Preventative Trial of Difluoromethylornithine (DFMO) in High Risk Patients With Neuroblastoma That is in Remission

Inclusion Criteria: * Age: 0-21 years at the time of diagnosis. * Diagnosis: histologic verification at either the time of original diagnosis or a previous relapse of high risk neuroblastoma. * Disease Status: Neuroblastoma that is in remission * First dose of study medication must be greater than 30 days from completion of cytotoxic and antibody therapy and less than 120 days from previous therapy * A negative serum or urine pregnancy test is required for female subjects of child bearing potential (onset of menses or ≥13 years of age). * Both male and female post-pubertal study subjects need to agree to use one of the more effective birth control methods during treatment and for six months after treatment is stopped. These methods include total abstinence (no sex), oral contraceptives ("the pill"), an intrauterine device (IUD), levonorgestrel implants (Norplant), or medroxyprogesterone acetate injections (Depo-provera shots). If one of these cannot be used, contraceptive foam with a condom is recommended. * Absolute Neutrophil Count (ANC) \> 500/μl and platelet count \>50,000/μl * Organ Function Requirements: Subjects must have adequate liver function as defined by: * Aspartate Aminotransferase (AST) and Alanine transaminase (ALT) \<10x upper limit of normal * Serum bilirubin must be ≤ 2.0 mg/dl * Serum creatinine based on age/gender * Informed Consent: All subjects and/or legal guardians must sign informed written consent. Assent, when appropriate, will be obtained according to institutional guidelines Exclusion Criteria: * Lansky score \< 60% * Body Surface Area (BSA) (m2) of \<0.25 * Investigational Drugs: Subjects who are currently receiving another investigational drug are excluded from participation. * Anti-cancer Agents: Subjects who are currently receiving other anticancer agents are not eligible. Subjects must have fully recovered from the effects of prior chemotherapy (hematological and bone marrow suppression effects). * Infection: Subjects who have an uncontrolled infection are not eligible until the infection is judged to be well controlled in the opinion of the investigator. * Subjects who, in the opinion of the investigator, may not be able to comply with the safety monitoring requirements of the study, or in whom compliance is likely to be suboptimal, should be excluded.