Cancer metastasis

Metastasis is the cause of almost all cancer-related deaths. It is an extremely complex, multistep process defined as the spreading of cancer cells from their primary site to distant tissues. Once metastasis occurs it causes catastrophic damage to the critical organs, which is ultimately detrimental to patients. Collective efforts of many scientists have revealed the underlying molecular mechanisms of metastasis by a considerable extent, but there is still a colossal job to be undertaken by researchers to solve this life-threatening health problem. In this chapter, metastasis is explained by focusing on underlying molecular pathways. We define the steps that a cancer cell needs to climb in order to metastasize and discuss the significant molecular actors aberrantly regulated during this process. First, we outline how these molecules are deregulated in cancer cells in order to circumvent natural barriers against metastasis. Then, we give a molecular explanation on why some cancer types metastasize to certain organs. Lastly, we look into recent therapeutic trials, which involve targeting of pathways in the metastatic cascade (Figure 18.1).