title: EGFR protein expression using a specific intracellular domain antibody and PTEN and clinical outcomes in squamous cell lung cancer patients with EGFR-tyrosine kinase inhibitor therapy.
abstract: OBJECTIVE
  The aim of this research was to examine the molecular and clinical features that are related with EGFR-tyrosine kinase inhibitor (EGFR-TKI) efficacy in previously treated patients with squamous cell carcinoma of the lung (SCCL).
  
  
  METHODS
  This retrospective study included 67 SCCL patients with obtainable lung cancer tissue and records on EGFR-TKI treatment response and survival. EGFR protein expression in lung cancer tissue was measured by immunohistochemistry with a specific antibody that recognizes the intracellular domain (ID) of EGFR. PTEN expression in lung cancer tissue was also evaluated with immunohistochemistry. PI3KCA gene amplification was detected by quantitative real-time polymerase chain reaction, and FGFR1 amplification was assessed by fluorescent in situ hybridization.
  
  
  RESULTS
  EGFR ID expression (hazard ratio [HR] 0.53, P=0.022) and Eastern Cooperative Oncology Group (ECOG) performance status (PS) (HR 0.43, P=0.022) were significantly related with progression-free survival following EGFR-TKIs treatment. PTEN expression (HR 0.52, P=0.025) was significantly related to overall survival. The group of EGFR-positive or PTEN-positive patients with ECOG PS of 0 or 1 had better clinical outcomes than patients who were EGFR-negative and PTEN-negative or who had poor ECOG PS with longer median progression-free survival (2.1 vs 1.0 months, P=0.05) and overall survival (6.2 vs 2.1 months, P=0.05).
  
  
  CONCLUSIONS
  EGFR expression using an ID-specific antibody and PTEN protein expression may be used to identify SCCL patients who might benefit from EGFR-TKI treatment.
authors: Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam; Division of Medical Oncology, Department of Internal Medicine, International St Mary's Hospital, College of Medicine, Catholic Kwandong University, Incheon.
authors: Hyun
authors: H
authors: Chang
authors: Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam; Department of Internal Medicine, CHA Bundang Medical Center, CHA University, Seongnam, Republic of Korea.
authors: Jisu
authors: J
authors: Oh
authors: Department of Pathology, Yanbian University Hospital, Yanji, People's Republic of China.
authors: Xianglan
authors: X
authors: Zhang
authors: Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam.
authors: Yu Jung
authors: YJ
authors: Kim
authors: Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam.
authors: Jae Ho
authors: JH
authors: Lee
authors: Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam.
authors: Choon-Taek
authors: CT
authors: Lee
authors: Department of Pathology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
authors: Jin-Haeng
authors: JH
authors: Chung
authors: Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam.
authors: Jong-Seok
authors: JS
authors: Lee
keywords: EGFR; PTEN; intracellular domain; lung; squamous cell carcinoma; tyrosine kinase inhibitor