Introduction: Today, recommendations about initial Response Evaluation Criteria in Solid Tumor (RECIST) and its frequency still vary, while early diagnosis of progression affects patient’s prognosis and subsequent treatment options. Methods: This study aims to examine Progression Free Survival (PFS) of positive EGFR mutations advanced lung adenocarcinoma receiving Tyrosine Kinase Inhibitor (TKI) and factors that influence it. This was an observational study with retrospective cohort design conducted at Prof IGNG Ngoerah Hospital from January to December 2021. Sample was data from Epidermal Growth Factor Receptor (EGFR) positive mutation advanced lung adenocarcinoma patient who were treated with EGFR-TKI at Prof IGNG Ngoerah Hospital, Denpasar, Bali from January 2017 to February 2021. Total sample was 63. Results: Median PFS was 12 months (95% CI 10.28 – 13.71) and minimum PFS was 3 months. In univariate analysis, Hazard Ration (HR) of older age, smoker, distant metastasis, brain metastasis, increased Neutrophil-to-Lymphocyte Ration (NLR), and exon 21 mutation to shorter PFS was 0.99 (95% CI 0.95-1.02); 1.03 (95% CI 0.57-1.85); 1.45 (95% CI 0.85-2.49); 2.14 (95% CI 1.02-4.49); 1.08 (95% CI 1.03-1.13); and 1.21 (95% CI 0.67-2.18). Multivariate analysis showed only increased NLR affected PFS significantly with HR 1.06 (95% CI 1.007-1.13). Conclusion: Median PFS of EGFR positive mutation advanced lung adenocarcinoma patients who received TKI was 12 months and minimum value was 3 months. Increased age, smoking, distant metastases, brain metastases, and exon 21 mutations were not associated with PFS. NLR significantly affected PFS.