Epidermal Growth Factor Receptor Activating Mutations in Squamous Histology of Lung Cancer Patients of Southern Bulgaria

AbstractThere is only limited data on the prevalence of epidermal growth factor receptor (EGFR) activating mutations in squamous cell carcinomas and adenosquamous carcinomas of the lung in patients of the Southern Bulgarian region and the efficacy of EGFR tyrosine kinase inhibitors. AIM: Previous reports for Bulgarian population showed high incidence of EGFR mutations in the squamous cell carcinomas, so we set the goal to investigate their frequency in Southern Bulgaria, after precise immunohistochemical verification of lung cancers. MATERIALS AND METHODS: Two hundred and thirty-six lung carcinomas were included in this prospective study. All biopsies were initially analysed with p63, TTF1, Napsin A, CK7, CK34βE12, synaptophysin, CK20 and CDX2. Two hundred and twenty-five non-small cell lung carcinomas were studied with real-time PCR technology to assess the status of the EGFR gene. RESULTS: We detected 132 adenocarcinomas (58.7%), 89 squamous cell carcinomas (39.2%), 4 adenosquamous carcinomas (1.8%), 9 large cell neuroendocrine carcinomas (3.8%) and 2 metastatic colorectal adenocarcinomas (0.8%). Activating mutations in the EGF receptor had 3 out of 89 squamous cell carcinomas (3.37%). We have established mutations in L858R, deletion in exon 19 and rare mutation in S7681. One out of four adenosquamous carcinomas had a point mutation in the L858R (25%). CONCLUSIONS: The frequency of EGFR mutations we found in lung squamous cell carcinomas in a Southern Bulgarian region is lower than that in European countries. Ethnic diversity in the region does not play role of an independent predictive factor in terms of mutation frequency.