Stereotactic Radiosurgery in Treating Participants with Brain Metastases and Studying Their Neurocognitive Decline

Inclusion Criteria

• Age >= 18 years
• Eastern Cooperative Oncology Group (ECOG) performance score of 2 or better / Karnofsky performance status score of 50-60 or better.
• Biopsy-proven non-hematopoietic malignancy, except for germ cell cancer. Small cell lung carcinoma is eligible for this study.
• Six or more metastases on diagnostic or treatment planning imaging, which include either computed tomography (CT) brain (with contrast) or magnetic resonance (MR) brain (with or without contrast) imaging.
• Largest tumor =< 4 cm.
• No prior stereotactic radiosurgery (SRS) to the lesions which will be treated on protocol.
• Women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry, and for the duration of protocol treatment and for 90 days following completion of therapy. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately.
• A female of child-bearing potential is any woman (regardless of sexual orientation, marital status, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria: * Has not undergone a hysterectomy or bilateral oophorectomy; or * Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months).
• Ability to understand and the willingness to sign a written informed consent.

Exclusion Criteria

• Prior whole brain radiotherapy.
• Patients with leptomeningeal metastasis. * NOTE: For the purposes of exclusion, leptomeningeal metastasis (LMD) is a clinical diagnosis, defined as positive cerebrospinal fluid (CSF) cytology and/or equivocal radiologic or clinical evidence of leptomeningeal involvement. Patients with leptomeningeal symptoms in the setting of leptomeningeal enhancement by imaging (MRI) would be considered to have LMD even in the absence of positive CSF cytology, unless a parenchymal lesion can adequately explain the neurologic symptoms and/or signs. In contrast, an asymptomatic or minimally symptomatic patient with mild or nonspecific leptomeningeal enhancement (MRI) would not be considered to have LMD. In that patient, CSF sampling is not required to formally exclude LMD, but can be performed at the investigator’s discretion based on level of clinical suspicion
• Patients with life expectancy < 4 months.
• Psychiatric illness/social situations that, in the opinion of the investigator, would limit compliance with study requirements.
• Subjects must not be pregnant or nursing due to the potential for congenital abnormalities and the potential of this regimen to harm nursing infants.