This phase II trial studies whether low dose dexamethasone works as well as standard dose dexamethasone to reduce brain swelling after brain surgery in patients with primary brain tumors or cancer that has spread from other places in the body to the brain (metastatic). Surgery is an important part of the treatment of brain tumors; however, it results in injury to surrounding brain tissue, leading to brain swelling. Dexamethasone is effective for controlling the swelling of the brain; however, dexamethasone can cause many unwanted side effects. To minimize the side effects of dexamethasone, the lowest dose needed to control swelling of the brain should be used. This research study is assessing the safety of using a lower than standard dose of dexamethasone after the surgery to control brain swelling.

PRIMARY OBJECTIVES:

I. Assess the feasibility of administering lower doses of dexamethasone post-operatively in patients who have mild to moderate cerebral edema pre-operatively.

II. Describe the toxicity profile associated with post-operative lower doses and standard doses of dexamethasone, separately.

SECONDARY OBJECTIVES:

I. Descriptively assess the consistency between the quantitative data produced by strategically acquired gradient echo (STAGE) and qualitative assessments of changes in cerebral edema on serial fluid-attenuated inversion recovery (FLAIR) images.

II. Quantitatively assess changes in the volume of cerebral edema post-operatively in participants on Arm 1 (standard dose) and Arm 2 (low dose).

EXPLORATORY OBJECTIVE:

I. Describe changes in the volume of cerebral edema between pre-operative and post-operative day 1 brain magnetic resonance imaging (MRIs) in Arm 1 (standard dose) and Arm 2 (low dose) participants, separately.

OUTLINE: Patients are randomized to 1 of 2 arms.

ARM I: Patients receive standard dose dexamethasone orally (PO) every 12 hours (q 12 h) for 3 days. On the day of surgery, patients receive standard dose dexamethasone intravenously (IV) before and after the surgery. Patients receive standard dose dexamethasone IV q 12 h on days 1-3 post surgery and tapered dexamethasone PO q 12 h on days 4-14 in the absence of disease progression or unacceptable toxicity. Additional doses of dexamethasone are given if needed.

ARM II: Patients receive lower dose dexamethasone PO q 12 h for 3 days. On the day of surgery, patients receive lower dose dexamethasone IV before and after the surgery. Patients receive lower dose dexamethasone IV q 12 h on days 1-3 post surgery and tapered dexamethasone PO q 12 h on days 4-14 in the absence of disease progression or unacceptable toxicity. Additional doses of dexamethasone are given if needed.

After completion of surgery, patients are followed up after 30 days.

Inclusion Criteria:

• Participant is 18 years or older.

• Participant has a Karnofsky Performance Status of >= 60%.

• Participant has a primary or metastatic brain tumor(s).

• Participant can have newly diagnosed or recurrent brain tumor(s).

• If a participant is requiring more than 3 mg orally every 12 hours (q 12 h) of dexamethasone at the time of signing the consent form, it is anticipated by the neurosurgeon that the participant will be able to taper down their dose of dexamethasone to 3 mg orally q 12 h by 3 days before the surgery.

  • (Note: If the patient is not able to decrease their dose of dexamethasone to 3 mg orally q 12 h 3 days before surgery, the patient will not be allowed to participate in the study.)

• Participant must have less than 10 mm of midline shift seen on pre-op brain magnetic resonance imaging (MRI).

• The neurosurgeon anticipates being able to perform a gross total resection of tumor.

• Participant is not planning to participate in another clinical trial during the study period.

• There is no limit to the number of prior therapies for enrollment in this study.

• All participants must have the ability to understand and the willingness to sign a written informed consent.

Exclusion Criteria:

• Participant is unable to undergo a brain MRI.
• Participant is unable to tolerate dexamethasone.
• Participant has a chronic or active viral infection of the central nervous system (CNS).
• Participant has a coagulopathy or bleeding disorder.
• Participant has an uncontrolled illness including ongoing or active infection.
• Participant has another active malignancy.
• A patient has a serious medical or psychiatric illness that could, in the investigator's opinion, potentially interfere with the safety monitoring requirements and completion of treatment according to this protocol.