Why does lung cancer usually spread to the brain, thereby producing brain tumors?

Brain Mets. (metastasis) as an entity comprise 100k per year. Lung cancer leads the league, but breast, melanoma, kidney are quite common. Prostate almost never. Only rhabdoid tumors in children commonly go to brain. This pattern stares at us, but baffles us as to why "organotropic" patterns of metastasis are so predictable.