Mononuclear phagocytes in the control of primary and secondary tumor growth.

In a variety of defined experimental host/tumor situations there is now considerable evidence that mononuclear phagocytes are critically involved in the control of tumor cell nidation and their establishment as primary tumors. The factors which determine secondary tumor cell spread and the establishment of metastases are clearly complex and make it highly unlikely that tumor cell dissemination is under the control of a single host defense mechanism. Nonetheless, findings in various experimental models suggest a critical role for mononuclear phagocytes in the surveillance of tumor cell dissemination.