Impact of Smoking and Brain Metastasis on Outcomes of Advanced EGFR Mutation Lung Adenocarcinoma Patients Treated with First Line Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors

PLoS One. 2015 May 8;10(5):e0123587. doi: 10.1371/journal.pone.0123587. eCollection 2015.

Abstract

Objectives: This purpose of this study was to examine clinical-pathologic factors--particularly smoking and brain metastases--in EGFR mutation positive (M(+)) lung adenocarcinoma (ADC) to determine their impact on survival in patients treated with first line EGFR TKI.

Methods: A retrospective review of EGFR mutation reflex testing experience for all ADC diagnosed at a tertiary Asian cancer centre from January 2009 to April 2013. Amongst this cohort, patients with advanced EGFR M(+) ADC treated with first line EGFR TKI were identified to determine factors that influence progression free and overall survival.

Results: 444/742 (59.8%) ADC reflex tested for EGFR mutations were EGFR M(+.) Amongst never-smokers (n=468), EGFR M(+) were found in 74.5% of females and 76.3% of males, and amongst ever smokers (n=283), in 53.3% of females and 35.6% of males. Exon 20 mutations were found more commonly amongst heavy smokers (> 50 pack years and > 20 pack years, Pearson's chi square p=0.044, and p=0.038 respectively). 211 patients treated with palliative first line TKI had a median PFS and OS of 9.2 and 19.6 months respectively. 26% of patients had brain metastasis at diagnosis. This was significantly detrimental to overall survival (HR 1.85, CI 1.09-3.16, p=0.024) on multivariate analysis. There was no evidence that smoking status had a significant impact on survival.

Conclusions: The high prevalence of EGFR M(+) in our patient population warrants reflex testing regardless of gender and smoking status. Smoking status and dosage did not impact progression free or overall survival in patients treated with first line EGFR TKI. The presence of brain metastasis at diagnosis negatively impacts overall survival.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / drug therapy*
  • Adenocarcinoma / enzymology
  • Adenocarcinoma / genetics*
  • Adenocarcinoma of Lung
  • Adult
  • Aged
  • Aged, 80 and over
  • Brain Neoplasms / enzymology
  • Brain Neoplasms / genetics
  • Brain Neoplasms / secondary*
  • Cohort Studies
  • DNA Mutational Analysis
  • Demography
  • Disease Progression
  • Disease-Free Survival
  • ErbB Receptors / antagonists & inhibitors
  • ErbB Receptors / genetics*
  • Female
  • Humans
  • Kaplan-Meier Estimate
  • Lung Neoplasms / drug therapy*
  • Lung Neoplasms / enzymology
  • Lung Neoplasms / genetics*
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Mutation / genetics*
  • Neoplasm Staging
  • Protein Kinase Inhibitors / pharmacology
  • Protein Kinase Inhibitors / therapeutic use*
  • Reflex / drug effects
  • Smoking / adverse effects*
  • Treatment Outcome

Substances

  • Protein Kinase Inhibitors
  • ErbB Receptors

Grants and funding

This work is supported in part by a National Medical Research Council Grant (NMRC/1224/2009), National Cancer Centre Research Fund (NRFMP10111-10112). We are also grateful to the Trailblazer Foundation Ltd. and Singapore Millennium Foundation Ltd for their instrumental support to the Lung Cancer Consortium Singapore (NRFTB11122). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.