EGFR mutation in squamous cell carcinoma of lung - Does it carry the same connotation as in adenocarcinomas?

Background

EGFR Tyrosine Kinase Inhibitiors (TKIs) have greatly improved outcomes of EGFR mutation positive Adenocarcinomas of lung. In contrast, the significance of EGFR mutation in metastatic Squamous Cell Carcinoma (SCC) of Lung has been debated. We looked at the outcomes of EGFR mutation positive SCC of lung treated at our centre.

Methods

All patients with metastatic NSCLC treated at our centre from 2010 to 2015 were included for analysis. EGFR kinase domain mutations were determined in all patients with metastatic NSCLC using Taqman based real time PCR. Treatment decisions including the decision to start TKI and the type of TKI (erlotinib or gefitinib) were at the discretion of the treating physicians. Response assessment was done using RECIST 1.1. Progression free survival (PFS) was calculated from date of start of TKI till progression or last follow-up. Overall Survival (OS) was calculated from date of first consultation to date of death or last follow-up.

Results

EGFR mutation was detected in 29 patients with SCC. Median age of the patients was 59 years with 22 males and 7 females. 19 out of the 29 patients received TKIs at some point of time during their treatment course with 7 patients having received frontline TKI therapy. Response assessment for patients receiving TKI showed partial response in 5 out of 19 patients, stable disease in 4 out of 19 patients and progression in 3 patients. Formal response assessment was not available for 6 patients. The median PFS of patients treated with TKIs was 5.0 months. The median OS of the whole EGFR positive SCC cohort was 6.6 months. On univariate analysis, patients having received TKI was the only factor associated with a significantly better median OS of 13.48 months vs 2.58 months (p = 0.000). Patients with exon 19 mutation tended to have better overall survival (p = 0.059). On multivariate analysis using Cox Regression Analysis, patients receiving TKI therapy, ECOG performance status

Conclusions

EGFR mutation in SCC of lung predicts better outcome if given TKI but it may be inferior to the outcomes seen in adenocarcinoma patients.

Clinical trial identification

Legal entity responsible for the study

Tata Memorial hospital

Funding

Self funded

Disclosure

All authors have declared no conflicts of interest.