Mutations in the Epidermal Growth Factor Receptor Gene in Non-Small-Cell Lung Cancer Patients and Egfr Serum Levels

ABSTRACT Background Determine the existing mutations in the epidermal growth factor receptor (EGFR) gene in non-small-cell lung cancer (NSCLC) patients and correlate with survival. Also pretreatment EGFR serum levels were quantified and analyzed if there were differences between patients with or without mutations. Methods From July 09 and July 11 serum samples were collected before starting erlotinib. Serum levels of EGFR were quantified using an ELISA. Patients were examined for mutations in tissue by EGFR Mutation Test Kit cobas. SPSS was used to calculate overall survival (OS) and progression-free survival (PFS). Mann-Whitney U test was used for comparison of EGFR serum level. Results 58 patients were studied but we obtained information of mutations in 34 patients. All variants were found in exons 18, 19 and 21 of EGFR. No mutation was found in exon 20, only two polymorphisms. Of 32 patients analyzed, we detected a total of 11 mutations (34.4%). In exon 19 we found 8 mutations (del19) and affected 8 patients (72.7% mutations). In exon 21 we found two mutations (L858R and L861Q), each in 1 patient (18.2% mutations). In exon 18, G719X mutation was found in 1 patient (9.1% mutations). The remaining patients (65.6%) were wild type. Patients wild type have a median OS of 5.4 months (95% CI, 4.2 - 6.6) and mutated patients 12.6 months (95% CI, 4.7- 21.1); p = 0.033. In terms of PFS, wild type patients have a median PFS of 2.8 months (95% CI: 2.0 - 3.6) and mutated 8.6 months (95% CI 2.0 - 15.1); p = 0.012. We determined serum levels of EGFR in 44 patients with a mean of 57.5 ng/mL. Of these patients, 21 were wild type, 7 were mutated and 16 showed an unknown mutational status. In wild type patients, the mean serum levels of EGFR was 57.8 ng/mL and in the mutant was 62.3 ng/mL. Conclusion Patients with EGFR gene mutation have a higher OS and PFS. No differences were found in EGFR serum levels prior to erlotinib treatment between wild type and mutated patients. Disclosure All authors have declared no conflicts of interest.