title: p27 expression in post-treatment rectal cancer: a potential novel approach for predicting residual nodal disease.
abstract: BACKGROUND
  Expression profiles of p21, p27, p53, Ki-67, and thymidylate synthase may be associated with response to neoadjuvant chemoradiation. The relationship between post-treatment protein expression and regional lymph node involvement has not been fully explored.
  
  
  METHODS
  Tumor cores from 126 rectal cancer patients underwent immunohistochemical analysis for the aforementioned proteins. Staining indices (SIs) using percentage of stained cells and staining intensity were calculated for 10 tumor cores per patient. SI for each marker was compared between node negative and node positive patients.
  
  
  RESULTS
  Twenty-six (20.6%) cancer patients had a pathologic complete response and 37 had inadequate tissue or cancer cells, leaving 63 for analysis. Thirty-seven (58.7%) cancer patients were node negative and 26 (41.3%) were node positive. There was an association between increased p27 SI and nodal positivity (P = .04).
  
  
  CONCLUSIONS
  Increased p27 expression in post-treatment rectal cancer is associated with nodal positivity and may determine which patients are suitable for local excision.
authors.affiliation: Department of Surgery, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
authors.forename: Tobias
authors.initials: T
authors.lastname: Leibold
authors.affiliation: Department of Surgery, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
authors.forename: Vanessa W
authors.initials: VW
authors.lastname: Hui
authors.affiliation: Department of Pathology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
authors.forename: Jinru
authors.initials: J
authors.lastname: Shia
authors.affiliation: Department of Surgery, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
authors.forename: Jeannine A
authors.initials: JA
authors.lastname: Ruby
authors.affiliation: Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
authors.forename: Elyn R
authors.initials: ER
authors.lastname: Riedel
authors.affiliation: Department of Surgery, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA. Electronic address: guillemj@mskcc.org.
authors.forename: José G
authors.initials: JG
authors.lastname: Guillem
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059248:Chemoradiotherapy; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D018365:Neoplasm, Residual / Q000175:diagnosis*; D011379:Prognosis; D018809:Proliferating Cell Nuclear Antigen / Q000096:biosynthesis / Q000378:metabolism*; D012004:Rectal Neoplasms / Q000378:metabolism* / Q000628:therapy*; D046888:Tissue Array Analysis
chemical_list: D018809:Proliferating Cell Nuclear Antigen; C413374:p27 antigen
keywords: Lymph node positivity; Molecular marker; Post-treatment rectal cancer; Tissue microarray