In primary brain tumor, cerebrospinal fluid protein level is elevated in up to 70% of patients and cell count in about 30% of cases. One or the other is abnormal in 65%–80% of cases. Electroencephalogram (EEG) is abnormal in about 70%–75% of patients (literature range, 70%–92%), brain scan in about 80%–85% (65%–96%), and CT in about 90%–95% (85%–100%). Therefore, CT scan (or magnetic resonance imaging [MRI]) is clearly the best single test for primary brain tumor (or any space-occupying brain lesion), whereas EEG adds little, if anything, to CT or brain scan information. About 15%–25% (range, 4%–37%) of brain tumors are metastatic (“e condary”). The most common site of origin is lung (about 40% of metastatic brain tumors; literature range, 35%–60%). Next is breast (about 25%; range, 20%–30%); third is probably melanoma (about 10%–15%) or kidney (about 10%). The GI tract (including pancreas) contributes about 5%, and the remainder is shared by various primary sites.