Abstract. The survival time of non-small cell lung cancer (NSCLC) patients with brain metastases has been previously reported to be 6.5-10.0 months, even with systematic treatment. Patients that possess a certain epidermal growth factor receptor (EGFR) mutation alongside NSCLC with brain metastases also have a short survival rate, and a reliable prognostic model for these patients demonstrates a strong correlation between the outcome and treatment recommendations. The Cox proportional hazards regression and classification tree models were used to explore the prognostic factors in EGFR mutation-positive NSCLC patients with brain metastases following whole-brain radiation therapy (WBRT) and EGFR-tyrosine kinase inhibitor (EGFR-TKI) treatment. A total of 66 EGFR mutation-positive NSCLC patients with brain metastases were retrospectively reviewed. Univariate and multivariate analyses by Cox proportional hazards regression were then performed. The classification tree model was applied in order to identify prognostic groups of the patients. In the survival analysis, age, carcinoembryonic antigen (CEA) and status of the primary tumor were prognostic factors for progression free survival (P=0.006, 0.014 and 0.005, respectively) and overall survival (P= 0.009, 0.013 and 0.009, respectively). The classification tree model was subsequently applied, which revealed 3 patient groups with significantly different survival times: Group I, age <65 years and CEA ≤10 µg/ml; Group II, age <65 years and CEA >10 µg/ml or age ≥65 years and CEA ≤10 µg/ml; and Group III, age ≥65 years and CEA >10 µg/ml. The major prognostic predictors for EGFR mutation-positive NSCLC patients with brain metastases following WBRT and EGFR-TKI were age and CEA. In addition, primary tumor control may be important for predicting survival.
IntroductionPatients with non-small cell lung cancer (NSCLC) possess a high risk of developing brain metastases. The incidence rate of brain metastases for patients with lung cancer is 23-65% (1). Once intracerebral metastases develop, the prognosis is poor. The median survival time for patients with untreated brain metastases is only ~1 month (2,3). The principle therapeutic modality for brain metastases is whole-brain radiation therapy (WBRT), and the median survival time following this treatment may increase to 4-6 months. Although therapies, including surgery, WBRT, stereotactic radiotherapy and systematic chemotherapy, are rapidly improving, the prognosis of patients with brain metastases from lung cancer remains poor, and the median survival time for patients remains at ~6.5-10 months (4-7).In 2004, the genes encoding the read code box of epidermal growth factor receptor (EGFR) were sequenced (8). In addition, the gene mutation status has been elucidated and is now widely used in clinical practice. As a result, the identification of the EGFR mutation and the introduction of treatment with EGFR-tyrosine kinase inhibitors (EGFR-TKI) has improved clinical outcomes (9). EGFR-TKI regimens have a good efficacy against brain...