Detected EGFR Mutation Could Predict Better Outcome of Lung Adenosquamous Carcinoma Patients

Introduction: Epidermal growth factor receptor (EGFR)-mutant adenocarcinomas (ADC) have a better prognosis than EGFR-wild type cancers, but the role of EGFR in adenosquamous carcinoma (ADSC) is still under investigation. Our aim in this study was to evaluate the role of EGFR mutation in the prognostic outcome of advanced ADSC. Methods: We retrospectively reviewed the medical records of 74 patients diagnosed with ADSC from January 2004 to December 2013, and collected data on 260 patients diagnosed with stage IIIB/IV ADC and squamous cell carcinoma (SCC) from July 2011 to June 2012 to further compare progression-free survival (PFS) and overall survival (OS). Results: Seventeen (17/74, 23.0%) ADSC patients underwent EGFR mutation analysis; 8 (47.1%) were wild-type, and 9 (52.9%) were EGFR-mutant. More never-smokers were found in the EGFR-mutant group (9/9, 100%, p=0.029). ADC patients had significantly better PFS with first-line treatment, followed by ADSC and SCC patients (median PFS: 4.39, 3.50, 2.86 months, respectively; log-rank=0.002). There was no significant difference in OS between the ADC, SCC, and ADSC groups. The ADSC EGFR-mutant group had significantly better PFS than the wild-type group (3.75 vs. 0.71 months; log-rank=0.010), but there was no statistical difference in OS between the 2 groups. Conclusion: We found that the prognosis of the ADSC patients was midway between that of the SCC and ADC patients. Furthermore, EGFR-mutant ADSC patients tended to have a better prognosis than those with wild-type ADSC. Our results suggest that to improve ADSC patient survival, we should check for EGFR mutation, especially in never-smokers.