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Leptomeningeal metastasis (LMD) refers to the dissemination of cancer to the arachnoid mater, cerebrospinal fluid (CSF), and pia mater, which occurs in approximately 5% to 8% of all patients with cancer. The incidence of LMD may increase with better treatments and the overall longer survival of patients with cancer in general. The management of LMD requires the expertise of medical and neuro-oncologists, neurosurgeons, and radiation oncologists. LMD is typified by multifocal neurologic deficits and short survival in the 3- to 6-month range. The current standard of care includes external beam radiotherapy, and systemic and intrathecal (IT) chemotherapy. Future improvements in outcomes depend on: advances in the understanding of the molecular changes that allow for central nervous system seeding of cancer, the identification of subgroups of patients who can be predicted to develop LMD and in whom preventative measures can be instituted, and the development of effective drugs that penetrate, or can be directly administered into, the CSF.
Epidemiology
It is estimated that between 5% and 8% of patients with cancer will develop LMD.
Of patients with cancer who have neurologic symptoms and who undergo autopsy, as many as 19% can show evidence of leptomeningeal seeding by their cancer.
Based on recent data from the National Cancer Institute (NCI) Surveillance Epidemiology and End Results (SEER) Web site, the age-adjusted incidence for all cancers is 461.6 per 100,000 men and women per year.
Using 300 million as the population of the United States, this equates to approximately 1.4 million cancer cases, and as many as 110,000 LMD cases, per year in the United States.
The most common cancers that result in LMD include lung cancer, breast cancer, melanoma, acute lymphoblastic leukemia (ALL), and non-Hodgkin lymphoma (NHL), but virtually any cancer can metastasize to the leptomeninges. The incidence of LMD may increase in the future because of improved survival for cancers in general. The increased use of large-molecule systemic therapies that create a sanctuary site for cancer cells behind the blood-brain barrier and blood-CSF barrier (BCSFB) may also promote the development of LMD.
Pathophysiology
The seeding of cancer cells to the leptomeninges and CSF can be considered from an anatomic or from a molecular pathophysiology perspective. Anatomically, tumor cells must reach the leptomeninges to disseminate through the system. This dissemination occurs through either hematologic dissemination, via direct extension from a tumor mass adjacent to the meninges, or from a preexisting parenchymal central nervous system (CNS) metastasis
Intraoperative spread of tumor cells from a CNS metastasis is uncommon but does occur as shown by the way piecemeal tumor resection (vs en bloc resection or stereotactic radiation) increases CSF dissemination rates 2.4- to 5.8-fold.
Comparative risk of leptomeningeal dissemination of cancer after surgery or stereotactic radiosurgery for a single supratentorial solid tumor metastasis.
Primary CNS malignancies, such as medulloblastomas, pineal region tumors, and spinal cord tumors that reside near the CSF pathways, are particularly prone to CSF dissemination.
Once tumor cells reach the leptomeninges, they can disseminate throughout the CNS. Tumor cells can travel along the pia mater and invade the subpial parenchyma, penetrate nerves, and produce masses in the subarachnoid space. Cells can be carried in the CSF flow through the nervous system, resulting in multifocal CNS disease. The skull base and the sacral thecal sac are particularly prone to tumor cell build up because of their gravitationally dependent positions.
The molecular pathophysiology of LMD is not well understood. However, the principles that apply to metastatic disease in general
apply to LMD. To successfully metastasize, tumor cells must (1) possess unlimited growth potential and a high level of genomic instability; (2) be able to invade basement membranes and mobilize bone marrow constituents; (3) be able to remodel blood vessels, survive in the circulatory system and evade immune surveillance, and extravasate out of the vascular system; and (4) invade, proliferate, and establish a blood supply in the host organ.
These cellular activities require the hijacking of complex molecular machinery typically active during embryogenesis. Even though specific genetic mutations that produce LMD have not been identified, some molecular signals related to the disease have been found. Homing proteins, such as stromal derived factor-1 alpha
Biomarkers of disease: cerebrospinal fluid vascular endothelial growth factor (VEGF) and stromal cell derived factor (SDF)-1 levels in patients with neoplastic meningitis (NM) due to breast cancer, lung cancer and melanoma.
Biomarkers of disease: cerebrospinal fluid vascular endothelial growth factor (VEGF) and stromal cell derived factor (SDF)-1 levels in patients with neoplastic meningitis (NM) due to breast cancer, lung cancer and melanoma.
are present in increased levels in the CSF of patients with LMD. These proteins may be related to the biology and development of the disease, or simply epiphenomena.
Diagnosis
Clinical Findings
Symptoms and signs of LMD are related to the location of tumor deposits, or obstruction of CSF flow pathways, and are usually organized into 3 categories: cerebral, cranial nerve, and spinal.
Common cerebral symptoms and signs include headache, altered mental status, gait difficulty, nausea or vomiting, incoordination, syncope, and cerebellar signs. The most frequent cranial nerve–related symptoms are diplopia, vision loss, hearing changes, and facial weakness. Common spinal symptoms include lower motor neuron weakness, paresthesias, radicular pain, neck or back pain, and bladder or bowel dysfunction. Multifocal symptoms and findings are typical in patients with LMD.
Imaging
Because of its higher sensitivity, gadolinium contrast-enhanced magnetic resonance imaging (MRI) of the CNS has replaced computed tomography as the imaging modality of choice in patients suspected of having LMD.
Imaging of the entire neuraxis is necessary to properly quantify the extent of CNS disease and to allow for a coherent and organized treatment plan. Imaging findings on MRI that are suggestive of LMD include contrast enhancement of the leptomeninges, subependyma, cranial and spinal nerves, as well as communicating hydrocephalus.
Typical imaging findings of LMD are depicted in Fig. 1, Fig. 2, Fig. 3, Fig. 4. Neuroimaging is more likely to be abnormal in patients with LMD from solid tumors (72%–80%) versus those with LMD caused by hematologic malignancies (48%–62%).
Fig. 1Axial T1 contrast-enhanced MRI of the brain in a 44-year-old woman with metastatic melanoma and positive cytology for malignant cells. Image (arrow) shows subtle linear contrast enhancement along a sulcus in the right frontal lobe.
Fig. 2Axial T1-weighted contrast-enhanced MRI of the brain in a 62-year-old woman with breast cancer and positive cytology for malignant cells. Image (arrow) shows prominent enhancement along the cerebellar folia, typical of LMD. This patient had a pronounced response, lasting more than 5 months, to single-agent intrathecal methotrexate.
Fig. 3Sagittal T1 contrast-enhanced MRI of the lumbosacral spine in a 50-year-old woman with breast cancer and CSF cytology positive for malignant cells. Image (arrow) shows shaggy contrast enhancement along the nerve roots of the cauda equina, typical of extensive LMD.
Fig. 4(A) Sagittal contrast-enhanced MRI of the thoracic spine in a 64-year-old man with non–small cell cancer and malignant cells in the CSF. Image reveals an area of contrast enhancement on the surface of the midthoracic spinal cord. (B) Axial contrast-enhanced MRI of the thoracic spine through the area of enhancement on image (A) showing enhancement on the right dorsolateral surface of the spinal cord, and enhancement along the adjacent thoracic spinal nerve root.
Leptomeningeal enhancement is suggestive of LMD, but not diagnostic. Therefore, one must consider other conditions that can produce similar imaging features, such as the effects of intracranial hypotension after craniotomy or lumbar puncture, as well as infectious or inflammatory diseases.
Up to 61% of patients with LMD develop CSF flow blocks at various levels along the CSF pathway.
Therefore, once a decision is made to treat a patient who has LMD with intrathecal (IT) chemotherapy, CSF flow is assessed by injecting a radioactive tracer (usually pentaacetic acid labeled with indium 111). Focal radiation that opens areas of CSF flow obstruction improves survival.
111Indium-diethylenetriamine pentaacetic acid CSF flow studies predict distribution of intrathecally administered chemotherapy and outcome in patients with leptomeningeal metastases.
Cytologic examination of the CSF identifying malignant cells is the sine qua non of the diagnosis of LMD. However, the sensitivity of a single CSF cytologic examination can be as low as 45%,
Four simple measures can increase the likelihood of finding malignant cells from a CSF sample: (1) obtain at least 10.5 mL of CSF for analysis, (2) immediately process the sample, (3) obtain CSF from a site adjacent to the affected CNS region, and (4) repeat the CSF sampling and analysis.
Discordance between imaging and CSF findings is common. In patients with LMD who have solid tumors, CSF is negative in 17% to 23% in the face of positive MRI findings. Conversely, in patients with LMD who have liquid tumors, MRI is unrevealing in 38% to 52% of patients whose CSF contains malignant cells.
Because of their lack of specificity, other standard CSF analyses performed at the time of lumbar puncture can only be used to direct attention toward additional testing, rather than provide a basis for treatment. Traditional CSF analyses include CSF opening pressure, increased (>20 cm water) in 50% of patients with LMD; CSF white blood cell count, increased (>5 per mm3) in 64% of patients with LMD; CSF protein concentration, increased (>50 mg/dL) in 59% of patients with LMD; and CSF glucose concentration, low (<40 mg/dL) in 31% of patients with LMD.
Potential usefulness has been noted for CSF levels of β glucuronidase, lactate dehydrogenase, β-2-microglobulin, carcinoembryonic antigen, and β-human chorionic gonadotrophin. However, none of these molecules have become widely used, primarily because of their lack of specificity. If identified, these markers can be used to track disease progress, but the serum levels of the molecules must also be followed to ensure that there is true CSF production rather than transfer across the BCSFB.
Recent studies have identified increased levels of molecules in the CSF of patients with LMD related to cellular homing and migration, and angiogenesis.
Biomarkers of disease: cerebrospinal fluid vascular endothelial growth factor (VEGF) and stromal cell derived factor (SDF)-1 levels in patients with neoplastic meningitis (NM) due to breast cancer, lung cancer and melanoma.
These may prove useful in tracking or targeting the disease, or in better understanding its biology.
In hematological malignancies, flow cytometry analysis of the CSF improves the sensitivity compared with standard CSF morphologic cytologic analysis, and is the preferred testing method when LMD is a concern.
High incidence of occult leptomeningeal disease detected by flow cytometry in newly diagnosed aggressive B-cell lymphomas at risk for central nervous system involvement: the role of flow cytometry versus cytology.
Aggressive treatment of patients with LMD is controversial; this is because of the low efficacy of most treatments, the overall poor prognosis, and the risks of treatment-related toxicities. Many clinicians advise against aggressive treatment for patients with LMD. Even though neurologic deficits rarely improve, one argument in favor of treatment is that early intervention may improve quality of life and prevent neurologic death.
Treatment of LMD is considered palliative, because even aggressive treatment directed at the leptomeninges may only increase survival by 1 to 3 months.
Without intervention, median survival is typically 4 to 6 weeks, after which death is often caused by progressive neurologic decline.
Therapy for LMD can provide control of the meningeal disease. However, even with treatment, one-quarter of patients with LMD die as a direct consequence of the LMD, and up to 60% die with simultaneous progression of the LMD and the systemic cancer.
Treatment of LMD should target the entire neuraxis because tumor cells disseminate throughout the CSF pathway. For a comprehensive approach, both bulky disease and malignant cells floating in the CSF, as well as the patient’s systemic disease, are treated. This most comprehensive approach requires focal (radiotherapy to bulky meningeal disease), local (IT chemotherapy for the disease present in the CSF), and systemic (systemic chemotherapy for cancer outside the nervous system) treatments.
Guidelines published by the National Comprehensive Cancer Network (2006)
suggest stratifying patients as either poor or good risks for survival to aid in determining how aggressive the treatment should be. These guidelines define poor-risk patients as those with (1) a low Karnofsky performance scale (KPS) score; (2) multiple, serious, fixed neurologic deficits; and (3) extensive systemic disease with few treatment options. These patients may be best served by supportive care and radiotherapy to symptomatic sites of disease. Patients who are a good risk and who may warrant more aggressive treatment are those with (1) a high KPS score, (2) no fixed neurologic deficits, (3) limited systemic disease, and (4) effective systemic treatment options.
Because of physical or cognitive impairment, patients with LMD may require more assistance than is readily available. For practicality and safety, modifications of the home and special means of transportation may be necessary. Counseling to address the psychological burden of LMD on patients and their caregivers is often warranted.
Radiotherapy
External beam radiotherapy is often used in patients with LMD.
Involved field radiotherapy can be delivered to the meninges if bulky disease is present and causing symptoms (often seen with involvement of cranial nerves) or when CSF flow obstruction occurs. Thirty Gray given in 10 fractions is a typical radiation dosing scheme. Because of the higher likelihood of response, patients with breast cancer, leukemia, and lymphoma are considered best for this therapy. Even though the entire CSF system might be considered a target for radiotherapy, craniospinal radiotherapy is rarely administered because of toxicity concerns.
In adults with ALL (aALL), systemic chemotherapy (SC) agents possessing high levels of CNS penetration, along with IT chemotherapy, are now standard in the prevention of LMD.
The value of high-dose systemic chemotherapy and intrathecal therapy for central nervous system prophylaxis in different risk groups of adult acute lymphoblastic leukemia.
The value of high-dose systemic chemotherapy and intrathecal therapy for central nervous system prophylaxis in different risk groups of adult acute lymphoblastic leukemia.
The studies supporting the CNS prophylactic approach in adults were undertaken to try to emulate the outcomes seen in childhood ALL (cALL). In cALL, before the incorporation of CNS prophylaxis, the risk of the development of CNS leukemia at 4 years was 75%.
Evidence to support the use of SC (or hormonal therapy) in the treatment or prophylaxis of solid tumor LMD is less strong. However, there are reports of responses and improved survival in patients with LMD treated with SC, often without IT chemotherapy.
Meningeal carcinomatosis in patients with breast carcinoma. Clinical features, prognostic factors, and results of a high-dose intrathecal methotrexate regimen.
Despite reports of usefulness, the use of SC in LMD is questioned because therapeutic CSF concentrations of most SCs are usually not considered to be achievable. Table 1 lists commonly used SCs that achieve greater than 0.05 CSF/plasma ratio (a ratio <0.05 signifies nonspecific leakage of drug across the BCSFB). Reasonable approaches to treating LMD include the use of SCs with high levels of CSF penetration either with or without IT chemotherapy. However, there is a risk for increased neurotoxicity when combining such agents.
Neurologic complications associated with intrathecal liposomal cytarabine given prophylactically in combination with high-dose methotrexate and cytarabine to patients with acute lymphocytic leukemia.
Phase I and pharmacokinetic evaluation of thiotepa in the cerebrospinal fluid and plasma of pediatric patients: evidence for dose-dependent plasma clearance of thiotepa.
The theory behind using IT chemotherapy is to treat (1) subclinical leptomeningeal deposits and (2) any viable tumor cells floating in the CSF to prevent further leptomeningeal seeding, thereby preserving neurologic functioning and improving survival. As noted earlier, not all clinicians advise the use of IT chemotherapy because of limited randomized data showing benefit, and concerns about toxicity.
Route of administration of intrathecal chemotherapy
To avoid frequent lumbar punctures and injury, and for possible improved efficacy of treatment, most patients with LMD have a ventricular reservoir placed for drug delivery. Delivery of chemotherapeutic drugs by lumbar puncture can result in drug placement outside the thecal sac and accompanying tissue damage. More variability of ventricular drug concentrations is seen after intralumbar drug administration. For drugs with a short half-life, intraventricular administration results in better outcomes, probably because of the more even distribution of the drug throughout the thecal sac.
Ventricular reservoirs are usually well tolerated, but complications such as misplacement, catheter tip occlusion, and infection can occur in as many as 5% of patients.
The most commonly used IT chemotherapies for LMD from all causes include the antimetabolite, methotrexate (MTX); the pyrimidine analogue, cytarabine (Ara-C) and its longer-acting liposomal version; and the alkylator, thiotepa (triethylenethiophosphoramide). Typical schedules of administration of IT chemotherapies include a high-dose induction phase (dose based on specific drug, usually twice weekly × 4–6 weeks), followed by a less intensive consolidation phase (usually once-weekly dosing) and an even less intensive maintenance phase.
Few randomized data exist comparing the efficacy of these drugs. In the randomized studies that do exist, nonsignificant differences in survival have been shown when comparing IT chemotherapies with each other or in various combinations.
A randomized controlled trial comparing intrathecal sustained-release cytarabine (DepoCyt) to intrathecal methotrexate in patients with neoplastic meningitis from solid tumors.
However, in lymphomatous meningitis, liposomal Ara-C results in a higher degree of tumor cell clearance from the CSF and a longer median time to neurologic progression and survival duration compared with the standard formulation of Ara-C.
IT Ara‑C can cause neuropathy, cerebellar, or spinal cord injury. IT MTX can cause acute arachnoiditis, nausea, vomiting, and mental status change and may be associated with seizures.
IT MTX can also cause mucositis and myelosuppression if not followed by systemic administration of folinic acid. IT thiotepa toxicity is similar to that of IT MTX; however, it may cause more hematologic toxicity.
Randomized prospective comparison of intraventricular methotrexate and thiotepa in patients with previously untreated neoplastic meningitis. Eastern Cooperative Oncology Group.
Radiotherapy can worsen myelosuppression in heavily pretreated patients who have cancer, and may raise the chance of neurotoxicity from IT chemotherapy.
Necrotizing leukoencephalopathy, especially when IT MTX is administered after radiotherapy, is a severe complication to be avoided. A less fulminate leukoencephalopathy, manifested by dementia, seizure, progressive tetraparesis, and change in white matter, may be more likely to occur in patients receiving IT chemotherapy versus those receiving SC.
CSF flow obstruction caused by arachnoid granulation blockade by cellular debris can cause symptoms of cerebral hypoperfusion. These symptoms may be caused by a relative increase in intracranial pressure compared with systemic blood pressure and can be misdiagnosed as syncope or seizure activity. Resolution of symptoms with CSF drainage can help alleviate the patient’s symptoms. Long-term management of this problem can be accomplished with CSF diversion, or through administration of acetazolamide.
Prognosis
Without LMD-directed therapy, patients have survivals in the 3- to 6-week range. Death is often caused by progressive neurologic dysfunction.
Patients with hematologic malignancies and LMD have better survivals (4.7 months) compared with those with LMD from solid tumors (2.3 months) (P = .0006).
Among solid tumors, patients who have breast cancer with LMD who receive treatment tend to have the best outcomes, with median survivals of 4.5 months and up to 25% 1-year survival.
Experimental therapies for LMD include both systemic and IT agents. None have yet shown enough promise, or are far enough along in development, to have supplanted the older interventions.
Systemic Therapies
Bevacizumab
Bevacizumab is a systemically administered monoclonal antibody targeting the proangiogenic protein, VEGF-A. It is approved by the US Food and Drug Administration for use in several malignant diseases. Recent reports found increased VEGF-A levels in the CSF of patients with LMD with solid tumors
Biomarkers of disease: cerebrospinal fluid vascular endothelial growth factor (VEGF) and stromal cell derived factor (SDF)-1 levels in patients with neoplastic meningitis (NM) due to breast cancer, lung cancer and melanoma.
Systemically administered bevacizumab is currently being tested in patients with LMD with solid tumors.
Gefitinib
Gefitinib is a small-molecule tyrosine kinase inhibitor with activity against lung cancers possessing activating mutations of the epidermal growth factor receptor (EGFR). Case reports show responses to EGFR inhibitors in patients with LMD caused by non–small cell lung cancer (NSCLC).
Response and resistance in a non-small-cell lung cancer patient with an epidermal growth factor receptor mutation and leptomeningeal metastases treated with high-dose gefitinib.
High-dose gefitinib (5 times standard doses) was recently prospectively evaluated in patients with LMD caused by NSCLC whose tumors possess activating EGFR mutations. Early reports of the clinical outcomes are promising; final results are pending (D. Jackman, MD, Boston, MA, personal communication, June 2009).
Pemetrexed
Pemetrexed (PMX) is an antimetabolite, similar to MTX, and is approved for mesothelioma and NSCLC. PMX is active in some MTX-resistant malignancies. The CSF pharmacokinetics of systemically administered PMX are currently being evaluated in patients with LMD. The drug is unique in that it acts through several enzyme systems involved in folate metabolism and gains intracellular access through at least 4 mechanisms, possibly increasing its activity compared with MTX. There are early CSF responses in patients with LMD with breast cancer (J. Raizer, MD, Chicago, IL, personal communication, June 2009).
Intrathecal Therapies
Cytotoxic therapies
The search for more effective, less toxic IT cytotoxic therapies is ongoing. Recently tested IT cytotoxic chemotherapies with some degree of efficacy and modest toxicity are presented in Table 2. Of these, the topoisomerase inhibitors seem particularly promising for further study (possibly in combination with other IT agents or systemic treatments), in light of their mild toxicity profile, and reasonable efficacy.
To try to further enhance its activity by prolonging tumor cell exposure to drug, a concentration-times-time study of IT topotecan is ongoing within the Pediatric Brain Tumor Consortium.
Table 2Newer intrathecal cytotoxic chemotherapies
Data from Groves MD. Leptomeningeal metastases: still a challenge. Am Soc Clin Oncol Ed Book 2008:80–87.
Phase I clinical trial of mafosfamide in infants and children aged 3 years or younger with newly diagnosed embryonal tumors: a Pediatric Brain Tumor Consortium study (PBTC-001).
IT delivery of the β emitter, 131I, has shown some activity in LMD. IT administration of the nonbound formulation of 131I, sodium iodide, resulted in almost no toxicity and achieved CSF tumor cell clearance in 29% of patients.
Phase 1 data suggest possible efficacy in childhood primitive neuroectodermal tumors and neuroblastoma.
Monoclonal Antibodies
Rituximab
Rituximab is a humanized monoclonal antibody targeting the CD-20 antigen, which is expressed on most B-cell lymphomas and leukemias. In 1997, Rituximab was approved for intravenous use in B-cell lymphoma. Because of its large size (146 kDa), the CSF/serum ratio of this molecule is only 0.001 after intravenous administration.
A recently reported phase 1 study of IT rituximab in adults identified 25 mg twice weekly (9 doses total) as the maximum tolerated dose. The estimated half-life of the drug was 34.9 hours. Cytologic responses (including complete responses) and improvements in intraocular and intraparenchymal lymphoma were seen in most patients. Toxicities were mild and included chills and hypertension.
A smaller dose (10 mg weekly) of IT rituximab has been tested in children with B-cell ALL. In 5 of the 7 subjects, a complete response was achieved. The 2 that relapsed did so outside the CNS.
Further refinement of the use of this agent in applicable diseases warrants study.
Trastuzumab
Thirty percent of primary breast cancers overexpress the EGFR 2 protein (HER2), which is targeted by the humanized monoclonal antibody, trastuzumab. Trastuzumab destroys tumor cells through antibody-dependent mechanisms; it does not reach the CSF in significant concentrations, even after CNS-directed radiotherapy for LMD.
Ratio of trastuzumab levels in serum and cerebrospinal fluid is altered in HER2-positive breast cancer patients with brain metastases and impairment of blood-brain barrier.
Based on these findings, results from a pilot study using IT trastuzumab in patients with LMD caused by breast cancer, medulloblastoma, or glioblastoma were recently presented.
Intra-CSF trastuzumab in patients with neoplastic meningitis from breast cancer or primary brain tumors[abstract 2066]. ASCO Annual Meeting Proceedings.
IT trastuzumab was administered at 20 to 60 mg per dose, either weekly or every other week for 4 treatments, then continued every other week until progression. Responses were seen in 7 of 11 patients with glioblastoma, 2 of 4 patients with breast cancer and in the single patient with medulloblastoma. The HER2 receptor status was predictive of response. No adverse events were reported. Further study of IT trastuzumab, either alone or in combination with other approaches, is warranted.
Combination Therapies
Combination of IT and systemic therapies may improve outcomes in LMD.
Meningeal carcinomatosis in patients with breast carcinoma. Clinical features, prognostic factors, and results of a high-dose intrathecal methotrexate regimen.
Ongoing studies that combine IT and systemic therapies include a study evaluating IT liposomal Ara-C plus systemic bevacizumab in patients with LMD with primary brain tumors, and a study of oral capecitabine plus liposomal Ara-C in patients who have breast cancer with LMD (Ricardo Soffietti, MD, Turin, Italy, personal communication, May, 2010).
Successful treatment without cranial radiotherapy of children receiving intensified chemotherapy for acute lymphoblastic leukaemia: results of the risk-stratified randomized central nervous system treatment trial MRC UKALL XI (ISRC TN 16757172).
inspire the hope of similar advances in other forms of LMD. Similar approaches will become feasible when biomarkers with a high enough positive predictive value can be identified. Useful biomarkers could include (1) molecular changes within the primary or metastatic tumors that predict CNS or CSF metastases, (2) changes within the host genome that predict CNS and CSF metastasis development, (3) plasma or CSF biomarkers that predict LMD before its clinical development. Preliminary data suggest that CSF VEGF may be such a marker,
Biomarkers of disease: cerebrospinal fluid vascular endothelial growth factor (VEGF) and stromal cell derived factor (SDF)-1 levels in patients with neoplastic meningitis (NM) due to breast cancer, lung cancer and melanoma.
but further validation is needed. In conjunction with an effective biomarker, an intervention with a high therapeutic index will be needed.
Clinical scenarios (surrogates for the underlying disease biology) can identify patients at higher risk of LMD, and can possibly serve as signals for treatment. Recent work has shown that patients with brain metastases (BM) who undergo piecemeal resection of their tumors (compared with en bloc resection or stereotactic radiosurgery [SRS]) have an increased risk of developing LMD.
Comparative risk of leptomeningeal dissemination of cancer after surgery or stereotactic radiosurgery for a single supratentorial solid tumor metastasis.
Risk of LMD in patients having piecemeal resection may be as much as 2.45 to 5.8 times higher than in those only receiving SRS. Patients with BM who undergo piecemeal resection of their tumors may be a good population in which to test prophylactic interventions against LMD.
Summary
LMD is a lethal complication caused by a variety of cancers, typically developing late in the disease course. It is associated with major neurologic disabilities and short survival. The incidence of LMD may increase because of longer survival of patients who have cancer, and because of the use of newer large-molecule therapies with poor CNS penetration. The molecular changes responsible for the development of LMD are still mostly unknown.
To achieve improved outcomes for patients who have LMD, new treatments need to reach the meninges and CSF and interact with relevant molecular targets. Some of the agents currently in testing may contribute to this goal. To allow for better outcomes through earlier treatment, and ultimately prevention of LMD, stepwise advances in diagnosis are needed. These steps include the appreciation of clinical scenarios predisposing to the development of LMD, the validation of circulating plasma and CSF cellular and soluble biomarkers, and, ultimately, biomarkers derived from the genome of the tumor and host. At each step, and with agents with higher therapeutic indices, it should be possible to develop interventions based on likelihood ratios to allow for gradual improvements in outcomes for patients suffering from this devastating disease.
References
DeAngelis L.M.
Posner J.B.
Neurologic complications of cancer. (Contemporary neurology series).
Comparative risk of leptomeningeal dissemination of cancer after surgery or stereotactic radiosurgery for a single supratentorial solid tumor metastasis.
Biomarkers of disease: cerebrospinal fluid vascular endothelial growth factor (VEGF) and stromal cell derived factor (SDF)-1 levels in patients with neoplastic meningitis (NM) due to breast cancer, lung cancer and melanoma.
111Indium-diethylenetriamine pentaacetic acid CSF flow studies predict distribution of intrathecally administered chemotherapy and outcome in patients with leptomeningeal metastases.
High incidence of occult leptomeningeal disease detected by flow cytometry in newly diagnosed aggressive B-cell lymphomas at risk for central nervous system involvement: the role of flow cytometry versus cytology.
The value of high-dose systemic chemotherapy and intrathecal therapy for central nervous system prophylaxis in different risk groups of adult acute lymphoblastic leukemia.
Meningeal carcinomatosis in patients with breast carcinoma. Clinical features, prognostic factors, and results of a high-dose intrathecal methotrexate regimen.
Neurologic complications associated with intrathecal liposomal cytarabine given prophylactically in combination with high-dose methotrexate and cytarabine to patients with acute lymphocytic leukemia.
A randomized controlled trial comparing intrathecal sustained-release cytarabine (DepoCyt) to intrathecal methotrexate in patients with neoplastic meningitis from solid tumors.
Randomized prospective comparison of intraventricular methotrexate and thiotepa in patients with previously untreated neoplastic meningitis. Eastern Cooperative Oncology Group.
Response and resistance in a non-small-cell lung cancer patient with an epidermal growth factor receptor mutation and leptomeningeal metastases treated with high-dose gefitinib.
Ratio of trastuzumab levels in serum and cerebrospinal fluid is altered in HER2-positive breast cancer patients with brain metastases and impairment of blood-brain barrier.
Intra-CSF trastuzumab in patients with neoplastic meningitis from breast cancer or primary brain tumors[abstract 2066]. ASCO Annual Meeting Proceedings.
Successful treatment without cranial radiotherapy of children receiving intensified chemotherapy for acute lymphoblastic leukaemia: results of the risk-stratified randomized central nervous system treatment trial MRC UKALL XI (ISRC TN 16757172).
Phase I and pharmacokinetic evaluation of thiotepa in the cerebrospinal fluid and plasma of pediatric patients: evidence for dose-dependent plasma clearance of thiotepa.
Phase I clinical trial of mafosfamide in infants and children aged 3 years or younger with newly diagnosed embryonal tumors: a Pediatric Brain Tumor Consortium study (PBTC-001).
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