Can We Predict Which Patients with Rectal Cancer Will Have a Complete Response to Neoadjuvant Therapy?

Abstract 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.