THE BLOOD-BRAIN-BARRIER - IMPACT ON TREATMENT OF BRAIN-TUMORS

The blood-brain barrier prevents substances with molecular weights abo ve 500 d from penetrating from the blood into the central nervous syst em. Whereas this barrier is nonexistent in the central portions of mal ignant brain tumors, barrier function is normal in the outermost tumor al regions and adjacent cerebral tissue, where malignant cells may be present. Furthermore, corticosteroids given to combat intracranial hyp ertension restore normal barrier function. To increase delivery of che motherapy agents to brain tumors, several methods for circumventing th e blood-brain barrier have been studied but none is currently used in routine clinical practice.