Complete response after neoadjuvant therapy in rectal cancer: to operate or not to operate?

Evidence exists to support both surgical and nonoperative observational approaches to the management of patients with distal rectal cancer who achieve a complete response following neoadjuvant chemoradiotherapy (CRT). This article summarizes findings from key studies on management strategies for complete pathologic and clinical responders after neoadjuvant CRT for rectal cancer.

A comprehensive literature review was undertaken comparing complete responders to neoadjuvant CRT who underwent surgical procedures or nonoperative observation.

The sensitivity and specificity of clinical assessment tools following neoadjuvant CRT are generally low. Endoscopic ultrasound and MRI are widely used for rectal cancer staging; PET/CT is applied for detecting residual cancer, although limitations exist in assessing mesorectal disease. In patients with rectal cancer who receive neoadjuvant CRT, rates of complete pathologic response vary from 5 to 44%. Rates of nodal disease in patients with complete pathologic response vary from 0 to 15%. In patients with stage 0 rectal cancer, excellent long-term oncologic results have been reported for both surgical resection and nonoperative observation; therefore, some authors consider that surgical resection may result in unnecessary morbidity. Whereas neoadjuvant CRT followed by total mesorectal excision (TME) reduces local recurrence and improves 5-year survival, TME is associated with significant morbidity and suboptimal functional results.

Informed consent in patients with distal rectal cancer who achieve a complete response to neoadjuvant CRT must address both the potential risks of recurrence following nonoperative observation and the increased risks of postoperative morbidity and compromised function following extirpative surgery.