Oncology
Colorectal cancer incidence is low in patients following a colonoscopy

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Abstract

Background/Aims

Colonoscopy has been proven a valuable tool in preventing colorectal cancer in controlled studies; we conducted a longitudinal confirmation study in everyday clinical practice.

Methods

In a retrospective study, we monitored the outcome of patients with a total colonoscopy at our hospital between 1994 and 2007. We analysed the data of in-house follow-up colonoscopies, a national person registry and the morphological tumour registry centralizing all histopathological data at a national level. Patients with a particular colorectal cancer risk were excluded.

Results

8950 patients were included in our study. 2032 (22.7%) patients had at least one colorectal adenoma at index colonoscopy. Adenoma prevalence was significantly higher in men than in women (27.9% vs. 17.4%, p < 0.001) and was increasing with age in both sexes. Patients were followed for a mean of 5.2 years and 19 had invasive colorectal cancer detected over 47,725 person years of follow-up. The incidence rate was 0.40 cases/1000 person years of follow-up (95% confidence interval, 0.25–0.62), and the standardized incidence ratio was 0.37 (95% confidence interval, 0.24–0.58).

Conclusion

Incidence rates of colorectal cancer are low in the follow-up of patients having undergone a total colonoscopy in everyday practice. After standard therapy of colorectal adenomas at colonoscopy, there is little evidence for excess colorectal cancer incidence in this subgroup.

Introduction

Colorectal cancer (CRC) is one of the most frequent cancers worldwide, and the second leading cause of cancer in Luxembourg. Screening and prevention strategies for CRC are major health policy issues.

Evidence that colorectal adenomas progress to adenocarcinomas and that removing adenomatous polyps prevented CRC was provided by the National Polyp Study (NPS) in 1993 [1]. Follow-up intervals after colonoscopic polypectomy were clearly defined for the first time by the same team [2].

A randomized controlled trial of screening colonoscopy, to define the magnitude of CRC incidence and mortality reduction, has never been done due to the estimated length of time, size of the cohort, and cost [3]. Observational studies are one of the tools to gain further insight into the outcomes of screening colonoscopy.

The primary aim of our study was to assess the incidence of CRC during follow-up of patients having undergone total colonoscopy in routine clinical practice.

Section snippets

Methods

In Luxembourg, colonoscopy is recommended for CRC screening in asymptomatic patients starting at age 50 or earlier in patients with a significant family history of adenoma or CRC. Colonoscopy is reimbursed by social security, but there is no organized screening programme.

In this retrospective study, we analysed colonoscopy reports of all patients having undergone total colonoscopy from January 1994 through June 2007. Age range was 18 years and older, with no upper limit of age. Patients with a

Study population

8950 patients were included in our study, 49.4% of whom were female. Mean age was 56.2 years for men and 55.9 years for women (p > 0.05, t-test). Of our study patients, 10.9% were aged 75 years and older. Indications for colonoscopy included symptoms for 43.3%, screening for 30.7% and remained unknown for 26% of the study population. There was a significant difference in age of patients with symptoms (54.8 years) compared to patients coming for screening (57.1 years) (p < 0.001, t-test). Total

Discussion

Colonoscopy is not a perfect screening tool. Potential disadvantages are the inconvenience of bowel preparation, cost, the risks of sedation, perforation, and not identifying neoplasms [4]. In a virtual colonoscopy study, sensitivity of optical colonoscopy for detecting polyps at least 10 mm in diameter was only 87.5% [5]. Rates of new or missed CRC 6–36 months after colonoscopy from 2 to 6% were reported from Canada [6]. Interval cancers after a colonoscopy might result from lesions missed or

Conflicts of interest

None declared.

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