Elsevier

Clinical Radiology

Volume 58, Issue 11, November 2003, Pages 855-861
Clinical Radiology

Use of Multidetector-row CT Colonography for Detection of Colorectal Neoplasia in Patients Referred via the Department of Health “2-Week-Wait” Initiative

https://doi.org/10.1016/S0009-9260(03)00273-3Get rights and content

Abstract

AIM: Patients referred under the Department of Health 2-week wait initiative with symptoms of colorectal cancer frequently undergo whole-colon examination. We investigated the use of computed tomography (CT) colonography as an alternative to colonoscopy in this scenario.

MATERIALS AND METHODS: Fifty-four consecutive patients, referred via the 2-week wait initiative and scheduled for colonoscopy, consented to undergo multidetector CT colonography immediately before endoscopy. The site and morphology of any polyp or cancer detected by CT was noted and comparison made with subsequent colonoscopy.

RESULTS: Colonoscopy detected polyps or cancer in 29 patients (53.7%). CT colonography prospectively detected 18 of 41 (44%) polyps of 1–5 mm, three of four (75%) polyps of 6–9 mm, four of four (100%) polyps 10 mm or larger, and five of six (83%) cancers. The missed cancer occurred early in the series and was a perceptive error. The overall sensitivity, specificity, positive predictive value and negative predictive value of CT colonography for cancer and polyps 10 mm or greater on a per patient basis were 90, 100, 100 and 98%, respectively. CT detected one renal cancer and one colonic cancer, initially missed due to incomplete colonoscopy.

CONCLUSION: CT colonography is a robust technique for investigation of symptomatic patients. The learning curve must be overcome for optimal performance.

Introduction

In an attempt to prevent delay in the diagnosis and treatment of cancer, the UK government has proposed that “everyone with suspected cancer will be able to see a specialist within 2 weeks of their GP deciding that they need to be seen urgently and requesting an appointment” [1]. This standard is now applicable to all common cancers, including colorectal, the second most common cause of cancer-related death in the UK [2]. On the basis of a comprehensive literature review, the Association of Coloproctology of Great Britain and Ireland devised six symptom complexes estimated to account for up to 90% of patients with colorectal cancer [3], which have been used to identify high-risk patients. However, the relatively low specificity of some symptoms and variability in interpreting these guidelines has meant that many referred patients have no significant colonic abnormality. Indeed, initial experience suggests that only 9–20% of referred patients have colorectal cancer 4, 5, 6.

Most patients referred via the 2-week-wait initiative merit some form of whole-colon investigation, but although colonoscopy remains the most sensitive test, it is expensive, resource intensive [7], time-consuming, and has an associated small, but well recognized morbidity and mortality [8]. Complications related to sedation are increased in the elderly 9, 10, highly relevant as two of the six symptom complexes are specific to patients over 60 years [3]. Furthermore the average national caecal intubation rate may be as low as 57% [11]. Barium enema remains the standard radiological alternative to colonoscopy, but is less sensitive [12]. Computed tomography (CT) colonography is a relatively new technique that has similar advantages of safety, is well tolerated [13], and has reported sensitivity for colonic neoplasia surpassing barium enema and approaching conventional endoscopy 14, 15, 16, 17. We hypothesized that CT colonography might be a practical first-line investigation for those referred under the 2-week-wait initiative and tested this against colonoscopy as the gold standard.

Section snippets

Patients and Methods

Our local ethical review committee approved the study and all participants gave informed written consent. At our institution, all 2-week-wait initiative referrals are faxed by general practitioners to a single dedicated facsimile machine, from which patient details are recorded and outpatient appointments organized. Consecutive patients were directed, if possible, to a single weekly morning colonoscopy list. Between May 2001 and June 2002 a total of 86 “2-week wait” patients were referred for

Results

The mean time spent by patients in the CT suite was 23.2 min (SD 5.3, range 13–33 min) with a mean examination time of 8.8 min (SD 2.6, range 9–17 min). The mean reporting time for CT colonography was 13.9 min (SD 4.1, range 8–30 min). No patient undergoing CT colonography refused subsequent colonoscopy. The mean time for colonoscopy was 24.1 min (SD 8.1, range 14–38 min). Colonoscopy was complete in 49 patients (91%). Reasons for non-completion were obstructing tumour in two patients (sigmoid

Discussion

The prognosis of colorectal cancer is related to the histological stage [21], and it is believed that earlier diagnosis may improve disease specific mortality. Recognizing that waiting times for hospital out-patient appointments were frequently too long [22], the UK government initiated the 2-week-wait standard in an attempt to ensure that patients suspected of having cancer are seen quickly and efficiently. Unfortunately, symptoms of colorectal cancer are non-specific and the majority of

Acknowledgments

This research was supported by a research fellowship from the Royal College of Radiologists, the Wexham Gastrointestinal Trust, and by General Electric Medical Systems, Slough, UK.

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