1625PCLINICAL MANIFESTATIONS OF EGFR GENE MUTATIONS IN PATIENTS WITH ADENOCARCINOMA OF THE LUNG AMONG INHABITANTS OF THE SOUTH RUSSIAN REGION

ABSTRACT Aim: EGFR mutations are predictors of both response to chemotherapy and survival regardless of the therapy and response to inhibitors of EGFR tyrosine kinase. EGFR mutations are observed in approximately 10% of the European population and 30-50% of the Asian population. The multiethnic population of the South Russian region historically and geographically is essentially a border community of peoples, in which the studyi of EGFR mutations is highly relevant. Methods: This study included 140 patients with adenocarcinoma of the lung, aged from 34 to 77 years. Men - 88 (62,8%), women - 52 (37,2%). Slavs - 108 (77,2%), Caucasians - 32 (22,8%). Never-smokers – 65 (46,4%), current and former smokers - 75 (53,6%). Symptomatic disease – 116 (82,8%), asymptomatic - 24 (17.2%). Central tumors in 32 (22,8%), peripheral - 108 (77,2%). Stage I - 43 (30,7%), II - 20 (14,3%), IIIA - 9 (6,4%), IIIB - 27 (19,3%), IV – 41 (29,3%) cases. The degree of differentiation adenocarcinoma: G1 - 3 (2,1%), G2 - 63 (45%), G3 - 74 (52,8%). EGFR RGQ PCR Kit (QIAGEN, Germany) was used for identification of somatic mutations of the EGFR gene in samples of tumor tissue. Results: 29 (18,6%) EGFR gene mutations were revealed, including: L858R in exon 21 - 53,8%, deletion of exon 19 - 38,5% and insertion into exon 20 - 7,7%. Mutant type EGFR was observed in G1 and G2 tumors 3 times more often than in G3 (X2=8.6; p=.0033), 4 times more often in women than in men (X2=17.7; p=.00001) and in patients older than 55 years (X2=6.1; p=.00001), 5 times more often in never-smokers (X2=15.1; p=.00001). In the group of patients with asymptomatic disease, 75% of which had stage I-II of the disease, mutant type EGFR was found in 33.3% of observations (L858R mutation - 75%, deletion of exon 19-25%), which exceeded the total indicator of 18.6% approximately twice. All these patients with exclusively the peripheral form of the disease were over 55 years, 88% of cases of EGFR mutations were observed in G2 and 12% in G3 (X2=4.2; p=.04). Conclusions: Frequency of EGFR mutations in the population of the South Russian region, which occupies an intermediate position, with clinical manifestations similar to those typical for the Asian population, was detected for the first time. Disclosure: All authors have declared no conflicts of interest.