Clinical predictors of metastatic disease to the brain from non-small cell lung carcinoma: primary tumor size, cell type, and lymph node metastases.

PURPOSE: To retrospectively assess possible clinical predictors of metastatic disease to the brain in patients with non-small cell lung carcinoma (NSCLC).
MATERIALS AND METHODS: Institutional review board approval was obtained, informed consent was waived, and data and other information were obtained prior to implementation of HIPAA. A review was performed of 264 patients (mean age, 65 years; 158 men and 106 women) with NSCLC who had undergone imaging studies of the chest and head. Hierarchical logistic regression was used to determine the predicted probability of metastatic disease to the brain as a function of patient age and sex and of size, cell type, peripheral versus central location, and lymph node stage of the primary NSCLC.
RESULTS: Ninety-five (36%) patients had evidence of metastatic disease to the brain. Mean diameter of the primary tumors was 4.0 cm +/- 2.2 (standard deviation). Cell types included adenocarcinoma (136 [52%] patients), undifferentiated (68 [26%] patients), and squamous (47 [18%] patients), for which metastatic disease to the brain occurred in 43%, 41%, and 13% (P = .003) of patients, respectively. The predicted probability of metastatic disease to the brain correlated positively with size of the primary tumor (P < .001), cell type (adenocarcinoma and undifferentiated vs squamous, P = .001), and lymph node stage (P < .017) but did not correlate with age, sex, or primary tumor location. For primary adenocarcinoma without lymph node spread, the predicted probabilities of metastatic disease to the brain from 2- and 6-cm primary tumors were .14 (95% confidence interval: .06, .27) and .72 (95% confidence interval: .48, .88), respectively (P < .02).
CONCLUSION: The probability of metastatic disease to the brain from primary NSCLC is correlated with size of the primary tumor, cell type, and intrathoracic lymph node stage.