Key Concepts

• A proportion of patients with rectal cancer managed by neoadjuvant chemoradiation may achieve complete disappearance of the primary tumor (complete clinical response) during assessment of response after treatment completion.
• Establishing a complete clinical response requires the combination of clinical, endoscopic, and radiological findings consistent with the absence of residual cancer at the site of the original cancer.
• Patients that achieve a complete clinical response have been considered for organ preservation strategy with strict surveillance and no immediate surgery (Watch and Wait) to avoid the potential morbidity, mortality, requirement for stomas, and functional consequences of a proctectomy.
• Patients that achieve a complete clinical response and are managed by the Watch and Wait strategy have a 25% risk for developing local regrowth of the primary tumor.
• The majority of local regrowths are amenable to successful salvage proctectomy with negative resection margins (R0).
• Patients that achieve a cCR and are managed by Watch and Wait have similar overall survival rates when compared to patients with pCR managed by radical proctectomy. Disease-free survival rates are superior for patients undergoing radical proctectomy due to the 25% risk of local regrowth following WW requiring salvage proctectomy.
• Functional outcomes and quality of life appear to be improved among patients with complete clinical response managed by Watch and Wait when compared to proctectomy.