This study will investigate the safety, tolerability, and effectiveness of changing the order of receiving radiation therapy for treating brain cancer. The investigators hope that changing the sequence of radiation therapy will lower the risk of cancer spreading throughout your spinal fluid, which covers your brain and spinal cord.

This study will attempt to determine the maximum tolerated dose of pre-operative stereotactic radiosurgery (SRS) in the treatment of brain metastases. Patients will be placed in one of two dose groups based on index tumor size, and dose will be adjusted according to presence or absence of dose limiting toxicity (DLT).

Group A: Index Tumor > 2 cm and up to 4 cm in maximum diameter Group B: Index Tumor > 4 cm and up to 6 cm in maximum diameter

Dose escalation or de-escalation will be conducted via a modified 3+3 method at the following levels. Group A will start at dose level II. Group B will start at dose level I.

Dose Level I: 12 Gy Dose Level II: 15 Gy

Inclusion Criteria:

• All subjects must have history of histologically confirmed malignancy. Brain biopsy is not required unless diagnosis is judged to be in doubt by the treating physician.
• Newly diagnosed brain metastases (four or fewer by post-contrast MRI obtained within six weeks of study entry)
• At least one brain metastasis (index tumor) must be within 2-6 cm in maximum diameter and deemed appropriate for surgical resection by the treating neurosurgeon.
• Karnofsky performance status (KPS) of greater than or equal to 60
• Age greater than 19
• Life expectancy greater than 12 weeks
• Subjects given written informed consent

Exclusion Criteria:

• Patients with small cell lung cancer and lymphoma are ineligible.
• More than four metastases by baseline post-contrast MRI
• Prior whole brain radiation therapy
• Insufficient recovery from all active toxicities of prior therapies
• Subjects who are deemed to be poor surgical risks by the treating neurosurgeon because of medical comorbidities
• Pregnant or nursing women
• Women of childbearing potential who are not using an effective method of contraception are excluded. Women of childbearing potential must have a negative urine or serum pregnancy test within 24 hours prior to administration of SRS.