Leptomeningeal neoplasia: epidemiology, clinical presentation, CSF analysis and diagnostic imaging

Leptomeningeal metastases from solid tumors: A Society for Neuro-Oncology and American Society of Clinical Oncology consensus review on clinical management and future directions

Leptomeningeal metastases (LM) are increasingly becoming recognized as a treatable, yet generally incurable, complication of advanced cancer. As modern cancer therapeutics have prolonged the lives of patients with metastatic cancer, specifically in patients with parenchymal brain metastases, treatment options, and clinical research protocols for patients with LM from solid tumors have similarly evolved to improve survival within specific populations. Recent expansions in clinical investigation, early diagnosis, and drug development have given rise to new unanswered questions. These include leptomeningeal metastasis biology and preferred animal modeling, epidemiology in the modern cancer population, ensuring validation and accessibility of newer leptomeningeal metastasis diagnostics, best clinical practices with multimodality treatment options, clinical trial design and standardization of response assessments, and avenues worthy of further research. An international group of multi-disciplinary experts in the research and management of LM, supported by the Society for Neuro-Oncology and American Society of Clinical Oncology, were assembled to reach a consensus opinion on these pressing topics and provide a roadmap for future directions. Our hope is that these recommendations will accelerate collaboration and progress in the field of LM and serve as a platform for further discussion and patient advocacy.

Mass spectrometry-based proteomics of cerebrospinal fluid in pediatric central nervous system malignancies: a systematic review with meta-analysis of individual patient data

BACKGROUND

The cerebrospinal fluid (CSF) proteome could offer important insights into central nervous system (CNS) malignancies. To advance proteomic research in pediatric CNS cancer, the current study aims to (1) evaluate past mass spectrometry-based workflows and (2) synthesize previous CSF proteomic data, focusing on both qualitative summaries and quantitative re-analysis. MAIN: In our analysis of 11 studies investigating the CSF proteome in pediatric patients with acute lymphoblastic leukemia (ALL) or primary brain tumors, we observed significant methodological variability. This variability negatively affects comparative analysis of the included studies, as per GRADE criteria for quality of evidence. The qualitative summaries covered 161 patients and 134 non-tumor controls, while the application of validation cohort varied among the studies. The quantitative re-analysis comprised 15 B-ALL vs 6 "healthy" controls and 15 medulloblastoma patients vs 22 non-tumor controls. Certain CSF proteins were identified as potential indicators of specific malignancies or stages of neurotoxicity during chemotherapy, yet definitive conclusions were impeded by inconsistent data. There were no proteins with statistically significant differences when comparing cases versus controls that were corroborated across studies where quantitative reanalysis was feasible. From a gene ontology enrichment, we observed that age disparities between unmatched case and controls may mislead to protein correlations more indicative of age-related CNS developmental stages rather than neuro-oncological disease. Despite efforts to batch correct (HarmonizR) and impute missing values, merging of dataset proved unfeasible and thereby limited meaningful data integration across different studies.

CONCLUSION

Infrequent publications on rare pediatric cancer entities, which often involve small sample sizes, are inherently prone to result in heterogeneous studies-particularly when conducted within a rapidly evolving field like proteomics. As a result, obtaining clear evidence, such as CSF proteome biomarkers for CNS dissemination or early-stage neurotoxicity, is currently impractical. Our general recommendations comprise the need for standardized methodologies, collaborative efforts, and improved data sharing in pediatric CNS malignancy research. We specifically emphasize the possible importance of considering natural age-related variations in CSF due to different CNS development stages when matching cases and controls in future studies.

Cerebrospinal fluid: A unique source of circulating tumor DNA with broad clinical applications

Malignancies involving the central nervous system present unique challenges for diagnosis and monitoring due to the difficulties and risks of direct biopsies and the low specificity and/or sensitivity of other techniques for assessment. In recent years, liquid biopsy of the cerebrospinal fluid (CSF) has emerged as a convenient alternative that combines minimal invasiveness with the ability to detect disease-defining or therapeutically actionable genetic alterations from circulating tumor DNA (ctDNA). Since CSF can be obtained by lumbar puncture, or an established ventricular access device at multiple time points, ctDNA analysis enables initial molecular characterization and longitudinal monitoring throughout a patient's disease course, promoting optimization of treatment regimens. This review outlines some of the key aspects of ctDNA from CSF as a highly suitable approach for clinical assessment, the benefits and drawbacks, testing methods, as well as potential future advancements in this field. We anticipate wider adoption of this practice as technologies and pipelines improve and envisage significant improvements for cancer care.

Targeting Leukemia-Initiating Cells and Leukemic Niches: The Next Therapy Station for T-Cell Acute Lymphoblastic Leukemia?

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive subtype of hematological malignancy characterized by its high heterogeneity and potentially life-threatening clinical features. Despite the advances in risk stratification and therapeutic management of T-ALL, patients often suffer from treatment failure and chemotherapy-induced toxicity, calling for greater efforts to improve therapeutic efficacy and safety in the treatment of T-ALL. During the past decades, increasing evidence has shown the indispensable effects of leukemia-initiating cells (LICs) and leukemic niches on T-ALL initiation and progression. These milestones greatly facilitate precision medicine by interfering with the pathways that are associated with LICs and leukemic niches or by targeting themselves directly. Most of these novel agents, either alone or in combination with conventional chemotherapy, have shown promising preclinical results, facilitating them to be further evaluated under clinical trials. In this review, we summarize the latest discoveries in LICs and leukemic niches in terms of T-ALL, with a particular highlight on the current precision medicine. The challenges and future prospects are also discussed.

A retrospective analysis of first-line PD-1 monoclonal antibodies treatment in patients with leptomeningeal metastasis from solid tumors

Introduction

Patients whose solid tumors (ST) show leptomeningeal metastasis (LM) have very poor prognosis and short overall survival. The aim of this study was to evaluate the efficacy of first-line programed death-1(PD-1) monoclonal antibody (mAb) treatment in these patients.

Methods

We retrospectively evaluated patients diagnosed with LM from ST who were treated with first-line PD-1 mAb at our hospital between April 1 and November 30, 2019. We analyzed their clinicopathological characteristics and response to the treatment.

Results

We collected and analyzed data from 6 patients with different primary ST. 5 patients received PD-1 mAb combined with chemotherapy and/or anti-angiogenic drugs, while one received only PD-1 mAb. The median (range) number of treatment cycles was 5.5 (1-21). PD-1 mAb treatment did not cause neurotoxicity. The time period of first assessment varied from 21 to 65 days after treatment. Among 5 patients who got obvious symptoms relief, 4 patients persisted for > 3 months and even showed a reduction in the number of tumor cells in cerebrosprinal fluid. Ventriculoperitoneal (VP) shunt was used to treat hydrocephalus observed beneficial in 3 patients: 2 before and 1 after PD-1 mAb treatment. The median (range) follow-up time was 214 (57-460) days. 4 patients died. The overall survival ranged from 57 days to at least 460 days. 1 of the two alive patients continued to show no worsening of symptoms after 457 days.

Conclusions

Patients with LM from ST can benefit from first-line PD-1 mAb combined treatment without additional neurotoxicity. Further research is required to validate the safety and efficacy.

Neoplastic meningitis in solid tumours: updated review of diagnosis, prognosis, therapeutic management, and future directions

Neoplastic meningitis (NM) is a relatively frequent metastatic complication of cancer associated with high levels of neurological morbidity and generally poor prognosis. It appears in 5%-15% of patients with solid tumours, the most frequent being breast and lung cancer and melanoma. Symptoms are caused by involvement of the cerebral hemispheres, cranial nerves, spinal cord, and nerve roots, and are often multifocal or present with signs and symptoms of intracranial hypertension. The main diagnostic tools are the neurological examination, brain and spinal cord contrast-enhanced magnetic resonance imaging, and cerebrospinal fluid analysis including cytology, although studies have recently been conducted into the detection of tumour cells and DNA in the cerebrospinal fluid, which increases diagnostic sensitivity. With the currently available therapies, treatment aims not to cure the disease, but to delay and ameliorate the symptoms and to preserve quality of life. Treatment of NM involves a multimodal approach that may include radiotherapy, intrathecal and/or systemic chemotherapy, and surgery. Treatment should be individualised, and is based mainly on clinical practice guidelines and expert opinion. Promising clinical trials are currently being conducted to evaluate drugs with molecular and immunotherapeutic targets. This article is an updated review of NM epidemiology, clinical presentation, diagnosis, prognosis, management, and treatment; it is aimed at general neurologists and particularly at neurologists practicing in hospital settings with oncological patients.

Neoplastic meningitis in solid tumours: Updated review of diagnosis, prognosis, therapeutic management, and future directions

Neoplastic meningitis (NM) is a relatively frequent metastatic complication of cancer associated with high levels of neurological morbidity and generally poor prognosis. It appears in 5%-15% of patients with solid tumours, the most frequent being breast and lung cancer and melanoma. Symptoms are caused by involvement of the cerebral hemispheres, cranial nerves, spinal cord, and nerve roots, and are often multifocal or present with signs and symptoms of intracranial hypertension. The main diagnostic tools are the neurological examination, brain and spinal cord contrast-enhanced magnetic resonance imaging, and cerebrospinal fluid analysis including cytology, although studies have recently been conducted into the detection of tumour cells and DNA in the cerebrospinal fluid, which increases diagnostic sensitivity. With the currently available therapies, treatment aims not to cure the disease, but to delay and ameliorate the symptoms and to preserve quality of life. Treatment of NM involves a multimodal approach that may include radiotherapy, intrathecal and/or systemic chemotherapy, and surgery. Treatment should be individualised, and is based mainly on clinical practice guidelines and expert opinion. Promising clinical trials are currently being conducted to evaluate drugs with molecular and immunotherapeutic targets. This article is an updated review of NM epidemiology, clinical presentation, diagnosis, prognosis, management, and treatment; it is aimed at general neurologists and particularly at neurologists practicing in hospital settings with oncological patients.

Management of leptomeningeal metastasis in breast cancer

Leptomeningeal metastasis (LM), which occurs when malignant cells spread to the central nervous system, is becoming an increasingly common complication in patients with breast cancer. Diagnosis and treatment of LM is challenging. Moreover, prognosis of patients with LM is poor, with a median survival of 6 months after diagnosis. This review highlights the strengths and limitations of currently available diagnostic tools and therapies for LM. The current treatments for LM, including radiotherapy, systemic therapy, and intrathecal treatment, aim to maintain the quality of life of patients by correcting neurological deficits and arresting neurological degeneration. However, there is no standardized therapy for LM because of a lack of randomized trials on this condition.

Management of neuro-oncologic emergencies

Patients with brain tumors and systemic malignancies are subject to diverse neurologic complications that require urgent evaluation and treatment. These neurologic conditions are commonly due to the tumor's direct effects on the nervous system, such as cerebral edema, increased intracranial pressure, seizures, spinal cord compression, and leptomeningeal metastases. In addition, neurologic complications can develop as a result of thrombocytopenia, coagulopathy, hyperviscosity syndromes, infection, immune-related disorders, and adverse effects of treatment. Patients may present with typical disease syndromes. However, it is not uncommon for patients to have more subtle, nonlocalizing manifestations, such as alteration of mental status, that could be attributed to other systemic, nonneurologic complications. Furthermore, neurologic complications are at times the initial manifestations of an undiagnosed malignancy. Therefore a high index of suspicion is essential for rapid assessment and management. Timely intervention may prolong survival and improve quality of life. In this chapter, we will discuss the common neuro-oncologic emergencies, including epidemiology, pathophysiology, clinical presentation, diagnosis, and treatment.

Patient outcomes of whole brain radiotherapy for brain metastases versus leptomeningeal metastases: A retrospective study

AIM

Important factors typically associated with prognosis in brain metastases include Karnofsky performance status (KPS), extracranial or cerebellar localization and combination chemotherapy. However, few studies investigated the prognostic role of leptomeningeal metastases (LM) following whole brain radiotherapy (WBRT). On the basis of our experience suggesting better survival of asymptomatic patients with LM than those with brain metastases, we herein evaluated LM as a prognostic factor after WBRT.

METHODS

Medical records of 206 patients (median age, 65 years) who received WBRT in 2007-2015 were retrospectively reviewed. The two most common cancers were of lung, breast origin in 78.5%, 10%, patients, respectively. Patients received parallel-opposed WBRT, with a dose of 20-40 Gy. Additional doses of 9-12 Gy were used in patients who were operated on or had single metastases. Overall survival (OS) was determined, and clinical parameters including age, KPS, symptoms, radiation dose, dose per fraction, type of metastasis, extracranial metastases, primary status and surgery plus WBRT were assessed as prognostic factors.

RESULTS

The median survival was 6 months (range, 1-100), and 1- and 2-year survival rates were 28% and 17%, respectively. In univariate analysis, improved survival was associated with KPS of ≥70, absence of symptoms, radiation dose of ≥37.5 Gy, favorable primary lesion, LM, and surgery plus WBRT. Multivariate analysis revealed that these factors with the exception of radiation dose was significant prognostic factors for OS.

CONCLUSION

We found that LM were independent prognostic factors for good clinical outcomes.

The utility of repeated cytologic evaluation of cerebrospinal fluid in individuals with metastatic breast cancer

INTRODUCTION

Metastasis of breast cancer to the central nervous system, either in the brain parenchyma or leptomeninges (LMC), is a late feature of the disease . Detection of malignant cells in the cerebrospinal fluid (CSF) is the diagnostic standard for LMC. Repeated CSF examinations are often performed following an initial diagnosis positive for malignancy. This study evaluates the significance of repeated CSF evaluation in women with metastatic breast cancer to the central nervous system.

MATERIALS AND METHODS

Cases of adenocarcinoma of breast diagnosed by CSF cytology from 1990 through 2012 documenting: age, radiologic findings, treatment modality, and the number of repeated CSF cytology specimens and their respective interpretations.

RESULTS

Fifty-one patients were identified; 28 patients (54.9%) had a single initial positive CSF performed and 23 (45.1%) had multiple CSF cytology samples (range = 2-25, mean = 5.5). Despite interval "negative" and "atypical cells" results on CSF cytology specimens, all 23 patients with multiple samples had at least one follow-up positive CSF cytology sample.

CONCLUSION

The prognosis of the patients with an initial CSF diagnosis of adenocarcinoma was poor, regardless of the respective interpretations on the repeated CSF specimens, even in the presence of interval negative CSF.

Safety of intra-cerebrospinal fluid chemotherapy in onco-haematological patients: a retrospective analysis of 627 interventions

Intra-cerebrospinal fluid chemotherapy (ICC) is used widely to treat or prevent neoplastic meningitis (NM), although its safety has not been thoroughly assessed. We aimed to analyse the incidence, severity and cause of the adverse reactions provoked by ICC in a cohort of onco-haematological patients. We retrospectively reviewed all the adverse reactions related to ICC procedures performed by the same researcher over a 5-year period. We classified them according to their severity and cause, and examined their association with certain characteristics of the patients and interventions. A total of 627 procedures were performed on 124 patients, in which 59 adverse reactions were documented (9.4 %). Thirty-two (54 %) of these were considered severe and 30 (51 %) were due to the drug itself. NM was associated with a higher incidence of adverse reactions (p = 0.002) and severe adverse reactions (p < 0.001). Adverse reactions were more common (p = 0.028) and more often severe (p = 0.008) when an Ommaya reservoir was used, as opposed to the lumbar puncture procedure. The use of liposomal cytarabine was also associated with a higher incidence of adverse reactions (p < 0.001) and serious adverse reactions (p < 0.001) than immediate-release drugs. Liposomal cytarabine provoked more adverse reactions attributable to the drug when administered by lumbar puncture (p = 0.192), whereas the remaining drugs had higher risk when administered via Ommaya reservoir (p = 0.015). ICC seems a relatively safe procedure. Adverse reactions appear to be more frequent when NM is already present. Lumbar puncture seems to be safer than the Ommaya reservoir, except when liposomal cytarabine is administered.

Flow cytometric analysis of cerebrospinal fluid has low diagnostic yield in samples without atypical morphology or prior history of hematologic malignancy

OBJECTIVES

To identify pretest characteristics of cerebrospinal fluid (CSF) specimens that will allow the rational use of flow cytometric analysis (FCA) in the diagnosis of hematologic malignancy.

METHODS

Retrospective data were collected on 501 consecutive CSF samples submitted for FCA.

RESULTS

A positive diagnosis of hematologic malignancy was made in 41 specimens (8.2%). Blasts or atypical lymphocytes were noted on Wright-stained slides in 98% of FCA-positive specimens (40/41), and a history of a hematologic malignancy was present in 89% of specimens (34/38). All FCA-positive specimens had atypical morphology or history of hematologic malignancy. Four hundred six specimens (81%) were FCA negative. Of FCA-negative specimens, 7% (30/406) had atypical morphology, and 3% (12/404) had future central nervous system involvement seen within 30 days.

CONCLUSIONS

These data support a policy in which FCA of CSF is actively discouraged unless atypical lymphocytes or blasts are seen or a history of hematologic malignancy is present.

Three cases of neoplastic meningitis initially diagnosed with infectious meningitis in emergency department

Neoplastic meningitis (NM) is diagnosed by the presence of malignant cells in the cerebrospinal fluid (CSF). We report 3 patients with NM, who were misdiagnosed with infectious meningitis in emergency department (ED). Case 1. A 68-year-old man visited our ED with a 3-month history of headache. With MRI and CSF study, he was diagnosed with tuberculous meningitis. After 20 days, repeated CSF cytology showed malignant cells. His diagnosis was lung cancer with NM. Case 2. A 57-year-old man visited regional hospital ED with a 3-week history of headache and diplopia. Brain MRI was not contributory. With CSF examination, his diagnosis was aseptic meningitis. With worsening headache, he was referred to our ED. Repeated CSF showed malignant cells. His diagnosis was stomach cancer with NM. Case 3. A 75-year-old man visited a regional hospital with headache lasting for 4 months. His diagnosis was sinusitis. Persistent symptom brought him back, and he developed recurrent generalized seizures. Brain MRI showed diffuse leptomeningeal enhancement suggesting meningitis, and he was transferred to our ED. CSF exam showed malignant cells. His diagnosis was NM with unknown primary focus. When evaluating the patients with headache in ED, NM should be kept in mind as a differential diagnosis of meningitis.

Rare cell capture technology for the diagnosis of leptomeningeal metastasis in solid tumors

OBJECTIVE

To evaluate the utility of rare cell capture technology (RCCT) in the diagnosis of leptomeningeal metastasis (LM) from solid tumors through identification of circulating tumor cells (CTCs) in the CSF.

METHODS

In this pilot study, CSF samples from 60 patients were analyzed. The main patient cohort consisted of 51 patients with solid tumors undergoing lumbar puncture for clinical suspicion of LM. Those patients underwent initial MRI evaluation and had CSF analyzed through conventional cytology and for the presence of CTCs using RCCT, based on immunomagnetic platform enrichment utilizing anti-epithelial cell adhesion molecule antibody-covered magnetic nanoparticles. An additional 9 patients with CSF pleocytosis but without solid tumors were separately analyzed to ensure accurate differentiation between CTCs and leukocytes.

RESULTS

Among the 51 patients with solid tumors, 15 patients fulfilled criteria for LM. CSF CTCs were found in 16 patients (median 20.7 CTCs/mL, range 0.13 to >150), achieving a sensitivity of 100% as compared with 66.7% for conventional cytology and 73.3% for MRI. One patient had a false-positive CSF CTC result (specificity = 97.2%); however, that patient eventually met LM criteria 6 months after the tap. CSF CTCs were not found in any of the additional 9 patients with CSF pleocytosis.

CONCLUSION

RCCT is an accurate, novel method for the detection of LM in solid tumors, potentially providing earlier diagnostic confirmation and sparing patients from repeat lumbar punctures.

Detection of cancer cells in the cerebrospinal fluid: current methods and future directions

The spread of cancer into the central nervous system is a serious problem leading to neurological symptoms and rapid mortality. The current tools available for detecting the spread of cancer into the cerebrospinal fluid (CSF) are cytology, neurologic examination, and neuroimaging. All three of these methods can be applied in concert to reach a diagnosis, but they all suffer from a lack of sensitivity, leading to delays in treatment in many cases. An overview of research tools in the field of CSF cancer detection reveals a variety of promising technologies that can be used to answer questions about the biology of metastatic cancer and to develop more powerful clinical detection methods. Methods currently under investigation include new immunocytochemistry methods and flow cytometry for the in vitro detection of cells. Additionally, polymerase chain reaction, fluorescence in situ hybridization, capillary electrophoresis with laser-induced fluorescence, and mass spectrometry using matrix-assisted laser absorption-deionization time-of-flight and surface-enhanced laser desorption/ionization time-of-flight techniques are being tested for in vitro assessment of the non-cellular biomarkers in CSF. For in vivo detection of cancer in the CSF, research techniques include certain quantum dot platforms as well as magnetic iron oxide nanoparticles. As systemic therapies for cancer improve, the CNS is becoming a more common site of disease recurrence. This increases the importance of effective detection methods in the CSF, since early intervention can maximize therapeutic benefit. Furthermore, many cell-based detection methods can be combined with therapeutic agents to serve multiple medical functions through a common targeting system.

Headache in patients with cancer

Contemporary cancer research has led to unparalleled advances in therapeutics and improved survival. Even as treatment options continue to improve, quality of life should remain a priority. Headache drastically impacts the quality of life of patients with cancer and has a wide etiological scope, making diagnosis a challenge. Intracranial mass lesions are only one cause; others include extracranial tumors, paraneoplastic processes, and the consequences of diagnostic and therapeutic interventions used in cancer care. Fortunately, cancer-related headache is treatable, but a sound understanding of the variable etiologies is crucial to appropriate diagnostic evaluation and treatment. In this review, we highlight the important causes of headache in the patient with cancer, and consider the epidemiology, pathophysiology, clinical course, and treatment options for each.

Diagnostic tools for neoplastic meningitis: detecting disease, identifying patient risk, and determining benefit of treatment

Three methods are routinely used to diagnose neoplastic meningitis (NM): clinical signs and symptoms, cerebrospinal fluid (CSF) cytology, and magnetic resonance imaging (MRI) of the brain and spine. Clinical manifestations are often subtle or may be ascribed to other cancer complications, eg, treatment-related disorders or brain parenchymal metastases. CSF cytology has a high specificity (>95%), but its sensitivity is generally less than 50%. MRI sensitivity and specificity vary with the type of primary cancer; overall, MRI findings consistent with leptomeningeal disease are detected in fewer than 50% of NM patients. While most clinicians evaluate CSF cytology along with MRI and the clinical examination, underdiagnosis is a major problem, since many patients are both cytologically and radiographically negative. Failure to consider NM in the differential diagnosis magnifies the problem of underdiagnosis. CSF flow cytometry is particularly promising for evaluating NM from hematologic cancers, with a diagnostic sensitivity many fold greater than conventional cytology. Research has focused on identifying biochemical markers of tumor cells in the CSF. For example, molecules involved in CNS penetration (eg, matrix metalloproteinases and cathepsins), tumor cell tropism (eg, chemokines CXCL8 and CCL18), and angiogenesis (eg, vascular endothelial growth factor) are elevated in the CSF of patients with NM. Evidence that some tumor types are more likely to infiltrate the CNS also has stimulated research into primary tumor markers predictive of CNS metastases. At present, there is no tumor marker or patient characteristic that reliably predicts the development of NM, and diagnosis still relies on suggestive signs and symptoms, positive CSF cytology, or a consistent MRI-all late manifestations of NM. Until techniques capable of detecting NM early are developed, increased awareness of the disease and standardized evaluation are likely to have the greatest impact on improving diagnosis and implementing earlier treatment.

Metastatic craniopharyngioma: case report and literature review

BACKGROUND

Distant spread of craniopharyngioma is a rare but important complication. Most cases are a result of spread along the surgical path. We describe a rare case of metastatic leptomeningeal craniopharyngioma as a result of dissemination along CSF pathways in a child. A review of previously described cases is provided.

CASE PRESENTATION

A 14-year-old male was diagnosed with metastatic craniopharyngioma on routine follow-up imaging after multiple surgeries and radiation for locally recurrent craniopharyngioma. The lesion was erosive through the right parietal bone, but had remained clinically silent. The lesion was distant from previous surgical paths. The patient underwent right parietal craniotomy and resection of the lesion. Duraplasty and cranioplasty were necessary for closure. Histopathology confirmed adamantinomatous craniopharyngioma. One-year follow-up demonstrated no recurrence.

DISCUSSION

A review of reported cases suggests that leptomeningeal implantation may be an important step in metastases of craniopharyngioma, although the mechanism is poorly understood. Attention to tumor spillage at the time of surgery may be important in preventing distant recurrences.

Peripheral nervous system involvement in patients with cancer

Involvement of the peripheral nervous system (PNS) is common in patients with cancer and any part, including motor neurons, sensory ganglia, nerve roots, plexuses, cranial and peripheral nerves, and neuromuscular junctions, can be affected. Different mechanisms can initiate damage associated with cancer-related PNS disorders. These include tumour infiltration, toxicity of treatments, metabolic and nutritional perturbations, cachexia, virus infections, and paraneoplastic neurological syndromes. The type of cancer, lymphoma, or solid tumour is a further determinant of a PNS disorder. In this Review we discuss the different causes and mechanisms of disorders of the PNS in patients with cancer and we will focus on their assessment and diagnosis.