Intratumoral heterogeneity of EGFR mutation and clinical significance in Chinese patients with advanced non-small cell lung cancer.

7537 Background: Whether exist intratumoral heterogeneity of epidermal growth factor receptor (EGFR) gene mutation remains controversial. This study aims to evaluate intratumoral heterogeneity of EGFR and its clinical significance in patients with non-small cell lung cancer (NSCLC). Methods: Samples were collected from 85 patients with stage IIIa-IV who had palliative surgery resection. All of the bulk tissues had been routinely detected EGFR mutation, in which contained 30 wild-type and 55 mutant-type EGFR. 28–34 tumor foci for each sample were microdissected. EGFR mutation was detected by ARMS. EGFR copy number was detected by FISH. 23 patients received EGFR-tyrosine kinase inhibitor (TKIs) therapy. Results: 1740 tumor foci from 55 EGFR mutant-type (Group-M) and 959 foci from 30 wild-type cases(Group-W) were fractionated. Mean mutation contents were 73.9%(1285/1740) in Group-M and 0 in Group-W. Accordingly, 28.2%(24/85)consisted of cells with both wild-type and mutated-type EGFR, with the proportion of ...