title: Prediction of Pathological Complete Response Using Endoscopic Findings and Outcomes of Patients Who Underwent Watchful Waiting After Chemoradiotherapy for Rectal Cancer.
abstract: BACKGROUND
  Nonoperative management for patients with rectal cancer who have achieved a clinical complete response after chemoradiotherapy is becoming increasingly important in recent years. However, the definition of and modality used for patients with clinical complete response differ greatly between institutions, and the role of endoscopic assessment as a nonoperative approach has not been fully investigated.
  
  
  OBJECTIVE
  This study aimed to investigate the ability of endoscopic assessments to predict pathological regression of rectal cancer after chemoradiotherapy and the applicability of these assessments for the watchful waiting approach.
  
  
  METHODS
  This was a retrospective comparative study.
  
  
  METHODS
  This study was conducted at a single referral hospital.
  
  
  METHODS
  A total of 198 patients with rectal cancer underwent preoperative endoscopic assessments after chemoradiotherapy. Of them, 186 patients underwent radical surgery with lymph node dissection.
  
  
  METHODS
  The histopathological findings of resected tissues were compared with the preoperative endoscopic findings. Twelve patients refused radical surgery and chose watchful waiting; their outcomes were compared with the outcomes of patients who underwent radical surgery.
  
  
  RESULTS
  The endoscopic criteria correlated well with tumor regression grading. The sensitivity and specificity for a pathological complete response were 65.0% to 87.1% and 39.1% to 78.3%. However, endoscopic assessment could not fully discriminate pathological complete responses, and the outcomes of patients who underwent watchful waiting were considerably poorer than the patients who underwent radical surgery. Eventually, 41.7% of the patients who underwent watchful waiting experienced uncontrollable local failure, and many of these occurrences were observed more than 3 years after chemoradiotherapy.
  
  
  CONCLUSIONS
  The number of the patients treated with the watchful waiting strategy was limited, and the selection was not randomized.
  
  
  CONCLUSIONS
  Although endoscopic assessment after chemoradiotherapy correlated with pathological response, it is unsuitable for surveillance of patients treated via a nonoperative approach. Incorporation of a "watchful waiting" strategy without establishing proper surveillance protocols and salvage strategies might result in poor local control.
authors.affiliation: 1 Department of Surgical Oncology, Faculty of Medicine, The University of Tokyo, Tokyo, Japan 2 Department of Pathology, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Kazushige
authors.initials: K
authors.lastname: Kawai
authors.forename: Soichiro
authors.initials: S
authors.lastname: Ishihara
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nozawa
authors.forename: Keisuke
authors.initials: K
authors.lastname: Hata
authors.forename: Tomomichi
authors.initials: T
authors.lastname: Kiyomatsu
authors.forename: Teppei
authors.initials: T
authors.lastname: Morikawa
authors.forename: Masashi
authors.initials: M
authors.lastname: Fukayama
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D000230:Adenocarcinoma / Q000097:blood / Q000473:pathology / Q000628:therapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D002272:Carcinoembryonic Antigen / Q000097:blood; D059248:Chemoradiotherapy; D003113:Colonoscopy; D013505:Digestive System Surgical Procedures; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage; D006801:Humans; D053208:Kaplan-Meier Estimate; D002955:Leucovorin / Q000008:administration & dosage; D016015:Logistic Models; D008197:Lymph Node Excision; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D016017:Odds Ratio; D011725:Pyridines / Q000008:administration & dosage; D012004:Rectal Neoplasms / Q000097:blood / Q000473:pathology / Q000628:therapy*; D012007:Rectum / Q000601:surgery*; D012074:Remission Induction; D012189:Retrospective Studies; D005641:Tegafur / Q000008:administration & dosage; D016896:Treatment Outcome; D057832:Watchful Waiting
chemical_list: D002272:Carcinoembryonic Antigen; D011725:Pyridines; D005641:Tegafur; D002955:Leucovorin; D005472:Fluorouracil; C104201:gimeracil