Risk factors for brain metastases in locally advanced non-small cell lung cancer with definitive chest radiation.

Purpose: We intended to identify risk factors that affect brain metastases (BM) in patients with locally advanced non-small cell lung cancer (LA-NSCLC) receiving definitive radiation therapy, which may guide the choice of selective prevention strategies.

Methods And Materials: The characteristics of 346 patients with stage III NSCLC treated with thoracic radiation therapy from January 2008 to December 2010 in our institution were retrospectively reviewed. BM rates were analyzed by the Kaplan-Meier method. Multivariate Cox regression analysis was performed to determine independent risk factors for BM.

Results: The median follow-up time was 48.3 months in surviving patients. A total of 74 patients (21.4%) experienced BM at the time of analysis, and for 40 (11.7%) of them, the brain was the first site of failure. The 1-year and 3-year brain metastasis rates were 15% and 28.1%, respectively. In univariate analysis, female sex, age ≤60 years, non-squamous cell carcinoma, T3-4, N3, >3 areas of lymph node metastasis, high lactate dehydrogenase and serum levels of tumor markers (CEA, NSE, CA125) before treatment were significantly associated with BM (P<.05). In multivariate analysis, age ≤60 years (P=.004, hazard ratio [HR] = 0.491), non-squamous cell carcinoma (P=.000, HR=3.726), NSE >18 ng/mL (P=.008, HR=1.968) and CA125 ≥ 35 U/mL (P=.002, HR=2.129) were independent risk factors for BM. For patients with 0, 1, 2, and 3 to 4 risk factors, the 3-year BM rates were 7.3%, 18.9%, 35.8%, and 70.3%, respectively (P<.001).

Conclusions: Age ≤60 years, non-squamous cell carcinoma, serum NSE >18 ng/mL, and CA125 ≥ 35 U/mL were independent risk factors for brain metastasis. The possibilities of selectively using prophylactic cranial irradiation in higher-risk patients with LA-NSCLC should be further explored in the future.