title: A uniform residual tumor (R) classification: integration of the R classification and the circumferential margin status.
abstract: BACKGROUND
  Since the introduction of the TNM residual tumor (R) classification, the involvement of resection margins has been defined either as a microscopic (R1) or a macroscopic (R2) demonstration of tumor directly at the resection margin ("tumor transected").
  
  
  METHODS
  The recognition of the importance of the circumferential resection margin (CRM) in patients with rectal cancer patients raises the need for an alternative definition of resection margin involvement, namely, the importance of delineating tumor with a minimal distance from the CRM of <or=1 mm (CRM-positive) from tumor directly at the resection margin. The different use of both definitions of resection margin involvement prevents valid comparisons between reports on treatment results.
  
  
  RESULTS
  To avoid confusion by different definitions, the authors proposed including the minimal distance between tumor and resection margin into the current R classification.
  
  
  CONCLUSIONS
  By using the proposed expanded classification, comparisons of new data with previous publications will be possible.
authors.affiliation: Institute of Pathology, University Clinic Leipzig, Leipzig, Germany. wittc@medizin.uni-leipzig.de
authors.forename: Christian
authors.initials: C
authors.lastname: Wittekind
authors.forename: Carolyn
authors.initials: C
authors.lastname: Compton
authors.forename: Phil
authors.initials: P
authors.lastname: Quirke
authors.forename: Iris
authors.initials: I
authors.lastname: Nagtegaal
authors.forename: Susanne
authors.initials: S
authors.lastname: Merkel
authors.forename: Paul
authors.initials: P
authors.lastname: Hermanek
authors.forename: Leslie H
authors.initials: LH
authors.lastname: Sobin
mesh_terms: D006801:Humans; D009367:Neoplasm Staging / Q000379:methods; D018365:Neoplasm, Residual / Q000145:classification* / Q000473:pathology; D012004:Rectal Neoplasms / Q000473:pathology / Q000601:surgery*; D009626:Terminology as Topic