COPD Leukemia is a cancer of the blood or bone marrow and is characterized by an abnormal proliferation (production by multiplication) of blood cells, usually white blood cells (leukocytes). Leukemia is a broad term covering a spectrum of diseases. In turn, it is part of the even broader group of diseases called hematological neoplasms. GIOSTAR scientists have successfully differentiated the blood stem cells, which can change the defective blood stem cells of the body and make healthy blood cells to remove the cancerous blood cells.