Principles of radiotherapy of neoplastic meningosis

Leptomeningeal metastasis as initial manifestation of signet ring colorectal adenocarcinoma: a case report with review of literature

Leptomeningeal carcinomatosis (LMC) is an exceedingly rare event especially as a first manifestation of an occult primary colorectal cancer and even when there is a known history of malignancy. Sensorineural hearing loss is by itself an unusual isolated presentation of LMC with unsolved pathophysiology in this setting. In this paper, we report such a case and review the literature for similar cases, focusing on postulated mechanisms of spread. In view of the poor prognosis they carry, we highly recommend that physicians be aware of the risk of rare metastasis from colorectal adenocarcinoma in order to establish an early confirmative diagnosis.

Leptomeningeal neoplasms

Leptomeningeal metastasis is becoming an increasingly important late complication of cancer as survival from systemic disease increases, and due to the fact that many novel cancer drugs fail to achieve therapeutic concentrations in the central nervous system. It occurs when neoplastic cells enter cerebrospinal fluid (CSF) pathways, causing diffuse infiltration of the subarachnoid space of the brain and spinal cord. Definitive diagnosis is established by the demonstration of malignant cells in the CSF. However, in certain circumstances the presence of leptomeningeal enhancement on brain or spinal MRI may be sufficient to make the diagnosis. Early diagnosis and aggressive treatment may delay neurologic progression and can lead to prolonged survival and improvement of neurologic function in certain patients. The prognosis depends on the underlying malignancy but is often poor, with a median survival of 4 months, and most treatment interventions are palliative. Nevertheless, some patients respond to treatment, and some survive beyond 1 or 2 years after diagnosis. Areas of radiographic bulky disease or symptomatic tumor should receive radiotherapy. Intrathecal chemotherapy is most effective in patients with lymphoma, leukemia, or breast cancer and without evidence of bulky disease on neuroimaging. Intrathecal chemotherapy requires normal CSF flow, and the most commonly used agents are methotrexate, cytarabine, and thiotepa. In lieu of intrathecal therapy, systemic chemotherapy may occasionally be indicated in select patients in part based on its ability to penetrate into bulky disease. When hydrocephalus occurs, ventriculoperitoneal shunting frequently leads to rapid clinical improvement. There is hope that progress in diagnostic modalities and the development of more effective intrathecal antineoplastic drugs may decrease neurologic morbidity and improve quality of life and survival.

Metastatic neurologic complications of non-Hodgkin's lymphoma

Neurologic complications of non-Hodgkin's lymphoma represent challenging diagnostic and therapeutic issues. Leptomeningeal, epidural, and brain metastases are the most common neurologic complications, and each is associated with a poor prognosis. However, early recognition and intervention often result in improved quality of life and, for a subset of patients, an opportunity for longer survival.

Radiation therapy for leptomeningeal cancer

Radiotherapy has multiple roles in the treatment of leptomeningeal cancer. While it is uncommon for patients to experience regression of neurologic deficits due to leptomeningeal cancer, focal radiotherapy often provides significant palliation of pain, increased intracranial pressure and other focal symptoms. Focal radiotherapy may also be used to eliminate blockages of cerebrospinal fluid (CSF) and allow for safe administration of intrathecal chemotherapy. Craniospinal irradiation (CSI) is most often used as prophylaxis for patients at high risk of leptomeningeal tumor dissemination, but may result in symptom palliation and prolonged disease control for patients with active leptomeningeal tumor.

Leptomeningeal Neoplasms

Leptomeningeal metastases are a late, devastating complication of systemic cancer that typically occurs in conjunction with other systemic relapse. The most common neurologic symptoms include headache, altered mentation, and difficult walking. Diagnosis is established by neuroimaging and cerebrospinal fluid analysis. The prognosis is poor with a median survival of 6 to 8 weeks; therefore most treatment interventions are palliative. Radiotherapy should be given to sites of bulky or symptomatic tumor. Intrathecal chemotherapy is most effective in patients with lymphoma, leukemia, and breast cancer. Systemic chemotherapy may be more effective in treating bulky leptomeningeal tumor. Ventriculoperitoneal shunting can be extremely useful in patients with obstructive hydrocephalus or increased intracranial pressure.