How is metastasis characteristic of of benign and malignant tumor?

Spread to tumor to site discontinuous w/primary tumor, marker of malignancy, invasiveness permits them to vessels and lymphatics and cavities, 30% pt w/solid mass have evident metastases, 20% have occult metastases. More anaplastic more metastasis possible, exception are extremely small cancers metastasize. Most malignant cancers metastasize but some infrequent (basal cell carcinoma of skin), most primary tumors of CNS undergo metastasis