Inclusion Criteria:

• Age 5 through 17 years of age (not yet reached their 18th birthday) at the time of entry into the study;
• Patient's parent or legal guardian available by telephone during the course of the study;
• Written informed consent (assent if applicable) and Health Insurance Portability and Accountability Act (HIPAA) authorization (if applicable) obtained from the patient's parent or legal guardian;
• Ability of the patient or patient's parent/guardian to comply with the requirements of the protocol;
• Currently receiving chemotherapy and/or radiation therapy for the treatment of cancer or have received chemotherapy in the past 12 weeks;
• If the subject's underlying cancer is a solid tumor, current status must be stable disease, partial response, or complete response to therapy; if the subject's underlying disease is a hematologic malignancy, current status must be in remission;
• Estimated life expectancy of >1 year; and
• Currently has no worse than mild to moderate immunosuppression (meets none of the exclusion criteria).

Exclusion Criteria:

• History of hypersensitivity to any component of FluMist, including egg or egg products, or monosodium glutamate;
• History of hypersensitivity to gentamicin;
• Close contact with a severely immunocompromised patient (e.g., a hematopoietic stem cell transplant patient, during those periods in which the immunocompromised patient requires care in a protective environment);
• History of Guillain-Barré syndrome;
• History of asthma;
• Use of aspirin or salicylate-containing products in the 30 days prior to study vaccination or expected receipt within the study duration;
• Use of anti-influenza medications (including amantadine, rimantadine, oseltamivir, and zanamivir) within 14 days prior to enrollment or expected receipt (unless medically indicated) during this study;
• Currently receiving inhaled steroid therapy;
• Receipt of immunoglobulin within the past 90 days;
• Receipt of stem cell transplant;
• Acute febrile [>100.0°F (37.8°C) oral] illness or acute respiratory illness, e.g., cough or sore throat, within three days prior to enrollment;
• Administration of any live vaccine within 30 days prior to enrollment or if receipt of another live vaccine is expected within 30 days after the vaccination in this study;
• Administration of any inactivated vaccine within two weeks prior to enrollment or if receipt of another inactivated vaccine is expected within two weeks after the vaccination in this study;
• Receipt of an investigational product studied under an investigational new drug (IND) within 10 days prior to study entry or expected receipt of such an investigational product within 10 days after study vaccination (Note: an investigational product not studied under an IND is allowed at the investigator's discretion);
• Pregnancy or, in biologically capable females (e.g., menses within the last year), not willing to agree to acceptable birth control for three months after study vaccination (for those biologically capable, a urine pregnancy test must be performed on the day of vaccination with a negative result);
• Female who is breastfeeding or lactating;
• Any condition or receipt of other medication that, in the opinion of the investigator, might interfere with the evaluation of the vaccine or interpretation of study results;
• At the study screening visit (within 16 days before study vaccination) a CD4+ T cell percentage of <15%;
• At study entry, an absolute neutrophil count greater than or equal to 500 cells/mm3;
• At study entry, less than 14 days from last high dose (> 2 mg/kg/day prednisone or equivalent) systemic corticosteroid therapy;