Leptomeningeal carcinomas
Leptomeningeal carcinomas, also known as leptomeningeal carcinomatosis or leptomeningeal metastasis, occur when cancer cells spread to the central nervous system (CNS), affecting areas such as the brain and spinal cord. This condition is primarily a complication of existing metastatic cancers, with breast, lung, and gastrointestinal cancers being the most common sources. The growth of cancer in the subarachnoid space, where cerebrospinal fluid circulates, allows for the free movement of cancer cells throughout the CNS. Symptoms can vary significantly based on the location of the cancer but often include headaches, nausea, cognitive changes, and issues with vision or balance, reflecting the involvement of cranial and spinal nerves.
Diagnosis typically involves a series of lumbar punctures to collect cerebrospinal fluid, along with imaging scans to identify affected areas. Unfortunately, leptomeningeal carcinoma is generally associated with advanced cancer stages, and treatment options are limited, focusing on symptom management and prolonging survival through radiation and chemotherapy. The prognosis for individuals diagnosed with this condition is often poor, with an average survival time of only a few months. Awareness of leptomeningeal carcinomas is crucial for those affected by metastatic cancer, as early detection and management may influence outcomes.
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Leptomeningeal carcinomas
ALSO KNOWN AS: Leptomeningeal carcinomatosis (LC), leptomeningeal metastasis (LM), leptomeningeal seeding, carcinomatous meningitis, neoplastic meningitis, leptomeningeal disease (LMD)
RELATED CONDITIONS: Metastasized cancers, most often of the breast, lung, and gastrointestinal tract; melanoma; lymphoma
DEFINITION: Leptomeningeal carcinoma is the growth of cancer in the central nervous system (brain and spinal cord) as a result of the metastasis of a primary cancer.
Risk factors: People develop leptomeningeal carcinoma because they have another type of cancer that spreads (metastasizes) to the central nervous system. Small-cell lung cancers, malignant melanoma, cancers of the gastrointestinal tract, cancers of the blood, and breast cancer are the most likely to into leptomeningeal carcinoma.
Etiology and the disease process: The central nervous system (CNS) consists of the brain and spinal cord. Three membranes cover the brain. The pia mater is a thin, delicate membrane that lies tightly on top of the brain and spinal cord cells. The arachnoid mater is the middle membrane surrounding the CNS. It fits loosely, creating space between the pia and arachnoid mater. This space is called the subarachnoid space.
The subarachnoid space is filled with cerebrospinal fluid (CSF). This fluid brings nutrients to the nerve cells, removes wastes, and cushions the CNS during movement. Once cancer cells enter the CSF, they can move freely to any CNS location. Leptomeningeal carcinoma develops in the subarachnoid space, usually in multiple locations. The outer membrane, or dura mater, does not play a role in this cancer.
Leptomeningeal carcinoma develops secondary to another type of cancer, almost always after the original cancer has been treated and then returned. Blood cancers and cancer cells that solid tumors have shed travel through the circulatory system and enter the CSF, often by burrowing through the wall of a blood vessel. This process is called leptomeningeal seeding. Once in the CSF, the cancer cells multiply. They are transported through the CSF and eventually attach to nerve cells in the brain and spinal cord, where they grow into flat sheets of tissue (often in the brain) or cells. The cancer cells also spread along nerves emerging from the spinal column.
Incidence: The disease is likely underdiagnosed, but studies indicate around 5 percent of people with cancer develop leptomeningeal carcinoma. An estimated 20 percent are found to have evidence of the disease upon autopsy. Leptomeningeal carcinoma can occur in adults and children. Incidence varies by cancer type. Up to 11 percent of individuals with small-cell lung cancer (SCLC) develop leptomeningeal carcinoma. In comparison, as few as 1 percent of individuals with acute lymphocytic leukemia (ALL) may develop the disease.
Symptoms: Symptoms depend on where the leptomeningeal carcinoma is located. Masses of cells may interrupt the flow of CSF and cause an increase in pressure in the brain. Symptoms associated with leptomeningeal carcinoma in the brain include headaches accompanied by nausea and vomiting, disturbances in balance and gait, memory problems, and behavioral changes.
Symptoms associated with leptomeningeal carcinoma along the cranial nerves (twelve pairs of nerves that originate in the brain and enervate the head, neck, and upper chest) include double vision or other vision problems, hearing loss, problems swallowing, and dizziness. These are the most common symptoms in more than 90 percent of patients. More than one cranial nerve is usually involved, so multiple symptoms are present in the same individual.
Symptoms associated with leptomeningeal carcinoma in nerves that originate in the spine include neck and back pain, incontinence, and leg weakness. Patients often have a combination of symptoms because multiple sites are affected.
Screening and diagnosis: Multiple lumbar punctures aid in diagnosis. In a lumbar puncture, a small amount of CSF is withdrawn from the subarachnoid space using a needle. Since the physician can not be sure where the leptomeningeal carcinoma is located, the likelihood of correctly diagnosing it with a single lumbar puncture, is only about 50 percent. When lumbar puncture is repeated thrice at different sites, the possibility of making a positive diagnosis increases to almost 90 percent. Diagnosis also involves contrast-enhanced imaging scans (magnetic resonance imaging, computed tomography, and myelography) to identify the location of the leptomeningeal carcinoma for treatment.
Because leptomeningeal carcinoma is the result of metastasis of a primary cancer, it is, by definition, stage IV cancer.
Treatment and therapy: The goal of treatment is to prevent the development of additional symptoms and prolong the patient's survival. Treatment options are often limited because leptomeningeal carcinoma is a sign of advanced cancer. Radiation directed to the sites where the cancer is located and chemotherapy drugs injected by lumbar puncture directly into the CSF are the two main treatments available.
Prognosis, prevention, and outcomes: Leptomeningeal carcinoma is a sign of terminal cancer. If untreated, the average survival time is four to six weeks. When treated, the average survival time is three to seven months, depending on the type of primary cancer. Usually, the individual dies from either the primary cancer or complications of cancer treatment rather than directly from leptomeningeal carcinoma.
Bibliography
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