Over-expression of S100B protein as a serum marker of brain metastasis in non-small cell lung cancer and its prognostic value.

Validated serum biomarkers for patients suffering from non-small cell lung cancer (NSCLC) brain metastasis are urgently needed for early diagnosis, treatment monitoring, and prognostic classification in daily clinical practice. Serum S100B was reported to be a marker of leaky blood-brain barrier (BBB), which was often caused by brain tumors. This study aimed to investigate the role of S100B in NSCLC brain metastasis. The results showed that serum S100B correlated significantly with NSCLC brain metastasis (P < 0.001). When evaluated by the ROC curve, at the cutoff point 13.83 pg/ml, the sensitivity and specificity were 94% and 93%, respectively (AUC= 0.938, P < 0.001). High level of serum S100B was significantly correlated with a higher number of brain metastases and significantly worse prognosis (P <  0.05). In addition, S100B was an independent prognostic factor (P <  0.001). In conclusion, serum S100B was a sensitive and specific marker for early detection of brain metastasis in NSCLC and could be used as a surveillance tool for prognosis evaluation.