RATIONALE: Studying levels of tumor DNA in the samples of blood from patients with cancer may help doctors find out whether the cancer has grown and how much.

PURPOSE: This laboratory study is comparing levels of tumor DNA with MRI and CT scan findings to measure cancer growth in patients with grade III or grade IV malignant glioma.

OBJECTIVES:

• Correlate changes in the level of serum tumor-specific DNA over time with changes in brain tumor size as measured by serial MRI or CT scans in patients with grade III-IV malignant gliomas.

OUTLINE: This is a multicenter study.

Blood samples are collected from patients at baseline and every 2 months thereafter. Tumor and nontumor plasma is extracted. Plasma samples are analyzed by polymerase chain reaction (PCR) to assess the p16_ink4a, p73, and O ^6-MGMT gene promoter methylation profile. Quantitative realtime PCR is performed on samples with tumor-specific DNA to determine the plasma concentrations of each methylated tumor-specific gene and the total plasma tumor-specific DNA concentration. Patients also undergo MRI or CT scans every 2 months.

PROJECTED ACCRUAL: A total of 60 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• Histologically confirmed malignant brain tumor

  • One of the following grade III or IV supratentorial gliomas:

    • Anaplastic astrocytoma
    • Anaplastic oligodendroglioma
    • Glioblastoma multiforme

• Newly diagnosed or recurrent disease

• Planning to undergo anticancer therapy on a New Approaches to Brain Tumor Therapy (NABTT) Consortium clinical trial

PATIENT CHARACTERISTICS:

• Karnofsky performance status 60-100%

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics