title: Complete clinical response after neoadjuvant chemoradiation therapy for distal rectal cancer: characterization of clinical and endoscopic findings for standardization.
abstract: BACKGROUND
  Complete tumor regression may develop after neoadjuvant chemoradiation therapy for distal rectal cancer. Studies have suggested that selected patients with complete clinical response may avoid radical surgery and close surveillance may provide good outcomes with no oncologic compromise. However, definition of complete clinical response is often imprecise and may vary between different studies. The aim of this study is to provide a clear definition for a complete clinical response after neoadjuvant chemoradiation therapy in patients with distal rectal cancer in addition to actual endoscopic videos from patients managed nonoperatively.
  
  
  METHODS
  Patients with nonmetastatic distal rectal cancer treated by neoadjuvant chemoradiation therapy, including 50.4 Gy and concomitant 5-fluorouracil and leucovorin, were assessed for tumor response at least 8 weeks after chemoradiation therapy completion. Complete and incomplete clinical responses were defined based on clinical and endoscopic findings. Patients with complete clinical response were not immediately operated on and were closely followed. Early and late endoscopic findings were recorded.
  
  
  RESULTS
  Definition of a complete clinical response should be based on very strict clinical and endoscopic criteria. The finding of any residual superficial ulceration, irregularity, or nodule should prompt surgical attention, including transanal full-thickness excision or even a radical resection with total mesorectal excision. Standard or incisional biopsies should be avoided in this setting. Complete clinical responders should harbor no more than whitening of the mucosa, teleangiectasia with mucosal integrity to be considered for a nonoperative approach. In the presence of these findings, regularly scheduled reassessments may provide a safe alternative to these patients with early detection of recurrent disease.
  
  
  CONCLUSIONS
  Strict definition of the clinical and endoscopic findings of patients experiencing complete clinical response after neoadjuvant chemoradiation therapy may provide a useful tool for the understanding of outcomes of patients managed with no immediate surgery allowing standardization of classifications and comparison between the experiences of different institutions.
authors.affiliation: Department of Gastroenterology, University of São Paulo School of Medicine, São Paulo, Brazil.
authors.forename: Angelita
authors.initials: A
authors.lastname: Habr-Gama
authors.forename: Rodrigo O
authors.initials: RO
authors.lastname: Perez
authors.forename: Gregory
authors.initials: G
authors.lastname: Wynn
authors.forename: John
authors.initials: J
authors.lastname: Marks
authors.forename: Hermann
authors.initials: H
authors.lastname: Kessler
authors.forename: Joaquim
authors.initials: J
authors.lastname: Gama-Rodrigues
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D016099:Endoscopy, Gastrointestinal; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use; D006801:Humans; D002955:Leucovorin / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D011879:Radiotherapy Dosage; D012004:Rectal Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D002955:Leucovorin; D005472:Fluorouracil