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ESGIE DDW: Colonoscopy

Introduction.

Polyps prevalence.

Withdrawal Time

Procedure timing.

Screening & surveillance colonoscopy.

Improved endoscopic techniques.

Introduction

CRC is the second leading cause of Ca−related deaths in the West.

Detection of CRC at an early stage improves the prognosis considerably.

Adenomas are the benign precursors of CRC& their removal results in a lower than expected incidence of CRC.

Polyp prevalence

The effectiveness of colonoscopy in reducing the incidence of CRC depends on adequate visualization / inspection of the colonic mucosa.

Adequate colonoscopy reduces the risk of interval neoplasia & further improves the effectiveness of CRC screening /surveillance programs.

Withdrawal time

Recently WT added to ASGE quality guidelines for colonoscopy.

A WT of > 6 mins is recommended for a -ve colonoscopy.

Measurement/ documentation of WT resulted in a significant increase polyps detection rates.

Continuous recording / feedback are required to maintain adequate WTs.

Procedural timing Significantly more polyps were detected during the first than

during the last colonoscopy of the day.

Screening colonoscopy Screening for CRC recommended by ASGE for average−risk

individuals > 50,but still no consensus on the preferred screening strategy.

Colonoscopy seems to be the most effective screening strategy, but prospective, RCT of colonoscopy screening to reduce the incidence or mortality of CRC are lacking.

The reduction in CRC incidence was 53% with colonoscopy screening, 47% with sigmoidoscopy, 42% with FIT, 46% with FOBT compared to no screening.

Colonoscopy may be the most likely screening strategy to offset the rising costs of new, expensive therapies for CRC.

Screening colonoscopy Colonoscopy screening seems to be feasible /safe& results in a

high detection rate of advanced neoplasia& early carcinoma, suggesting a possible reduction in mortality.

In addition to the effectiveness of a screening strategy, colonoscopy capacity remains an important issue for nationwide CRC screening.

Surveillance intervals The risk for metachronous advanced neoplasia after 5 years was

very low among subjects with a normal baseline colonoscopy.

Earlier surveillance colonoscopy should be offered to subjects with three adenomas or more or with advanced neoplasia at baseline.

A significant association between advanced neoplasia &older age, male sex& between metachronous advanced neoplasia& five or more adenomas at baseline colonoscopy &adenoma size

Importance of risk stratification in patients after polypectomy Besides the number of adenomas& advanced histological features, size& baseline, proximal adenoma were also independent predictors of metachronous advanced neoplasia.

Interval cancer The need for high quality baseline colonoscopy to reduce the

proportion of missed lesions & complete resection of neoplasia to reduce incidence of interval cas.

Improved endoscopic techniques Using standard white−light colonoscopy, a substantial polyp miss

rate of 5±24%.

Polyp detection may improve with novel colonoscopy techniques &optimized visualization methods as NBI.

In one study miss rate for polyps / adenomas is lower with HDNBI than with standard colonoscopy.

In contrast, in a large multicenter RT, no difference in the detection rate of adenomas (32% in the NBI vs. 34% in the standard colonoscopy group).

The detection rates of right−side lesions, advanced adenomas, flat adenomas did not differ between NBI& standard colonoscopy.

Exact role of NBI for the detection of adenoma is not yet proved

NBI shows promise for differentiating between adenomatous &nonadenomatous tissue thus as an instrument for selective polypectomy.

Improved endoscopic techniques Fluorescence colonoscopy increase visibility of adenomas using

endogenous fluorophores or a photoactive marker,using an enema with the photosensitizer precursor hexaminolevulinate (HAL), using a special light source capable of delivering either white or blue excitation light.

A solution to reduce the blind spots might be the use of a wide angle colonoscope instead of standard colonoscope, or third Eye Retroscope (TER), passed down the instrument channel of the colonoscope, provides a retrograde view by turning the tip of the device to look behind folds/ flexures.

TER is promising device to avoid missing polyps due to blind spots behind the folds of the colon.

Value of diminutive & small colonic polyps ACR recommends that diminutive polyps (< 5 mm) should not be

reported on CTC.

Patients with one or two small polyps 6-9mm in size should undergo CTC surveillance after 3 years in lieu of polypectomy at the time of detection.

Standard colonoscopy detected significantly more adenomas smaller than 5mm & 6-9mm in size.

Biopsy/histopathology of small polyps is not cost effective.

Summary: Quality indicators as withdrawal time proven to be effective,

although continuous feedback seems to be necessary.

Procedural timing of colonoscopy was introduced as a new factor influencing polyp yield.

For prevention of CRC, a colonoscopy screening program seems to be the most cost-effective strategy, but colonoscopy capacity is a major issue.

DDW 2008 did not solve the ongoing discussion on the optimal screening strategy.

Surveillance should be targeted at patients at high risk of colorectal neoplasia, including patients with advanced or multiple adenomas.

Summary: In the near future, new endoscopy techniques will be introduced

on a broad basis, increasing the detection of polyps, especially diminutive& small polyps& may improve the endoscopic assessment of polyps &thereby decrease the need for& cost of histological examinations.

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Prepared by: Dr.Mohammad Shaikhani