Leukapheresis can be used in the context of cancer for several reasons. It is often employed to reduce a high white blood cell count in patients with certain types of leukemia, such as chronic myeloid leukemia (CML) or acute lymphoblastic leukemia (ALL). By lowering the white blood cell count, leukapheresis can help alleviate symptoms and prevent complications such as leukostasis, which can cause blood flow issues and organ damage.