Systematic review and meta-analysis of the evidence for flexible sigmoidoscopy as a screening method for the prevention of colorectal cancer

BACKGROUND

Colorectal cancer is a significant cause of death. Removal of precancerous adenomas, and early detection and treatment of cancer, has been shown to reduce the risk of death. The aim of this review and meta-analysis was to determine whether flexible sigmoidoscopy (FS) is an effective population screening method for reducing mortality from colorectal cancer.

METHODS

MEDLINE (1946 to December 2012) and Embase (1980-2012, week 15) were searched for randomized clinical trials in which FS was used to screen non-symptomatic adults from a general population, and FS was compared with either no screening or any other alternative screening methods. Meta-analysis was carried out using a random-effects Mantel-Haenzsel model.

RESULTS

Twenty-four papers met the inclusion criteria, reporting results from 14 trials. Uptake of FS was usually lower than that for stool-based tests, although FS was more effective at detecting advanced adenoma and carcinoma. FS reduced the incidence of colorectal cancer after screening, and long-term mortality from colorectal cancer, compared with no screening in a selected population. Compared with stool-based tests in a general population, FS was associated with fewer interval cancers.

CONCLUSION

FS is efficacious at reducing colorectal cancer mortality compared with no screening. It is more effective at detecting advanced adenoma and carcinoma than stool-based tests. FS may be compromised by poorer uptake. Introduction of FS as a screening method should be done on a pilot basis in populations in which it is not currently used, and close attention should be paid to maximizing uptake. The relative risk of adverse events with FS compared with stool-based tests should be quantified, and its real-world effectiveness evaluated against the most effective stool-based tests.

MR colonography without bowel cleansing or water enema: a pilot study

OBJECTIVES

The value of screening for colorectal cancer has been well demonstrated, and national programmes are being implemented. At present the primary imaging modality is colonoscopy, which has an associated morbidity and mortality. CT colonography (CTC) has been proposed as an alternative, but this is associated with radiation exposure and generally requires bowel preparation. The aim of this pilot study was to assess the feasibility of MR colonography (MRC) without bowel preparation or water enema for the detection of colorectal neoplasia.

METHODS

Patients scheduled for colonoscopy were invited to participate in the study; informed consent was obtained. MRC (with oral barium faecal tagging and colonic air distension) was performed 1-2 weeks before the colonoscopy. Axial T(2) weighted single-shot fast spin-echo (prone and supine) and axial T(1) weighted fast spoiled gradient-recalled (pre- and post-iv gadolinium) supine MRI sequences were performed. The examinations were reported by two gastrointestinal radiologists by consensus. Colonoscopy following standard bowel preparation was performed by a single endoscopist blinded to the MRC results. Significant lesions were defined as polyps or masses >10 mm in diameter.

RESULTS

29 patients were studied. Colonoscopy revealed 25 mass lesions in 13 patients. MRC correctly identified four of the nine lesions >10 mm in diameter (sensitivity 44%; specificity 100%). Although specificity remained high for smaller lesions, sensitivity was poor.

CONCLUSION

This pilot study has demonstrated the feasibility of performing MRC without bowel preparation or water enema. This would seem to be a promising modality for colorectal cancer screening. Larger studies are required to determine the accuracy of this modality for the detection of colorectal neoplasia.

Audit of bowel preparation with Picolax (sodium picosulfate plus magnesium citrate) for colonoscopy

The aim of this study was to assess the quality of bowel preparation for colonoscopy with standard dose Picolax (two sachets administered on the day prior to the procedure, as per the manufacturer's instructions) in a large cohort of patients. A retrospective audit was performed of colonoscopies performed at our institution over a 1-year period. Patients were excluded if standard dose Picolax was not used, if the quality of the bowel preparation was not recorded or if completion of the procedure was not recorded. Of the 619 fully evaluable cases, the quality of the bowel preparation was assessed by the colonoscopist performing the procedure as good in 263 (42.5%), satisfactory in 242 (39.1%) and poor in 114 (18.4%) of the cases. In only 28 (4.5%) cases, poor bowel preparation was the reason cited for an incomplete colonoscopy. There was no difference in the quality of bowel preparation between inpatients and outpatients. In clinical practice, Picolax is an effective bowel preparation for colonoscopy in the vast majority of cases.