title: Neoadjuvant chemotherapy evaluation by MRI volumetry in rectal cancer followed by chemoradiation and total mesorectal excision: Initial experience.
abstract: OBJECTIVE
  To evaluate rectal cancer volumetry in predicting initial neoadjuvant chemotherapy response.
  
  
  METHODS
  Sixteen consecutive patients who underwent neoadjuvant chemotherapy (CX) before chemoradiotherapy (CRT) and surgery were enrolled in this retrospective study. Tumor volume was evaluated at the first magnetic resonance imaging (MRI), after CX and after CRT. Tumor volume regression (TVR) and downstaging were compared with histological results according to Tumor Regression Grade (TRG) to assess CX and CRT response, respectively.
  
  
  RESULTS
  The mean tumor volume was 132 cm(3) ± 166 before and 56 cm(3) ± 71 after CX. TVR after CX was significantly different between patients with poor histologic response (TRG1/2) and those with good histologic response (TRG3/4) (P = 0.001). An optimal cutoff of TVR >68% (area under the curve [AUC]: 0.9, 95% confidence interval [CI]: 0.65-0.98, P = 0.0001) to predict good histology response after CX was assessed by receiver operating characteristic curve. According to previous data and this study, we defined 70% as the best cutoff values according to sensitivity (86%), specificity (100%) of TVR for predicting good histology response. In contradistinction, MRI downstaging was associated with TRG only after CRT (P = 0.04).
  
  
  CONCLUSIONS
  Our pilot study showed that MRI volumetry can predict early histological response after CX and before CRT. MRI volumetry could help the clinician to distinguish early responders in order to aid appropriate individually tailored therapies.
authors.affiliation: MUHC McGill University, Montreal, Canada. stephanienougaret@free.fr
authors.forename: Stephanie
authors.initials: S
authors.lastname: Nougaret
authors.forename: Shinya
authors.initials: S
authors.lastname: Fujii
authors.forename: Helen C
authors.initials: HC
authors.lastname: Addley
authors.forename: Frederic
authors.initials: F
authors.lastname: Bibeau
authors.forename: Himanshu
authors.initials: H
authors.lastname: Pandey
authors.forename: Hisham
authors.initials: H
authors.lastname: Mikhael
authors.forename: Caroline
authors.initials: C
authors.lastname: Reinhold
authors.forename: David
authors.initials: D
authors.lastname: Azria
authors.forename: Philippe
authors.initials: P
authors.lastname: Rouanet
authors.forename: Benoit
authors.initials: B
authors.lastname: Gallix
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D059186:Chemoradiotherapy, Adjuvant / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D011351:Proctoscopy; D011379:Prognosis; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D047368:Tumor Burden