165P: Long noncoding RNA LUCAT1 is associated with poor prognosis in human non-small cell lung cancer and affects cell proliferation via regulating p21 and p57 expression.

were collected between July 2013 and November 2015. DNA was extracted from formalin-fixed paraffin-embedded (FFPE) tumor tissue, using the Cobas® DNA Sample Preparation Kit. For the mutational screening we used the Cobas® EGFR Mutation Test v2. performed on the Cobas® 4800 System. All mutations were detected at 5% sensitivity with the exception of the 2240_2257del18 exon 19 deletion mutation, detected at a sensitivity of >10%. Presence of more than 50% adequate tumor tissue was confirmed by a pathologist. Results: Histological evaluation found 380 (86.4%) cases with adenocarcinoma, 40 (10%) with squamous-cell carcinoma and 20 (4.6%) with NSCLCNST. From all 440 tested samples in 58 (13.2%) we found mutation in the EGFR gene. By 37 (63.8%) of them (15 male, 22 female) it was an activating mutation in EGFR gene and by 21 (36.2%) mutations were linked to insensitivity to TKIs. The prevalent type of activating EGFRmutation was deletion in exon 19 (in 24 cases – 64.9%), in 11 (29.7%) cases – L858 in exon 21, in 1 (2.7%) case – S768I in exon 20 and by one patient we found double heterozygosity – S768I in exon 20 and G719X in exon 18. Half of the patients were non-smokers. 97.3% of the tumor samples with activating mutations were adenocarcinomas, the rest with histology for squamous-cell carcinoma. 81.1% of the samples were from the primary tumor and the rest from the secondary metastasis. All patients with activating mutations were treated with first line TKIs according to guidelines. Conclusions: This study successfully provided insights into the prevalence and type of the EGFR gene mutation, which was detected in 13.2% of the studied Bulgarian population and corresponds to the publicly available data. Legal entity responsible for the study: Medical University Pleven, Department of Pathology Funding: Roche national program for patient support and EGFR testing Disclosure: All authors have declared no conflicts of interest.