Background: Epidermal growth factor receptor (EGFR) gene mutations are recurrently observed in non-small cell lung carcinomas (NSCLCs), and it has been found that they may serve as specific therapeutic targets. The aim of the present study was to determine the prevalence of EGFR gene mutations in NSCLCs in an East European (Bulgarian) population in different histological subtypes, in cytological versus histological samples and in primary versus metastatic lesions.
Methods: In this study 1427 NSCLC samples were included. DNA was extracted from either formalin-fixed paraffin embedded (FFPE) tissues or cytology specimens and analyzed for the presence of 29 recurrent EGFR gene mutations using SARMS PCR.
Results: EGFR gene mutations were found to occur significantly more often in female than in male patients (19.4% vs. 5.4%; p<0.001), in adenocarcinomas than in squamous cell carcinomas or other histological subtypes (12.5% vs. 6.2%, and 7.6%, respectively; p=0.009), and in never smokers than in ex-smokers and current smokers (22.9% vs. 8.5% and 4.9%, respectively; p<0.001). No significant differences were observed in the occurrence of EGFR gene mutations in primary tumors compared to metastases (7.9% vs. 11.2%; p=0.092), or in FFPE samples compared to cytological samples (8.9% vs. 8.1%; p=0.813).
Conclusions: Our data show that the overall frequency of EGFR gene mutations in lung adenocarcinomas in the East European cohort studied is within the range of that observed in North American and West European populations, but that its frequency in squamous cell carcinomas is higher than that in any population reported to date. All specimens appeared to be suitable for EGFR gene mutation analysis, irrespective nature or origin.