title: Assessment of Clinical Complete Response After Chemoradiation for Rectal Cancer with Digital Rectal Examination, Endoscopy, and MRI: Selection for Organ-Saving Treatment.
abstract: BACKGROUND
  The response to chemoradiotherapy (CRT) for rectal cancer can be assessed by clinical examination, consisting of digital rectal examination (DRE) and endoscopy, and by MRI. A high accuracy is required to select complete response (CR) for organ-preserving treatment. The aim of this study was to evaluate the value of clinical examination (endoscopy with or without biopsy and DRE), T2W-MRI, and diffusion-weighted MRI (DWI) for the detection of CR after CRT.
  
  
  METHODS
  This prospective cohort study in a university hospital recruited 50 patients who underwent clinical assessment (DRE, endoscopy with or without biopsy), T2W-MRI, and DWI at 6-8 weeks after CRT. Confidence levels were used to score the likelihood of CR. The reference standard was histopathology or recurrence-free interval of >12 months in cases of wait-and-see approaches. Diagnostic performance was calculated by area under the receiver operator characteristics curve, with corresponding sensitivities and specificities. Strategies were assessed and compared by use of likelihood ratios.
  
  
  RESULTS
  Seventeen (34 %) of 50 patients had a CR. Areas under the curve were 0.88 (0.78-1.00) for clinical assessment and 0.79 (0.66-0.92) for T2W-MRI and DWI. Combining the modalities led to a posttest probability for predicting a CR of 98 %. Conversely, when all modalities indicated residual tumor, 15 % of patients still experienced CR.
  
  
  CONCLUSIONS
  Clinical assessment after CRT is the single most accurate modality for identification of CR after CRT. Addition of MRI with DWI further improves the diagnostic performance, and the combination can be recommended as the optimal strategy for a safe and accurate selection of CR after CRT.
authors.affiliation: Department of Radiology, Maastricht University Medical Centre, Maastricht, The Netherlands. moniquemaas@live.nl.
authors.forename: Monique
authors.initials: M
authors.lastname: Maas
authors.affiliation: Department of Radiology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Doenja M J
authors.initials: DM
authors.lastname: Lambregts
authors.affiliation: Department of Epidemiology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Patty J
authors.initials: PJ
authors.lastname: Nelemans
authors.affiliation: Department of Radiology, Maastricht University Medical Centre, Maastricht, The Netherlands.|Department of Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Luc A
authors.initials: LA
authors.lastname: Heijnen
authors.affiliation: Department of Radiology, Maastricht University Medical Centre, Maastricht, The Netherlands.|Department of Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Milou H
authors.initials: MH
authors.lastname: Martens
authors.affiliation: Department of Surgery, Laurentius Hospital Roermond, Roermond, The Netherlands.
authors.forename: Jeroen W A
authors.initials: JW
authors.lastname: Leijtens
authors.affiliation: Department of Surgery, Atrium Medical Centre, Heerlen, The Netherlands.
authors.forename: Meindert
authors.initials: M
authors.lastname: Sosef
authors.affiliation: Department of Surgery, Orbis Medical Centre, Sittard, The Netherlands.
authors.forename: Karel W E
authors.initials: KW
authors.lastname: Hulsewé
authors.affiliation: Department of Surgery, Leeuwarden Medical Centre, Leeuwarden, The Netherlands.
authors.forename: Christiaan
authors.initials: C
authors.lastname: Hoff
authors.affiliation: Department of Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Stephanie O
authors.initials: SO
authors.lastname: Breukink
authors.affiliation: Department of Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Laurents
authors.initials: L
authors.lastname: Stassen
authors.affiliation: Department of Radiology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Regina G H
authors.initials: RG
authors.lastname: Beets-Tan
authors.affiliation: Department of Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands. g.beets@mumc.nl.
authors.forename: Geerard L
authors.initials: GL
authors.lastname: Beets
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000601:surgery / Q000628:therapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D059248:Chemoradiotherapy; D038524:Diffusion Magnetic Resonance Imaging; D051517:Digital Rectal Examination; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D059351:Organ Sparing Treatments; D011351:Proctoscopy; D011446:Prospective Studies; D012372:ROC Curve; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000601:surgery / Q000628:therapy*; D012074:Remission Induction; D016896:Treatment Outcome