title: The use of P63 immunohistochemistry for the identification of squamous cell carcinoma of the lung.
abstract: BACKGROUND
  While some targeted agents should not be used in squamous cell carcinomas (SCCs), other agents might preferably target SCCs. In a previous microarray study, one of the top differentially expressed genes between adenocarcinomas (ACs) and SCCs is P63. It is a well-known marker of squamous differentiation, but surprisingly, its expression is not widely used for this purpose. Our goals in this study were (1) to further confirm our microarray data, (2) to analize the value of P63 immunohistochemistry (IHC) in reducing the number of large cell carcinoma (LCC) diagnoses in surgical specimens, and (3) to investigate the potential of P63 IHC to minimize the proportion of "carcinoma NOS (not otherwise specified)" in a prospective series of small tumor samples.
  
  
  METHODS
  With these goals in mind, we studied (1) a tissue-microarray comprising 33 ACs and 99 SCCs on which we performed P63 IHC, (2) a series of 20 surgically resected LCCs studied for P63 and TTF-1 IHC, and (3) a prospective cohort of 66 small thoracic samples, including 32 carcinoma NOS, that were further classified by the result of P63 and TTF-1 IHC.
  
  
  RESULTS
  The results in the three independent cohorts were as follows: (1) P63 IHC was differentially expressed in SCCs when compared to ACs (p<0.0001); (2) half of the 20 (50%) LCCs were positive for P63 and were reclassified as SCCs; and (3) all P63 positive cases (34%) were diagnosed as SCCs.
  
  
  CONCLUSIONS
  P63 IHC is useful for the identification of lung SCCs.
authors.affiliation: Laboratorio de Dianas Terapéuticas, Centro Integral Oncológico Clara Campal, Hospital Universitario Madrid Sanchinarro, Universidad San Pablo-CEU, Madrid, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Conde
authors.forename: Bárbara
authors.initials: B
authors.lastname: Angulo
authors.forename: Pilar
authors.initials: P
authors.lastname: Redondo
authors.forename: Oscar
authors.initials: O
authors.lastname: Toldos
authors.forename: Elena
authors.initials: E
authors.lastname: García-García
authors.forename: Ana
authors.initials: A
authors.lastname: Suárez-Gauthier
authors.forename: Belén
authors.initials: B
authors.lastname: Rubio-Viqueira
authors.forename: Carmen
authors.initials: C
authors.lastname: Marrón
authors.forename: Ricardo
authors.initials: R
authors.lastname: García-Luján
authors.forename: Montse
authors.initials: M
authors.lastname: Sánchez-Céspedes
authors.forename: Angel
authors.initials: A
authors.lastname: López-Encuentra
authors.forename: Luis
authors.initials: L
authors.lastname: Paz-Ares
authors.forename: Fernando
authors.initials: F
authors.lastname: López-Ríos
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D008565:Membrane Proteins / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D011446:Prospective Studies; D015203:Reproducibility of Results; D014157:Transcription Factors
chemical_list: D014408:Biomarkers, Tumor; C081876:CKAP4 protein, human; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; C504003:TTF1 protein, human; D014157:Transcription Factors
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