Brain metastases from undiagnosed systemic neoplasms.

Fifty-six patients presenting with symptomatic brain metastasis but undiagnosed primary neoplasm were retrospectively studied. Metastases were almost equally solitary (57%) as multiple (43%), and 30% were cerebellar. Cerebral metastases were most often parietal (67%). Underlying cancers were diagnosed in 84% of patients, usually before death, with the remainder having equivocal or unknown primary cancers. Lung cancer was most common (68%), especially adenocarcinoma or small ("oat")-cell types, followed by gastrointestinal primary cancers (9%), cancers of the bladder and thyroid (2% each), melanoma (2%), and lymphoma (2%). Breast cancer was remarkably absent, perhaps due to its greater systemic involvement prior to brain metastasis, or its earlier detection on physical examination. Overall group survival rates were 55% (6 months) and 13% (12 months), and cerebellar and noncerebellar metastases had the same survival rate at 12 months. The diagnostic evaluation of these patients, often extensive and costly, should be individually tailored, as 23% had complaints or findings indicative of their underlying primary cancer. Overall, chest roentgenograms and computed tomograms of the chest were the tests of greatest yield, followed by computed tomograms of the abdomen and pelvis. A rationale for evaluation is presented.