[Endoscopic response evaluation in gastrointestinal cancers after neoadjuvant chemora- diotherapy]

Neoadjuvant chemoradiotherapy has emerged as the standard treatment for locally advanced rectal cancer, esophageal cancer and gastroesophageal junction cancer which can not only improve the rate of local control but also induce pathological complete response in some patients. For patients who have achieved clinical complete response after neoadjuvant therapy, the watch & wait strategy and organ preservation could reduce unnecessary surgery and minimize the risk of postoperative complications, meanwhile greatly improve patients' quality of life without affecting the oncologic outcome. At present, a variety of methods, including white light endoscopy, endoscopic forceps biopsy, image enhanced endoscopy, endoscopic ultrasound, endoscopic ultrasound guided fine needle aspiration, endoscopic submucosal dissection, artificial intelligence assisted technology, etc., have become important assistance for the evaluation of tumor response after neoadjuvant chemoradiotherapy and have been widely used in clinical practice. This review will briefly introduce the application of the endoscopic approaches mentioned above and some novel endoscopic techniques and developing trends in response evaluation for patients with locally advanced rectal cancer, esophageal cancer and gastroesophageal junction cancer patients receiving neoadjuvant chemoradiotherapy.