Metastasis is the spread of a disease from one organ or part to another non-contiguous organ or part. Only malignant tumor cells and infections have the capacity to metastasize. Cancer cells can "break away" from a primary tumor, penetrate into lymphatic and blood vessels, circulate through the bloodstream, and grow in a distant focus (metastasize) in normal tissues elsewhere in the body. Metastasis is considered a hallmark of malignancy. All tumors can metastasize albeit to varying degrees, barring a few exceptions (eg. Glioma and Basal cell carcinoma never metastasize). When cancer cells spread to form a new tumor, it is called a secondary, or metastatic tumor, and its cells are like those in the original tumor. This means, for example, that if breast cancer spreads (metastasizes) to the lung, the secondary tumor is made up of abnormal breast cells (not abnormal lung cells). The disease in the lung is then called metastatic breast cancer (not lung cancer). Only malignant tumor cells and infections have the capacity to metastasize. This new book presents the latest research in the field from around the world.