title: Immunohistochemical analysis of tumour regression grade for rectal cancer after neoadjuvant chemoradiotherapy.
abstract: OBJECTIVE
  Tumour regression grade (TRG) as defined by Rödel et al. has been used as an independent prognostic factor for rectal carcinoma after preoperative treatment by chemoradiotherapy (CRT). Determination of TRG 2 and 3, semiquantitatively defined as more or less than 50% tumour regression, respectively, does not appear to correlate with prognosis. The purpose of this study was to find an immunohistochemical pattern to permit improved stratification of intermediate responders defined by disease free (DFS) and overall survival (OS).
  
  
  METHODS
  Immunohistochemistry of EGFR (epidermal growth factor receptor), VEGF (vascular endothelial growth factor), CD133 antibody, p53 antibody and Ki67 antibody was evaluated using tissue microarrays (TMA) on post-treatment surgical specimens from 88 patients. CD133 expression was confirmed in the whole section when available.
  
  
  RESULTS
  At a median follow-up of 40 months, TRG was found to be an independent predictor of DFS (P = 0.05) and OS (P = 0.001) but no differences were found between TRG 2 and 3 in terms of DFS (P = 0.74) or OS (P = 0.41). The results of TMA showed an immunohistochemically poor prognostic profile for intermediate responders configured by negativity of CD133 expression. However, when examining CD133 expression in the whole section, there was an intermediate correlation with TMA and the prognostic significance was lost.
  
  
  CONCLUSIONS
  The results did not confirm the value of immunohistochemistry in predicting the prognosis of patients with rectal cancer following neoadjuvant chemoradiotherapy. This questions the accuracy of TMA in detecting CD133 expression in this setting.
authors: Service of Medical Oncology, La Paz University Hospital, Madrid, Spain. victor.mgarc@gmail.com
authors: V Moreno
authors: VM
authors: García
authors: J F
authors: JF
authors: Batlle
authors: E
authors: E
authors: Casado
authors: E
authors: E
authors: Burgos
authors: J
authors: J
authors: de Castro
authors: C
authors: C
authors: Belda
authors: J
authors: J
authors: Barriuso
authors: J J
authors: JJ
authors: Sánchez
authors: M Á
authors: MÁ
authors: García-Cabezas
authors: M
authors: M
authors: González-Barón
authors: P
authors: P
authors: Cejas
mesh_terms: D000071916:AC133 Antigen; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000912:Antibodies, Neoplasm / Q000032:analysis*; D015703:Antigens, CD / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis*; D002277:Carcinoma / Q000276:immunology / Q000473:pathology* / Q000628:therapy; D059248:Chemoradiotherapy; D018572:Disease-Free Survival; D066246:ErbB Receptors / Q000032:analysis; D005260:Female; D006023:Glycoproteins / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D019394:Ki-67 Antigen / Q000032:analysis; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D060787:Neoplasm Grading; D010455:Peptides / Q000032:analysis; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012004:Rectal Neoplasms / Q000276:immunology / Q000473:pathology* / Q000628:therapy; D012074:Remission Induction; D012189:Retrospective Studies; D046888:Tissue Array Analysis; D016159:Tumor Suppressor Protein p53 / Q000032:analysis; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis
chemical_list: D000071916:AC133 Antigen; D000912:Antibodies, Neoplasm; D015703:Antigens, CD; D014408:Biomarkers, Tumor; D006023:Glycoproteins; D019394:Ki-67 Antigen; C000606023:PROM1 protein, human; D010455:Peptides; D016159:Tumor Suppressor Protein p53; D042461:Vascular Endothelial Growth Factor A; D066246:ErbB Receptors