Risk factors for brain metastases from non-small-cell lung cancer: A protocol for observational study

Brain metastasis is a common site of distant metastasis of non-small-cell lung cancer (NSCLC) that greatly reduces the prognosis of patients. In this study, we explored the correlation between different clinical factors and secondary brain metastases in NSCLC in an attempt to identify NSCLC patient populations at high risk of metastasis to the central nervous system. We collected data for 350 NSCLC patients from the medical record system of the First Affiliated Hospital of Nanchang University from June 2015 to June 2019, and these patients had pathologically verified diagnoses. The correlations between age at the time of diagnosis, sex, histological type, calcium concentration, hemoglobin (HB), fibrinogen (Fbg), activated partial thromboplastin time (APTT), alkaline phosphatase (ALP), carcinoembryonic antigen (CEA), CA125, and CA199 levels and brain metastasis were analyzed. Multivariate logistic regression analysis was used to identify risk factors for NSCLC brain metastasis. A receiver operating characteristic (ROC) curve was used to calculate the cutoff, sensitivity, and specificity of the independent related factors. Of the 350 patients, 57 were diagnosed with brain metastases. Univariate and multivariate logistic regression analysis indicated that lesion diameter, calcium concentration, and CEA level were independent risk factors correlated with brain metastasis (P < .05). There were no significant differences in age, sex, type of histopathology, presence or absence of mediastinal lymph node metastasis, HB, Fbg, APTT, ALP, cancer antigen 125 (CA-125), or cancer antigen 199 (CA-199) levels between patients with brain metastases and patients without brain metastases (P > .05, respectively). ROC curves demonstrated that these factors had comparable accuracy in predicting brain metastasis (area under the curve [AUCs] were 0.620, 0.661, and 0.729, respectively). The cutoff values for lesion diameter, calcium, and CEA were 5.050 cm, 2.295 mmol/L, and 11.160 ng/mL, respectively. The sensitivities for prediction brain metastasis were 59.6%, 64.9%, and 73.3%, with specificities of 63.1%, 59.2%, and 70.3%, respectively. According to our study, lesion diameter, calcium concentration, and CEA level are independent risk factors for brain metastases in NSCLC patients. Thus, we can strengthen the regular follow-up of NSCLC patients with tumor diameter > 5.050 cm, calcium > 2.295 mmol/L, CEA > 11.160 ng/mL, and use these factors as a reference for preventive treatments.