All patients will have at least one lumbar puncture (spinal tap) during the first cycle of induction. This is done to check the status of the disease and to give drugs to help prevent side effects, called intrathecal chemotherapy (methotrexate and/or cytarabine). Intrathecal chemotherapy is given by injecting the chemotherapy directly into the cerebrospinal fluid. The standard for patients is to receive 8 of these treatments. On this study, you will only receive the drug 1 time unless the study doctor thinks it is in your best interest to receive additional doses. Then you may receive it up to 8 times.