Future perspectives: cancer metastases.

The sentinel lymph node (SLN) is the initial metastatic site for the majority of solid cancers. In some cases, cancer cells may bypass the SLNs and enter the vascular channels directly to spread to the systemic sites. Metastatic progression is an orderly process. During the process of metastasis, complex biochemical and molecular mechanisms are involved being subjected to the host influence, in particular, the immune system. With more detailed understanding of the genomic and molecular characteristics of cancer both from the primary site and its metastases, the pathways of cancer growth and spread within the cancer microenvironment may be further elucidated.