Abstract 1144P
Background
Treatment strategies and outcomes in pts with initially brain-only metastatic (m) NSCLC are not well understood. We evaluated strategies/outcomes specifically in such pts by presence or absence of EGFR/ALK mutations.
Methods
Clinico-demographic, treatment & survival data were analyzed retrospectively for all mNSCLC pts who had brain-only mets at time of initial stage IV diagnosis, years 2014-2016, at Princess Margaret Cancer Centre. Pts were grouped into two cohorts: NSCLC wildtype (NSCLCwt) and NSCLC with an ALK/EGFR mutation (NSCLCmut+). Log-rank tests were used to assess survival differences between groups.
Results
109 pts had brain-only mets at first diagnosis of mNSCLC: median age, 68 yrs; 51% female; 69% Caucasian; 76% ever-smokers; 76% had adenocarcinoma and 25% (n=27) had EGFR/ALK mutations. While 41 (38%) pts had brain-only progression (PD) subsequently, 22 (20%) developed systemic mets. NSCLCmut+ pts were more likely to develop systemic PD (37%) than NSCLCwt (15%, p=0.03). In patients with systemic PD, median time to first systemic met was 8.5 mos in NSCLCwt pts and 21.0 mos in NSCLCmut+ pts (p=0.23). With a median event-free observation time of 17.7 mos, median overall survival (OS) was 15.9 [95%CI: 11.5-21.3] mos. Median OS was 12.3 [7.4-18.4] mos for pts with NSCLCwt and 38.9 [ 21.3-not reached (NR)] mos in NSCLCmut+ pts (p=0.09). In 70 pts with de novo brain-only mets, the primary tumor was also locally treated (in addition to local brain mets treatment) in 30 (43%) pts, whereas in 40 (57%) pts the primary was not treated. In pts with NSCLCwt, there was no OS difference depending on whether there was local treatment of the primary tumor (p=0.68). In contrast in NSCLCmut+ pts, acknowledging the bias of treatment by indication and the small sample size, pts with local treatment of primary tumor had a greater OS (median OS NR vs 21.5 months, p=0.05).
Conclusions
In pts with brain-only NSCLCwt at stage IV diagnosis, we observed a brain-predominant pattern of failure whereas patients with NSCLCmut+ were more likely to develop systemic mets. Improved OS may occur by locally treating the primary tumor in patients with NSCLCmut+.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.