title: Pretherapeutic MRI for decision-making regarding selective neoadjuvant radiochemotherapy for rectal carcinoma: interim analysis of a multicentric prospective observational study.
abstract: OBJECTIVE
  To study the accuracy of different cutoffs for an involved circumferential resection margin (CRM) compared with T and N categories measured by MRI as basis for selective application of neoadjuvant radiochemotherapy (nRCT) in rectal carcinoma.
  
  
  METHODS
  In a prospective multicenter observational study involving 153 primarily operated patients, the preoperative results of MRI with pathohistological findings of resected specimens were compared.
  
  
  RESULTS
  For a cutoff of ≤1 mm for involvement of the CRM, the accuracy of preoperative MRI was 90.9% (139/153). The negative predictive value was 98.5% (134/136). The four participating departments did not differ significantly. For a cutoff of >2 mm and >5 mm, the rates of false-positive findings increased significantly from 5% to 12% and 35% with a decrease in accuracy to 82% and 62%, respectively. In contrast, the accuracy in predicting T (69.3%) and N categories (61.4%) was much lower.
  
  
  CONCLUSIONS
  The indication for nRCT should be based on the determination of the minimal distance of the tumor from mesorectal fascia with a cutoff point of >1 mm as measured by MRI.
authors.affiliation: Department of Surgery at Carl-Thiem-Klinik, Cottbus, Germany.
authors.forename: Henry
authors.initials: H
authors.lastname: Ptok
authors.forename: Reinhard
authors.initials: R
authors.lastname: Ruppert
authors.forename: Joachim
authors.initials: J
authors.lastname: Stassburg
authors.forename: Christoph Andreas
authors.initials: CA
authors.lastname: Maurer
authors.forename: Katja
authors.initials: K
authors.lastname: Oberholzer
authors.forename: Theodor
authors.initials: T
authors.lastname: Junginger
authors.forename: Susanne
authors.initials: S
authors.lastname: Merkel
authors.forename: Paul
authors.initials: P
authors.lastname: Hermanek
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059186:Chemoradiotherapy, Adjuvant / Q000379:methods / Q000706:statistics & numerical data*; D003661:Decision Support Techniques; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods / Q000706:statistics & numerical data; D015995:Prevalence; D011379:Prognosis; D012004:Rectal Neoplasms / Q000453:epidemiology / Q000473:pathology* / Q000628:therapy*; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016896:Treatment Outcome