Objective: To investigate the frequency of epidermal growth factor receptor (EGFR) mutations and their correlation with the efficacy of tyrosine kinase inhibitors (EGFR-TKI) in advanced squamous cell lung cancer.
Methods: This retrospective study enrolled 79 patients with advanced squamous cell lung cancer who received EGFR-TKI at Department of Thoracic Medical Oncology in Peking University Cancer Hospital from June 2004 to June 2011. Among them, 67 patients had tissue and/or plasma EGFR exon 19 and 21 mutation detection in order to make an analysis on the relationship between EGFR mutation and the TKI's effect.
Results: The disease control rate (DCR) was 56% in all the patients. The median progression free survival (mPFS) and median overall survival (mOS) was 3.7 months (95%CI: 2.0 - 5.0) and 11.5 months (95%CI: 6.6 - 14.2), respectively. Of the 67 patients who received EGFR mutation detection, there were 31 patients harboring EGFR-mutation, for whom the DCR was 71% (22/31), and mPFS and mOS was 6.3 months (95%CI: 2.2 - 10.0) and 13.5 months (95%CI: 7.3 - 18.6) respectively. 36 patients' EGFR status were wild type, for whom the DCR was 44% (16/36), mPFS and mOS was 2.2 months (95%CI: 1.1 - 4.0) and 6.4 months (95%CI: 4.0 - 12.0). There were 17 patients who received erlotinib and 7 patients who received gefitinib as second or more line treatment. mPFS and mOS were 7.9 months and 15.8 months in the erlotinib group, respectively; and the mPFS and mOS were both 6.3 months in gefitinib group; the difference between the 2 groups did not reach statistical significance. Cox-regression analysis showed that EGFR mutation was significantly correlated with PFS and OS (P < 0.05, respectively). EGFR mutation was significantly correlated with DCR by Chi-square test, P < 0.05.
Conclusions: EGFR mutation was a predictor for advanced squamous cell lung cancer to EGFR-TKI. However, the effect was inferior in advanced squamous cell lung cancer as compared to lung adenocarcinoma. Erlotinib tended to be superior to gefitinib.