Definitive Chemoradiotherapy ("Watch-and-Wait" Approach).

Preoperative chemoradiotherapy (CRT) followed by total mesorectal excision has been the standard of care for locally advanced patients with rectal cancer. Some patients achieve a pathologic complete response (pCR) to CRT and the oncologic outcomes are particularly favorable in this group. The role of surgery in patients with a pCR is now being questioned as radical rectal resection is associated with significant morbidity and long-term effects on quality of life. In an attempt to better tailor therapy, there is an interest in a "watch-and-wait" approach in patients who have a clinical complete response (cCR) after CRT with the goal of omitting surgery and allowing for organ preservation. However, a cCR does not always indicate a pCR, and improved clinical and imaging modalities are needed to better predict which patients have achieved a pCR and therefore can safely undergo a "watch-and-wait" approach. This article reviews the current data on nonoperative management and on-going controversies associated with this approach.