-In this retrospective study, 47 patients with clinical diagnosis of central nervous system metastases of breast cancer were evaluated by computerized tomography (CT), magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) examination. The patients were divided in 2 groups: 1, without leptomeningeal neoplasm and 2, with leptomeningeal neoplasm. In the group 2, the time interval between the primary disease and the central nervous system metastasis as well as the survival time were shorter than in group 1 (40 and 4.3 months in group 2 versus 57 and 10 months respectively, in group 1). In both groups the most common neurological symptoms and signs were intracranial hypertension and motor deficits. The most sensitive diagnostic methods were CT and MRI in group 1, and the CSF examination in group 2. The use of the tumor markers CEA and CA-15.3 in the routine examination of CSF showed promising results, mainly in leptomeningeal forms.KEY WORDS: central nervous system metastasis, breast cancer, cerebrospinal fluid, tumor markers. Metástases do sistema nervoso central por câncer de mama: estudo clínico-laboratorial em 47 pacientesRESUMO -Neste estudo retrospectivo, 47 pacientes com diagnóstico clínico de metástases do sistema nervoso por câncer de mama foram avaliados por tomografia computadorizada (TC), ressonância nuclear magnética (RNM) e por exames do líquido cefalorraqueano (LCR). Os pacientes foram divididos em 2 grupos: 1, sem neoplasia leptomeníngea e 2, com neoplasia leptomeníngea. No grupo 2 o intervalo de tempo entre a doença primária e o comprometimento do sistema nervoso e o tempo de sobrevida foram menores do que no grupo 1 (40 e 4,3 meses no grupo 2 versus 57 e 10 meses respectivamente, no grupo 1). Os sinais e sintomas neurológicos mais frequentes foram hipertensão intracraniana e déficits motores. Os exames mais sensíveis para o diagnóstico foram a TC e RNM no grupo 1 e o exame do LCR no grupo 2. O uso dos marcadores CEA e CA-15.3 na rotina do LCR mostrou resultados promissores, particularmente nas formas leptomeníngeas. PALAVRAS-CHAVE: metástases no sistema nervoso central, câncer de mama, líquido cefalorraqueano, marcadores tumorais.Autopsy studies show that central nervous system (CNS) metastasis of breast cancer occur in nearly 30% of the patients but only 10% are diagnosed or suspected clinically before death 1,2 . Recent epidemiological data indicate that the incidence of CNS metastasis has been increasing in the last two decades; this could be explained by the increased survival of the breast cancer patients nowadays 3,4 . The clinical presentation of these patients is pleomorphic, depending on the localization of the lesions, meningeal involvement and paraneoplastic syndromes, as well as on therapeutic complications 2,5 . Specific and sensitive diagnostic tools, both clinical and laboratorial, must be familiar to the neuro-oncologist.