Abstract 1356P
Background
Up to 40% of NSCLC patients develop brain metastases (mets) during the course of their disease. We explored the impact of histology and EGFR and ALK mutations on cumulative incidence rates of brain mets and influence of brain imaging patterns.
Methods
Among all stage IV NSCLC patients seen at the Princess Margaret Cancer Centre diagnosed between Jan 1, 2014 and Dec 31, 2016, clinicopathologic characteristics, cumulative incidence of brain metastases and frequency of baseline and monitoring brain imaging until occurrence of first brain mets were analysed. Competing risk models compared cumulative incidence rates between histology/mutation groups.
Results
Of 920 eligible patients, median age was 68 years; 55% were male; 81% had adenocarcinomas; 31% were never-smokers. Among those with adenocarcinomas, 29% were EGFR+, 5% ALK+; 59% wildtype (WT); and 8% uncharacterized. Adenocarcinoma patients with EGFR+/ALK+ mutations were 64% female; 68% never-smokers, and 38% of Asian ethnicity. Overall, 90% patients had brain imaging (81% MRI) performed at diagnosis of stage IV disease: 95% EGFR+/ALK+; 89% WT adenocarcinoma; 88% SCC. The cumulative incidence rates of brain metastases at baseline, 1, 3 and 5 years were greater in adenocarcinoma patients with driver mutations even when adjusted for differences in survival (p < 0.001): 46%, 50%, 64%, 71% respectively in EGFR+ patients; 31%, 39%, 53%, 62% in ALK+; 36, 38%, 40%, 44% in WT adenocarcinoma; and 23%, 27%, 30%, 32% in squamous cell carcinoma (SCC). Table: 1356P
Cumulative incidences of brain metastases in NSCLC at Princess Margaret Cancer Centre
| Time | Adeno EGFR+ (%) | Adeno ALK+ (%) | Adeno WT (%) | SCC (%) |
| Baseline | 46 | 31 | 36 | 23 |
| 1 year | 50 | 39 | 38 | 27 |
| 3 year | 64 | 53 | 40 | 30 |
| 5 year | 71 | 62 | 44 | 32 |
P<0.001.
Conclusions
Our real-world data confirm a higher cumulative incidence of brain metastases in EGFR+/ALK+ adenocarcinoma compared to WT or SCC and more brain imaging at baseline. Future analyses will focus on treatment-based outcomes (tyrosine kinase inhibitors, different radiation modalities) in EGFR+/ALK+ patients compared to WT adenocarcinoma and SCC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
S. Schmid: Financial Interests, Institutional, Advisory Board: BMS; Financial Interests, Institutional, Advisory Board: MSD; Financial Interests, Institutional, Advisory Board: Boehringer Ingelheim; Financial Interests, Institutional, Research Grant: BMS; Financial Interests, Institutional, Research Grant: AstraZeneca; Financial Interests, Institutional, Other: Takeda; Financial Interests, Institutional, Other: MSD; Financial Interests, Institutional, Other: Boehringer Ingelheim. All other authors have declared no conflicts of interest.