positive, and 534 (10.3%) had polyps confirmed. Both referral rate and PDR reduced as more CTCs were reported on a given day (p  20 min per case) or for too long (> 4 cases consecutively without a break). • Professional bodies should consider introducing a target minimum interpretation time for CT colonography examinations as a quality marker

Post-imaging colorectal cancer or interval cancer rates after computed tomographic colonography: A systematic review and meta-analysis

Background: CT colonography (CTC) is highly sensitive for colorectal cancer, but “interval” or postimaging colorectal cancer (PICRC) rates (diagnosis of cancer after initial negative CTC) are unknown, as are their underlying causes. Methods: We conducted a systematic review and meta-analysis of post-CTC PICRC rates and causes by searching MEDLINE, EMBASE and the Cochrane Register. We included randomised, cohort, cross-sectional or case-control studies published Jan 1994-Feb 2017, using CTC performed according to international consensus standards with aim of detecting cancer or polyps, and reporting PICRC rates or sufficient data to allow their calculation. Two independent reviewers extracted data from the study reports. We used random-effects meta-analysis to estimate pooled PICRC rates, expressed using (a) total number of cancers and (b) total number of CTC scans as denominators, and (c) per 1000 person-years. Primary study authors provided details of retrospective CTC image review and causes for each PICRC. The study is registered (PROSPERO:CRD42016046838). Findings: 2977 articles were screened and 12 analysed. These reported 19,867 patients (18-96 years; of 11,590 with sex data available, 6532 (56·4%) female) from March 2002-May 2015. At mean 34 months’ follow-up (range: 3 to 128·4 months), CTC detected 643 cancers and 29 PICRCs were diagnosed. The pooled PICRC rate was 4·42 PICRCs/100 cancers detected; 95%CI 3·03-6·42, corresponding to 1·61 PICRCs/1000 CTCs (95%CI 1·11-2·33) or 0·64 PICRCs/1000 person-years (95%CI 0·44-0·92). Heterogeneity was low (I2 =0%). Over half (17/28, 61%) of PICRCs were due to perceptual error and visible in retrospect. Interpretation: The 3-year PICRC rate post-CTC is 4·4%, or 0·64 per 1000 person-years, towards the lower end of range reported for colonoscopy. Most arise from perceptual errors. Radiologist training and quality assurance may help reduce PICRC rates. Funding: St Mark’s Hospital Foundation and the UCL/UCLH Biomedical Research Centre

Post-imaging colorectal cancer or interval cancer rates after CT colonography: a systematic review and meta-analysis

Background CT colonography is highly sensitive for colorectal cancer, but interval or post-imaging colorectal cancer rates (diagnosis of cancer after initial negative CT colonography) are unknown, as are their underlying causes. We did a systematic review and meta-analysis of post-CT colonography and post-imaging colorectal cancer rates and causes to address this gap in understanding. Methods We systematically searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials. We included randomised, cohort, cross-sectional, or case-control studies published between Jan 1, 1994, and Feb 28, 2017, using CT colonography done according to international consensus standards with the aim of detecting cancer or polyps, and reporting post-imaging colorectal cancer rates or sufficient data to allow their calculation. We excluded studies in which all CT colonographies were done because of incomplete colonoscopy or if CT colonography was done with knowledge of colonoscopy findings. We contacted authors of component studies for additional data where necessary for retrospective CT colonography image review and causes for each post-imaging colorectal cancer. Two independent reviewers extracted data from the study reports. Our primary outcome was prevalence of post-imaging colorectal cancer 36 months after CT colonography. We used random-effects meta-analysis to estimate pooled post-imaging colorectal cancer rates, expressed using the total number of cancers and total number of CT colonographies as denominators, and per 1000 person-years. This study is registered with PROSPERO, number CRD42016042437. Findings 2977 articles were screened and 12 studies were eligible for analysis. These studies reported data for 19 867 patients (aged 18–96 years; of 11 590 with sex data available, 6532 [56%] were female) between March, 2002, and May, 2015. At a mean of 34 months' follow-up (range 3–128·4 months), CT colonography detected 643 colorectal cancers. 29 post-imaging colorectal cancers were subsequently diagnosed. The pooled post-imaging colorectal cancer rate was 4·42 (95% CI 3·03–6·42) per 100 cancers detected, corresponding to 1·61 (1·11–2·33) post-imaging colorectal cancers per 1000 CT colonographies or 0·64 (0·44–0·92) post-imaging colorectal cancers per 1000 person-years. Heterogeneity was low (I2=0%). 17 (61%) of 28 post-imaging colorectal cancers were attributable to perceptual error and were visible in retrospect. Interpretation CT colonography does not lead to an excess of post-test cancers relative to colonoscopy within 3–5 years, and the low 5-year post-imaging colorectal cancer rate confirms that the recommended screening interval of 5 years is safe. Since most post-imaging colorectal cancers arise from perceptual errors, radiologist training and quality assurance could help to reduce post-imaging colorectal cancer rates

Minimum standards of pelvic exenterative practice: PelvEx Collaborative guideline

This document outlines the important aspects of caring for patients who have been diagnosed with advanced pelvic cancer. It is primarily aimed at those who are establishing a service that adequately caters to this patient group. The relevant literature has been summarized and an attempt made to simplify the approach to management of these complex cases