The simplest definition of hematological cancers is that they are cancers which arise from a single blood cell. Since all blood cells are produced by a process called hematopoiesis (“heme” comes from the Greek word haema or “ α ιc μα” for blood and “ π ο í ησιc ” or poiesis means creation or formation), cancers such as leukemias, lymphomas, and myelomas are often referred to as blood cancers. The cancer type usually refers to the organ or the specific type of cell where cancer originates. To distinguish blood cancer from other forms of cancers, they are sometimes referred to as “liquid tumors” since they typically do not form lumps or masses (“tumors”). In contrast, cancers arising from all other cells, which typically form masses, are called “solid tumors.”