Inclusion Criteria:

• Ability to understand and the willingness to sign a written informed consent document.
• Brain metastases from histologically confirmed extracranial cancer or previously confirmed intracranial carcinoma. Carcinoma must be staged using the American Joint Committee on Cancer (AJCC) staging criteria version 6.
• Morphologically well-defined tumor mass on computed tomography (CT)/magnetic resonance imaging [MRI] (largest diameter less than 40 mm) after resection.
• Intracranial mass or masses ≤ 4 cm in greatest diameter. Patients with multiple masses will be eligible if their radiosurgery treatment time is expected to last less than one hour (typically a maximum of 6 lesions).
• Standard institutional radiotherapeutic treatment is stereotactic radiosurgery delivered using bite-plate localization.
• Greater than or equal to 21 years of age. Pediatric subjects represent a minority of patients who otherwise meet the eligibility criteria. Inclusion of children in a different study would be considered if therapy is found to be effective in adults and not as part of this trial because the safety of 2DG in children has not been investigated.
• Karnofsky greater than or equal to 70% at time of screening
• Life expectancy of greater than 3 months

• Subjects must have normal organ and marrow function as defined below:

  • serum glucose < 200 mg/dl
  • hemoglobin A1C (HbA1c) < 8.5 %
• Contraceptive use in men and women of childbearing potential prior to, and for the duration of, this study. The teratogenic effects of ionizing radiation are well documented, and 2DG has the potential for teratogenic or abortifacient effects.
• Nursing of infants must be suspended during the study. There is an unknown but potential risk for adverse events in infants nursing from patients treated with 2DG, therefore breastfeeding must be discontinued for the duration of the study.
• Ability to ingest 50 ml of fluid either by mouth or feeding tube.
• Inclusion of women and minorities: Both men and women of all races and ethnic groups are eligible for this trial.

Exclusion Criteria:

• Subjects with diabetes mellitus, elevated HbA1c or elevated blood glucose.
• Subjects requiring a headring ('halo') immobilization for standard stereotactic localization. Patients with metastases adjacent to optic chiasm, optic nerve or other radiosensitive tissue necessitating the accuracy of a headring will be excluded.
• Subjects must not be receiving any other investigational agents.
• Subjects with a history of myocardial infarction in the past year and/or dependent on beta-adrenergic blocking agents.
• Subjects with an uncontrolled seizure disorder.
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements.
• Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the nursing mother with 2DG, breastfeeding must be discontinued while the nursing mother is treated.
• Pregnant women are excluded from this study. The teratogenic effects of ionizing radiation are well documented, and 2DG has the potential for teratogenic or abortifacient effects. Women of childbearing potential must have a negative pregnancy test result immediately prior to the study and should they become pregnant or suspect that they are pregnant during the study, they must inform their treating physicians immediately.
• Inclusion of prisoners and other vulnerable populations: Prisoners and other vulnerable populations, such as children, will not be enrolled.