Introduction: Lung cancer presents the highest mortality among cancer deaths worldwide. The various types of mutation within lung adenocarcinoma show different prognosis. Our study aims to evaluate the survival outcomes of Stage IV Lung adenocarcinoma patients from 2014 to 2018 in our hospital. 

Material and methods: 454 Stage IV lung adenocarcinoma patients are retrospectively enrolled in the study. EGFR tests are routinely applied.

Results: 272 patients were EGFR positive. 127(46%) patients had exon 19 deletion while 106 (39%) patients had exon 21 L858R mutation, 39(14%) patients had EGFR other mutations. The Kaplan Meier curve shows that EGFR positive patients have better survival than EGFR negative patients. Exon 19 deletion positive patients showed better survival outcome compared to the exon 21 L858R mutation. The Kaplan Meier curve shows the much better survival in patients who developed T790M mutation than those who did not develop T790M mutation.

Conclusion: The positive EGFR mutation results imply the better prognosis due to the evolution of targeted therapy. The finding of T790M mutation after the initial targeted therapy is common and the prognosis is better after the use of Osimertinib.