DEMOGRAPHICS OF BRAIN METASTASIS

Brain metastases are the most common intracranial tumor, significantly outnumbering primary brain tumors. The apparent increase in the ratio of brain metastases to primary tumors maybe the result of a number of factors, including the possibility of a CNS ''pharmacologic sanctuary ,'' an aging population, and improved imaging studies. Among adults, t he most common origins of brain metastasis include primary tumors of t he lung, breast, skin (melanoma), and gastrointestinal tract. Among pa tients under 21 years of age, brain metastases most often arise from t he sarcomas and germ cell tumors.