The treatment strategy of locally advanced rectal cancer has evolved drastically in
the last few decades. A watch-and-wait approach in rectal cancer patients after treatment
with neoadjuvant therapy has been widely incorporated in the current clinical practice.
Nonoperative management in patients with a clinical complete response to neoadjuvant
therapy spares the morbidity associated with surgical excision of the rectum and provides
the opportunity for organ preservation. Challenges remain in the absence of methods
to correctly identify patients with a complete response with absolute certainty. This
review provides a comprehensive overview of retrospective and prospective data regarding
baseline and restaging features associated with a complete response. It also summarizes
the utility limitations of the current diagnostic and surveillance modalities. Lastly,
it describes the current understanding of the role of liquid biopsy as well as future
directions, including innovative optical imaging and machine learning.
Keywords
rectal cancer - complete response - neoadjuvant therapy - watch and wait - patient
selection
