CLRM-21 RISK FACTORS ASSOCIATED WITH THE PRESENCE OF BRAIN METASTASIS AT THE MOMENT OF DIAGNOSIS IN LUNG CANCER PATIENTS: RETROSPECTIVE CASE SERIES

BACKGROUND: Lung cancer (LC) is the second most frequent neoplasm worldwide and it is commonest origin of brain metastases (BM). The aim of this study is to identify clinical, histological and molecular variables associated with a higher risk of BM at diagnosis in LC patients. METHODS: A retrospective single-centre case series analysis of patients with a new diagnosis of LC (from 2015 to 2018) was performed. A total of 723 newly diagnosed LC patients were identified and only those with a brain imaging study were included. Non-parametric statistical tests were used to compare patients with or without metastases at diagnosis. Uni- and multivariate analysis was performed to identify risk factors associated with the presence of BM. Statistical significance was considered when p<0.05. RESULTS: 185 patients with newly diagnosed LC and brain imaging at diagnosis were included (mean age 64.69 years [SD= 10.34]; 71.9% male). 40% of patients had BM at diagnosis. No significant differences in clinical, histological and molecular variables were identified. In any case, survival analysis showed that BM at diagnosis was associated with worse overall survival (Log-Rank test, p<0.01). Univariate analysis showed that presenting neurological symptoms (OR=19.5, p<0.0001 CI [7.895-47.65]), adenocarcinoma (OR= 2.113, p<0.014 CI [1.160-3.849]), small cell carcinoma (OR=0.372, p<0.008 CI [0. 179-0.773]) and visceral metastases (OR= 14.444, p<0.0001 CI [6.161-33.86]) or metastases limited to the thorax (OR= 0.019, p<0.001 CI [0.003-0.146]) were associated with BM at diagnosis. However, only neurological symptoms (OR= 20.290, p<0.0001 CI [4.953-83.118]), visceral metastases (OR= 4.451, p<0.010 CI [1.458-13.777]) and/or metastases limited to the thorax (OR= 0.066, p<0.024 CI [0.006-0.010]) reached statistical significance in multivariate analysis. CONCLUSIONS: Neurological symptoms and the presence of visceral metastases are independent predictors of developing BM at diagnosis in LC patients. However, LC disease confined to the thorax is associated with a lower risk of developing BM.