Investigations of the mechanisms of metastatic spread of naturally occurring neoplasms.

Much of the effort of this laboratory in recent years has been directed towards developing a reliable protocol for the experimental analysis of factors affecting metastatic spread from naturally occurring (i.e. not transplanted) neoplasms. The objective of this has been to develop a data base on the variations in metastatic behaviour between spontaneously arising neoplasms and to examine the tumour-specific and host-specific mechanisms accounting for this. This paper details the experimental technique and underlying conceptual basis which have been developed for reproducible investigations of this subject. It also reviews our conclusions from such work on the role in metastatic spread of tumour cell surface properties, collagenase secretion, microenvironmental effects on tumour cell growth in various organs, tumour macrophage content, and degree of cell shedding into the bloodstream.