[Brain metastasis and the carcinoembryonic antigen]

Neurological complications have a notable repercussion on the quality of life of patients with systemic cancer, and can even become the direct cause of death. The complication that causes most concern is undoubtedly brain metastasis, because of its difficult management and because there has been an upward tendency in its incidence in the last few years.

The aim of this study is to provide a review of the literature about brain metastases and, more particularly, about the carcinoembryonic antigen (CEA) as a marker of these pathologies.

In general it is reckoned that 60% of all brain metastases start from the lung and most of them are multiple when they are diagnosed, which suggests a possibly mistaken staging of these patients. The carcinoembryonic antigen is the prototypical tumour marker, and it is usually found in higher concentrations in the cerebrospinal fluid of patients with metastatic tumours in the central nervous system. As the CEA goes through the blood brain barrier, it behaves in a similar way to IgA due to their having homologous molecular weights. This allows us to employ the same hyperbolic distribution curve that is used as a reference for lgA to distinguish between intrathecally synthesized CEA and that which diffuses from the systemic circulation.

In spite of the progress that has been obtained with the new therapies, brain metastases continue to have a poor prognosis. Hence, there is a need to identify new tumour markers that allow a diagnosis to be established before the clinical methods and presentations.