Biomarkers in Blood Samples From Young Patients With Newly Diagnosed Brain Tumors Undergoing Standard Radiation Therapy and Chemotherapy

OBJECTIVES:

Primary

- Evaluate the fraction of peripherally circulating T-regulatory cells (T_regs) in
pediatric patients with newly diagnosed medulloblastoma and compare it to the levels
found in a control group of patients undergoing craniectomy for Chiari malformation.

- Evaluate the longitudinal effects of standard radiotherapy and chemotherapy regimens on
the overall population of lymphocytes as well as the fraction of T_reg cells in patients
with medulloblastoma.

Secondary

- Determine the baseline fraction of T_reg cells in those with non-medulloblastoma
posterior fossa tumors compared to levels found in patients undergoing decompression for
Chiari malformation.

OUTLINE: This is a multicenter study.

Patients with Chiari malformation and patients with posterior fossa tumor undergo standard
surgery. Patients with posterior fossa tumor also receive standard radiotherapy and
chemotherapy.

Blood samples are collected at baseline and periodically to measure the level of circulating
T-regulatory cells.

DISEASE CHARACTERISTICS:

- Meets 1 of the following criteria:

- Histologically confirmed posterior fossa tumor

- Newly diagnosed disease

- Medulloblastoma OR non-medulloblastoma (pilocytic astrocytoma, ependymoma,
atypical rhabdoid tumor, or others)

- Scheduled to undergo craniotomy and tumor resection

- Chiari malformation

- Requires craniectomy for decompression

- No secondary decompression

PATIENT CHARACTERISTICS:

- No unexplained febrile illness

- No active infection

- No autoimmune disorders such as inflammatory bowel disease, juvenile rheumatoid
arthritis, or systemic lupus erythematosus

- No other immunosuppressive disorders (e.g., HIV infection)

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics