PUB122 Effects of Whole Brain Radiotherapy for Brain Metastases from Lung Adenocarcinoma with or without EGFR Mutations

Our purpose was to analyze the association between WBRT efficacy and EGFR status of BM patients from lung adenocarcinoma. The data of NSCLC were retrospectively reviewed from August 2010 to May 2015, 1391 NSCLC patients with EGFR mutations status referred to Shanxi Cancer Hospital. 304 patients were diagnosed with BM. Among them, 89 patients who received WBRT were eligible for this study. Eighty -nine lung adenocarcinoma patients with BM received WBRT. The standard regimen was 30 Gy in 10 fractions or 40 Gy in 20 fractions. The radiographic response rate (RR) in BM after WBRT, intracranial progression-free survival (IFS) and overall survival (OS) were analyzed. The log-rank test and Cox regression tests were used to confirm the influence of different variables on IPFS and OS. Among all the patients, the total RR was 61.8% (17 with CR and 38 with PR). In uni-variate testing, patients with mutant EGFR had a better RR than those with wild type (86.4% vs 53.7%，P = 0.011). By multivariate analysis, the following were significantly associated with higher radiotherapy RRs : EGFR mutations (OR = 4.262, 95% CI = 1.105-16.435; P = 0.035) and KPS at BM (OR = 8.344, 95% CI =1.688-41.252; P = 0.009). At the end of the 6-month follow-up, there were 63 patients still alive. The median survival time was 12 months (95% CI 9.535-14.465). By the log-rank test, the following were associated with a much longer IPFS: EGFR mutation (P = 0.007), KPS at BM (P<0.001), and control of primary tumor (P = 0.008). Multivariate analysis further revealed that EGFR mutation and KPS scores at BM were independent effectors (Table 3, Figure 1). The univariate analysis revealed that being female (P = 0.066), control of primary tumor (P =0.002), and higher KPS scores (P <0.001) were associated with longer OS. Consistently, by the multivariate analysis, the independent prognostic factors were KPS (P<0.001), and control of primary tumor (P = 0.031). our results suggest that EGFR mutations in BM from lung adenocarcinoma were significantly associated with a better treatment response and a longer IPFS after WBRT, relative to patients without EGFR mutations. However, an influence on OS was not observed. Prospective clinical randomized testing with more patients is needed.