473P Driver oncogene status in early-emerging lung adenocarcinoma

Aim/Background: EGFR, Kras mutations are frequently positive in adenocarcinoma among all lung cancers. HER2, BRAF mutations or EML4-ALK, RET, ROS1 translocations are identified in lesser numbers. Although adenocarcinomas emerging in younger patients are presumably associated with some driver oncogenes including these mutations/translocations, details remain unknown. Methods: We retrospectively screened 67 consecutive patients who were diagnosed as stage I-IV adenocarcinoma at the age of 40 years or less in 2009-2014. We analyzed clinical and genetic characteristics among them. Results: Out of 67 patients, 27 (40%) were male, 26 (39%) were never-smoker, and 45 (68%) were stage IV, with the median age of 36 years (range; 26-40). Fifty-five patients (82%) were identified with some driver oncogene. Thirty (45%) had EML4-ALK translocation, 19 (28%) had EGFR mutation, and 2 (3%) had Kras mutation. Most of the EGFR-mutant patients had exon 19 deletion (14/19; 74%). Furthermore, we examined rare oncogenes in 12 out of 15 triple-negative patients, which revealed three patients had HER2 mutation and two had RET translocation. Twenty-six stage IIIB-IV patients with EML4-ALK translocation received ALK-inhibitors; the median progression-free survival was 8.9 months (95% CI: 4.8-10.8 months). Conclusions: 82% of early-emerging adenocarcinoma was identified with some targetable driver oncogenes. Among younger populations, examination of all known driver oncogenes is recommended. Disclosure: All authors have declared no conflicts of interest.