الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The standard treatment protocol for locally advanced rectal cancer is neoadjuvant chemoradiation then total mesorectal excision. However, this combined approach has long term complications such as bowel, urinary, sexual dysfunction, with the possible need for permanent stoma, which negatively impacts the quality of life of these patients.
With the continuous advances in the field of neoadjuvant treatment, about 30% of these patients have pathological complete response after completion of this treatment protocol. This has raised the interest in organ preserving techniques as watch and wait approach and local excision, with the aim of avoiding the substantial morbidities of radical surgery without compromising the oncological outcomes. In this setting clinical complete response has become an intended outcome necessary to adopt these strategies.
Response assessment after neoadjuvant treatment should include digital rectal examination, endoscopy, and radiological examination with magnetic resonance imaging. Unfortunately, none of these tools can precisely diagnose clinical complete response when used individually, and only their combined use may improve their diagnostic accuracy. Also, several studies have investigated different potential predictors of pathological complete response to preselect patients legible for organ preserving strategies. However, there is lack of consensus on these factors and no robust clinical, pathological, serological, or radiological marker of prediction has yet been identified.