Continuous Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor Treatment May Not Hinder the Survival of Patients with Primary Lung Adenocarcinoma despite Indolent New Lesions

Background: Lung adenocarcinoma treated with epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI) eventually develops progressive disease (PD) due to acquired resistance. However, since there are few published reports on the survival benefit of continuous EGFR-TKI administration for indolent new lesions, the present study retrospectively analyzed the possible treatment effect on PD status as defined by the Response Evaluation Criteria in Solid Tumors (RECIST). Methods: From January 2005 to November 2009, the data of 37 lung adenocarcinoma patients were prospectively recorded and retrospectively analyzed and evaluated. All patients had at least 6 months of progression-free survival (PFS) with EGFR-TKI and definite new lesions during EGFR-TKI therapy, with the primary targeted lung lesions remaining regressive or stable. Twenty-six patients continued and 11 discontinued EGFR-TKI therapy. Overall survival (OS), survival after discontinuation of EGFR-TKI, and survival after the appearance of definite new lesions were compared. Results: The median OS was 480 days for the discontinuation group and 771.5 days for the continuation group (p=0.1838). Median survival time after discontinuation of EGFRTKI was 117.0 days and 143.0 days in the 2 groups, respectively (p=0.9106), while median survival time after the appearance of indolent new lesions was 152.0 days and 262.0 days, respectively (p=0.0571). Conclusion: Continuous EGFR-TKI administration in patients with primary lung adenocarcinoma with an initial response and the appearance of new indolent lesions may not hinder the survival benefit.