The role of chemoattraction in cancer metastases

It has long been unclear as to why particular cancers preferentially metast asize to certain sites. The possibilities usually discussed involve differe ntial survival and proliferation at these sites, or selective trapping with or without preferential homing. A recent report by Muller et al.((1)) prov ides evidence for preferential homing of breast cancer to metastatic sites. The findings indicate that the chemokine receptors CXCR4 and CCR7 are foun d on breast cancer cells and their ligands are highly expressed at sites as sociated with breast cancer metastases. This results in chemotaxis, or dire cted migration of tumor cells from their primary site via the circulation t o the preferential sites of metastases. The evidence for this model and its significance are reviewed here. (C) 2001 John Wiley & Sons, Inc.