Central Nervous System Prophylaxis
Central nervous system (CNS) prophylaxis, also known as CNS sanctuary therapy, is treatment designed to keep the leukemia from spreading to the spinal cord and the brain. Because the chemotherapy delivered by mouth or intravenously enters the bloodstream but not the cerebral spinal fluid, leukemia cells can hide (or take sanctuary) in the CNS, escaping the drugs used to treat it. Either chemotherapy or radiation therapy may be used to kill these leukemic cells. Chemotherapy drugs are injected directly into the spinal fluid so the drugs affect only the CNS. Radiation therapy can also be effective in killing leukemia cells in the CNS.
Targeted Drug Therapy
Targeted drug therapy may be used to attack acute lymphocytic leukemia (ALL) when certain abnormalities (targets), such as the Philadelphia chromosome, have been discovered. In targeted drug therapy, specific drugs attack the cells with a particular abnormality (for example, imatinib (Gleevec) is used to target cells with the Philadelphia chromosome). Targeted drugs may be used in combination with standard chemotherapy.
Radiation therapy may be used in rare cases to treat ALL. Radiation therapy uses focused high-energy radiation to destroy cancer cells. In external beam radiation, a machine outside the body directs radiation toward the cancer. The healthy organs are protected by specially designed lead blocks. In internal radiation therapy, a radioactive substance is sealed inside needles, wires or seeds that are placed inside your body directly into or near the cancer.