P16. Is type of EGFR mutation predictive for incidence and survival in lung adenocarcinoma patients with brain metastases?

Background: Lung adenocarcinoma tumours frequently progress to brain. Some investigators reported that incidence of brain metastases (BM) is higher for patients with exon 19 deletions and other mutations relative to L858R mutations. Aim of our study was to investigate if type of mutation is predictive for development and survival of patients with BM.

Methods: Medical records of 168 adenocarcinoma patients with BM and known EGFR mutation status were retrospectively analysed.

Results: Epidermal growth factor receptor (EGFR) mutations were present in 47 (28%) patients. Among 90 patients who had BM already at the time of diagnosis, 26 (29%) had EGFR mutations, while 21 (27%) EGFR mutations were present among 78 patients who developed BM later. Types of EGFR mutations are presented in Table 1. EGFR mutation types were equally distributed among patients with BM at diagnosis and those who developed them later. Patients progressed to brain after median 25.9 months (95% CI: 17.4-34.7) with no apparent influence of the type of mutation (P=0.8). Median survival of EGFR mutated patients with BM was 24.1 months (95% CI: 13.7-33.5), without difference among mutation types (P=0.18). Median survival after development of BM was 6.3 months (95% CI: 0.1-15.8), with a trend for longer survival in patients with deletion 19 compared to other mutation types, 12.6 months vs. 4.9 months, respectively (P=0.15).

Table 1 Types of epidermal growth factor receptor somatic gene mutations
Full table

Conclusions: Based on our results, type of mutation was not predictive for development of BM and survival of adenocarcinoma patients with BM, though no firm conclusions could be made due to small number of patients included.

Keywords: Non-small cell lung cancer (NSCLC); adenocarcinoma; epidermal growth factor receptor (EGFR) mutation; brain metastasis