Cerebrospinal fluid approach on neuro-oncology Estudo do líquido cefalorraquiano em neuro-oncologia

Diagnosis of central nervous system (CNS) involvement in neoplastic diseases is a major problem. Recent progresses in chemotherapies and targeted therapies have improved survival in cancer patients. In this context of better-controlled systemic disease, brain metastases (BM) are emerging as a new challenge for the oncologist1. BM are one of the most common neurologic complications of cancer. The incidence is 9%–17% based on various studies, although the exact incidence is thought to be higher2. The incidence is increasing with the availability of improved imaging techniques which aid early diagnosis, and effective systemic treatment regimens which prolong life, thus allowing cancer to disseminate to the brain. Lung cancer, breast cancer, and melanoma are the most frequent to develop brain metastases, and account for 67%–80% of all cancers. Some patients present with no known primary cancer diagnosis2,3. Cancer cells may invade the meninges through different pathways, depending on histology of the primary tumor. The most common route of metastasis resulting in leptomeningeal metastasis (LM) is probably the hematogenous spread to the arachnoid via the arterial circulation, mainly in hematological malignancies4,5. Vertebral and paravertebral metastases (particularly from breast and lung cancers), as well as head and neck cancers, may spread centripetally along peripheral or cranial nerves via the endoneu ral/ perineural route or along coassociated lymphatics or veins gaining access through the dural and arachnoidal sleeves of nerve roots (spinal roots, cranial nerves) and subsequently into the subarachnoid space 5,6. Direct spread from brain parenchyma that is in close to the cerebrospinal fluid (CSF) space has been described. These tumors may breach the subarachnoid or ventricular spaces and diffuse widely in the CSF. This manner of spread is particularly relevant with respect to primary brain tumors. Primary tumors arising in the meninges such as melanoma and some soft tissue sarcomas (e.g., malignant peripheral nerve sheath tumors) may secondarily spread to the CSF and disseminate2. Another way of CSF tumor spread is that resulting during invasive procedures, through ependymal or pial breach2,6.