title: Meta-analysis of colorectal cancer follow-up after potentially curative resection.
abstract: BACKGROUND
  After potentially curative resection of primary colorectal cancer, patients may be monitored by measurement of carcinoembryonic antigen and/or CT to detect asymptomatic metastatic disease earlier.
  
  
  METHODS
  A systematic review and meta-analysis was conducted to find evidence for the clinical effectiveness of monitoring in advancing the diagnosis of recurrence and its effect on survival. MEDLINE (Ovid), Embase, the Cochrane Library, Web of Science and other databases were searched for randomized comparisons of increased intensity monitoring compared with a contemporary standard policy after resection of primary colorectal cancer.
  
  
  RESULTS
  There were 16 randomized comparisons, 11 with published survival data. More intensive monitoring advanced the diagnosis of recurrence by a median of 10 (i.q.r. 5-24) months. In ten of 11 studies the authors reported no demonstrable difference in overall survival. Seven RCTs, published from 1995 to 2016, randomly assigned 3325 patients to a monitoring protocol made more intensive by introducing new methods or increasing the frequency of existing follow-up protocols versus less invasive monitoring. No detectable difference in overall survival was associated with more intensive monitoring protocols (hazard ratio 0·98, 95 per cent c.i. 0·87 to 1·11).
  
  
  CONCLUSIONS
  Based on pooled data from randomized trials published from 1995 to 2016, the anticipated survival benefit from surgical treatment resulting from earlier detection of metastases has not been achieved.
authors.affiliation: Department of Cardio-Thoracic Surgery, Erasmus University Medical Centre, Rotterdam, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Mokhles
authors.affiliation: Wales Cancer Trials Unit, Cardiff University, Cardiff, UK.
authors.forename: F
authors.initials: F
authors.lastname: Macbeth
authors.affiliation: Medical Research Council Biostatistics Unit, Institute of Public Health, University of Cambridge, Cambridge, UK.
authors.forename: V
authors.initials: V
authors.lastname: Farewell
authors.affiliation: Division of Surgery and Cancer, and Imperial College Trials Unit, Imperial College London, London, UK.
authors.forename: F
authors.initials: F
authors.lastname: Fiorentino
authors.affiliation: Surgical and Interventional Trials Unit, Division of Surgery and Interventional Science, Faculty of Medical Sciences, University College London, London, UK.
authors.forename: N R
authors.identifier: http://orcid.org/0000-0001-6496-312X
authors.initials: NR
authors.lastname: Williams
authors.affiliation: Oncology Centre, Hospital Alemão Oswaldo Cruz, Sao Paulo, Brazil.
authors.forename: R N
authors.initials: RN
authors.lastname: Younes
authors.affiliation: Department of Cardio-Thoracic Surgery, Erasmus University Medical Centre, Rotterdam, The Netherlands.
authors.forename: J J M
authors.initials: JJ
authors.lastname: Takkenberg
authors.affiliation: Clinical Operational Research Unit, University College London, London, UK.
authors.forename: T
authors.initials: T
authors.lastname: Treasure
mesh_terms: D000359:Aftercare / Q000379:methods; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality / Q000601:surgery*; D006801:Humans; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging / Q000401:mortality; D016019:Survival Analysis; D016896:Treatment Outcome