Progression patterns at RECIST PD during EGFR-TKIs in advanced NSCLC patients harboring EGFR mutation.
8078 Background: The progression patterns at RECIST PD during EGFR-TKIs in advanced NSCLC patients harboring EGFR mutation are clinically heterogeneous. The aim of this study is to evaluate progression patterns at RECIST PD during EGFR-TKIs in advanced NSCLC patients harboring EGFR mutation. Methods: From 2008 to 2012, 160 consecutive patients with advanced NSCLC harboring EGFR mutation were treated with EGFR-TKIs (erlotinib or gefitinib) at our institution. Among these patients, 104 patients who experienced RECIST PD assessed by radiologic findings were retrospectively evaluated for initial response on EGFR-TKIs, progression sites, focus of progression (solitary lesion or multiple lesions), patients status at RECIST PD, and post progression survival (PPS) from RECIST PD. Results: In 104 patients, 96 (92%) patients had EGFR major mutation (Exon 19 deletion and L858R), and 49 (47%) received EGFR-TKIs as first-line. The overall response rate and median progression free survival on EGFR-TKIs was 69 % and 8.2 months. At the time of RECIST PD, 44 (42%) patients had symptomatic, and 60 (58%) had asymptomatic. The progression sites were isolated CNS in 17 (16%) patients, isolated bone in 7 (7%), isolated pulmonary in 13 (12%), systemic in 67 (65%) patients. In the focus of progression, 24 (23%) patients have solitary lesion, and 80 (77%) have multiple lesions. After RECIST PD, 40 (38%) patients continued EGFR-TKIs, 25 (24%) were switched to cytotoxic agents, and 39 (38%) had best supportive care. 10 (10%) patients received local radiotherapy for isolated progression site (brain 6; bone 3; lung 1) and 8 of these patients continued EGFR-TKIs. The median PPS from RECIST PD was 10.6 months. Multivariate analysis identified that asymptomatic or solitary progression lesion at RECIST PD were associated with significantly longer PPS (asymptomatic: HR 0.34, 95% CI 0.19-0.58, P<0.001; solitary progression lesion: HR 0.39, 95% CI 0.16-83, P=0.013). Conclusions: The progression patterns at RECIST PD during EGFR-TKIs in advanced NSCLC patients harboring EGFR mutation have widely diversity. Further investigation for association between progression patterns at RECIST PD and clinical outcome after RECIST PD is warranted.