Chromoendoscopy of the colon

Precision in detecting colon lesions: A key to effective screening policy but will it improve overall outcomes?

Colonoscopy is the gold standard for the screening and diagnosis of colorectal cancer, resulting in a decrease in the incidence and mortality of colon cancer. However, it has a 21% rate of missed polyps. Several strategies have been devised to increase polyp detection rates and improve their characterization and delimitation. These include chromoendoscopy (CE), the use of other devices such as Endo cuffs, and major advances in endoscopic equipment [high definition, magnification, narrow band imaging, i-scan, flexible spectral imaging color enhancement, texture and color enhancement imaging (TXI), etc.]. In the retrospective study by Hiramatsu et al, they compared white-light imaging with CE, TXI, and CE + TXI to determine which of these strategies allows for better definition and delimitation of polyps. They concluded that employing CE associated with TXI stands out as the most effective method to utilize. It remains to be demonstrated whether these results are extrapolatable to other types of virtual CE. Additionally, further investigation is needed in order to ascertain whether this strategy could lead to a reduction in the recurrence of excised lesions and potentially lower the occurrence of interval cancer.

Optical adjuncts for enhanced colonoscopic diagnosis

BACKGROUND

Optical techniques using previously unexploited properties of light interaction with tissue may be valuable in the detection, diagnosis and staging of colorectal neoplasia.

METHODS

A Medline search (1990 to present) was conducted on optical diagnostics in the detection of colorectal neoplasia. The reference list of each identified article was reviewed for further relevant papers.

RESULTS AND CONCLUSION

Chromoendoscopy is the only optical adjunct to colonoscopy that has been tested in large randomized clinical trials. It improves the detection of small and flat colorectal adenomas, and of neoplasia in chronic ulcerative colitis and hereditary non-polyposis colorectal cancer. All other techniques are the subject of ongoing research and the practicality of population screening with any of the methods has yet to be established. Optical techniques may, however, permit immediate clinical diagnosis, removing the need for histological analysis. They may also improve the diagnosis of early colonic neoplasia.

Advances in gastrointestinal endoscopic techniques

An increasing number of techniques for endoscopic diagnosis and treatment is being described. Endoscopic surgeons should be familiar with these techniques. Although many of the diagnostic techniques, other than marking, do not have widespread clinical application, the therapeutic techniques that were described in this article are being used successfully in increasing numbers of appropriately selected patients. Additional experience and technologic advances will refine the endoscopic therapy that is available to patients with colorectal diseases.