CRC is the second leading cause of Carelated 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.
Adenomas( occur in 25% males/ 15% females > 50 ys.
4. 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.
5. 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.
6. Procedural timing
Significantly more polyps were detected during the first than during the last colonoscopy of the day.
7. Screening colonoscopy
Screening for CRC recommended by ASGE for averagerisk individuals > 50.
Colonoscopy seems to be the most effective screening strategy to offset the rising costs of new, expensive therapies for CRC.
The reduction in CRC incidence was 53% with colonoscopy screening, 47% with sigmoidoscopy, 46% with FOBT compared to no screening.
Colonoscopy may be the most likely screening strategy.
8. 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.
Colonoscopy capacity remains an important issue for nationwide CRC screening.
The uptake of screening colonoscopy is low even in western countries with established screening programs.
9. 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.
Advanced neoplasia occurs more in older age, males, multiple adenomas ( five or more) & size at baseline colonoscopy.
Importance of risk stratification in patients after polypectomy:
The number of adenomas.
Advanced histological features
10. 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 cancers.
11. Improved endoscopic techniques:NBI
Using standard whitelight colonoscopy, a substantial polyp miss rate of 524%.
Polyp detection may improve with novel colonoscopy techniques &optimized visualization methods as NBI.
In one study miss rate for polyps / adenomas is lower with NBI than with standard colonoscopy.
In a large multicenter RT, no difference in the detection rate of adenomas (32% in the NBI vs. 34% in the standard colonoscopy).
The detection rates of rightside 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 for selective polypectomy.
12. Improved endoscopic techniques:
Fluorescence colonoscopy increase visibility of adenomas,using an enema with the photosensitizer.
13. Improved endoscopic techniques:
Reduce the blind spots bythe use of a wide angle colonoscope , or third Eye Retroscope (TER), passed down the instrument channel, provides a retrograde view by turning the tip of the device to look behind folds/ flexures , to avoid missing polyps due to blind spots behind the folds of the colon.
14. 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 5-9mm in size.
Biopsy/histopathology of small polyps is not cost effective.
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.
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.
17. Prepared by:Dr.Mohammad Shaikhani www.themegallery.com Thank You !