The present invention relates to the field of cellular and molecular therapy with modified (genetically or growth factor engineered) and unmodified stem cells (SCs). More particularly, the invention relates to a method of systemic treatment of central nervous system (CNS) and other tumors in both intracranial/intraspinal and extracranial/extraspinal sites, using neural stem cells (NSCs), a prototype for solid organ, non-hematopoietic stem cells.