Most brain tumors are difficult to treat due to the fact that they don't pass through the blood brain barrier. The blood-brain barrier (BBB) is a diffusion barrier, which impedes influx of most compounds from blood to brain. Three cellular elements of the brain microvasculature compose the BBB-endothelial cells, astrocyte end-feet, and pericytes (PCs). Tight junctions (TJs), present between the cerebral endothelial cells, form a diffusion barrier, which selectively excludes most blood-borne substances from entering the brain. Astrocytic end-feet tightly ensheath the vessel wall and appear to be critical for the induction and maintenance of the TJ barrier, but astrocytes are not believed to have a barrier function in the mammalian brain. Dysfunction of the BBB, for example, impairment of the TJ seal, complicates a number of neurologic diseases including stroke, neuroinflammatory disorders and brain tumors. The size of the opening of the blood brain barrier is about 2.3 nm to 10.2 nm, this hampers the majority of drugs to pass through the barrier as the normal drugs are sized more than 750nm. The Ray of hope lies in the molecules sized less than 10.2nm. Mistletoe lectins which have a cytotoxic effect as well as an immunomodulatory effect are sized between 0.46nm to 0.5nm making it extremely easy to pass through the BBB. An additional benifit is the liposome which carry the mistletoe lectin right to the tumor cells and enter the cells by receptor based endocytosis and there by inducing apoptosis. Regards Dr Sandeep Roy MD (Practice of Medicine) AEMT (Germany) Specialist in Integrative Oncology. Nashik.