Overview of metastasis assays.

During tumor progression, cells acquire genetic and proteomic changes as they transform from normal to hyperplastic, through dysplasia, to carcinoma in situ, and finally to invasive and metastatic. The time course of progression may extend as far back as 10 years prior to diagnosis. Discerning the mechanism whereby tumor cells execute metastatic dissemination may provide the foundation necessary for successful treatment of the disease. For example, direct genetic evidence has linked in situ breast cancer to invasive carcinoma of the breast supporting the generally accepted assumption that carcinoma in situ of the breast is a clonal expansion of hyperproliferating cells. This in turn may provide a more comprehensive and/or functionally directed target strategy for intervention and prevention of breast cancer. This overview provides a picture of the processes related to metastasis and the experimental approaches used to study these processes.