title: American Joint Committee on Cancer and College of American Pathologists regression grade: a new prognostic factor in rectal cancer.
abstract: BACKGROUND
  The American Joint Committee on Cancer and the College of American Pathologists provide guidelines for reporting pathologic response to neoadjuvant treatment of rectal cancer. The clinical relevance of these tumor regression grading guidelines is undefined.
  
  
  OBJECTIVE
  This study evaluates the prognostic significance of the American Joint Committee on Cancer/College of American Pathologists regression grading.
  
  
  METHODS
  This is a retrospective cohort study based on data from a prospectively maintained colorectal cancer database. The cohorts were defined by American Joint Committee on Cancer/College of American Pathologists tumor regression grade.
  
  
  METHODS
  This study was performed at a single tertiary referral center.
  
  
  METHODS
  Five hundred thirty-eight patients with primary rectal adenocarcinoma who underwent neoadjuvant therapy between 1992 and 2012 were identified.
  
  
  METHODS
  The primary outcome measures were overall and disease-free survival, cancer-specific mortality, and cumulative recurrence rate.
  
  
  RESULTS
  Five hundred thirty-eight patients were included, 105 of whom (19.5%) were American Joint Committee on Cancer/College of American Pathologists grade 0, 153 patients (28.4%) were grade 1, 181 patients (33.6%) were grade 2, and 99 (18.4%) were grade 3. Kaplan-Meier analysis revealed that American Joint Committee on Cancer/College of American Pathologists grade was associated with significant differences in overall survival (p < 0.001), disease-free survival (p < 0.001), and cumulative recurrence (p < 0.001). No local recurrences were observed in American Joint Committee on Cancer/College of American Pathologists grade 0 patients. Five-year overall survival rates were 89%, 74%, 63%, and 40% (p < 0.001); 5-year disease-free survival rates were 85%, 64%, 54%, and 33% (p < 0.001); and 5-year recurrence rates were 7%, 18%, 25%, and 33% (p <0.001) for American Joint Committee on Cancer/College of American Pathologists grades 0, 1, 2, and 3. After adjusting for significant covariates, including pathologic stage, American Joint Committee on Cancer/College of American Pathologists grade remained an independent predictor of overall survival (p < 0.001), disease-free survival (p < 0.001), and cumulative recurrence (p < 0.001) in Cox regression analyses.
  
  
  CONCLUSIONS
  This was a retrospective study. There was a low local recurrence rate in our population, limiting the sensitivity of recurrence analyses.
  
  
  CONCLUSIONS
  This is the first study to delineate American Joint Committee on Cancer/College of American Pathologists regression grade as an independent oncologic prognostic factor. This information can be used in discussions with patients who have rectal cancer.
authors.affiliation: 1Department of Colorectal Surgery, Digestive Disease Institute, Cleveland Clinic, Cleveland, Ohio 2Department of Anatomic Pathology, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Adam G
authors.initials: AG
authors.lastname: Mace
authors.forename: Rish K
authors.initials: RK
authors.lastname: Pai
authors.forename: Luca
authors.initials: L
authors.lastname: Stocchi
authors.forename: Matthew F
authors.initials: MF
authors.lastname: Kalady
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology* / Q000628:therapy; D005260:Female; D017408:Guidelines as Topic; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011379:Prognosis; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy; D012189:Retrospective Studies; D012955:Societies, Medical; D015996:Survival Rate; D014481:United States