Do generalized metastases occur directly from the primary

Abstract Based on 4728 autopsy reports from Roswell Park Memorial Institute and a relatively sophisticated statistical technique for testing hypotheses about processes of dissemination, an overall survey of primary and metastatic cancer sites has been made. The principal results are as follows: (1) Ordinarily the dissemination of metastatic cancer does not occur directly from the primary site. (2) A multi-step or ‘cascade' process is involved. (3) The ‘cascade' involves one or more intermediate sites—typically lung or liver but sometimes bones or other organs. (4) The specific steps in the cascade differ from one primary site to the next, but the general pattern is a multi-step process. (5) Once generalization occurs, the distinctions between primary sites diminishes and the generalized disease might be considered as a separate entity. These findings have immediate implications for research and therapy.