title: How often should we perform surveillance colonoscopy after surgery for colorectal cancer?
abstract: OBJECTIVE
  Surveillance colonoscopy is undertaken after resection of colorectal cancer to detect and treat local recurrence and metachronous lesions, with the aim of improving survival. This study aimed to clarify the current timing of surveillance colonoscopies and evaluate the rates of local recurrence and metachronous tumors.
  
  
  METHODS
  We retrospectively analyzed data from 459 patients who underwent surveillance colonoscopy at our institution after curative resection of colorectal cancer. The number and timing of surveillance colonoscopies, incidence of local recurrence and metachronous lesions, pathological findings of lesions, treatment of lesions, and outcomes were recorded.
  
  
  RESULTS
  The first surveillance colonoscopy was undertaken at 6-18 months after surgery in 73 % of patients. Local recurrence was detected in three cases (0.7 %), all during the first surveillance colonoscopy, which was performed >1 year after surgery. These three patients all underwent additional surgery and were alive 5 years later. Invasive metachronous cancers were detected in six patients (1.3 %) at 18-57 months after surgery, and advanced adenomas were detected in 30 patients.
  
  
  CONCLUSIONS
  Considering the low incidence of postoperative lesions and the timing of lesion detection, reducing the number of surveillance colonoscopies after surgery for colorectal cancer may be appropriate.
authors.affiliation: Endoscopy Division, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo, 104-0045, Japan. tasakamo@ncc.go.jp
authors.forename: Taku
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Takahisa
authors.initials: T
authors.lastname: Matsuda
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakajima
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Saito
mesh_terms: D000368:Aged; D003113:Colonoscopy / Q000706:statistics & numerical data*; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000473:pathology / Q000601:surgery*; D003107:Colorectal Surgery / Q000009:adverse effects; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D016609:Neoplasms, Second Primary / Q000473:pathology; D011159:Population Surveillance; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology; D015995:Prevalence; D013997:Time Factors