Peripheral neuropathy and cancer

Cancer and Peripheral Nerve Disease

Patients with cancer may experience neuropathy at any stage of malignancy, ranging from symptoms that are the earliest signs of cancer to side effects of treatment. Peripheral nerves are affected most commonly in a symmetric, stocking-glove pattern. Sensory neuronopathies, plexopathies, and radiculopathies may also be seen. The most common type of neuropathy in patients with cancer is related to chemotherapy, and recently peripheral nerve complications have been described as an effect of immune checkpoint inhibitors too. Other causes include paraneoplastic syndromes, direct tumor infiltration, and radiation. Treatment focuses on addressing the underlying cancer and management of neuropathic pain.

Neuropathic pain at diagnosis of head and neck squamous cell carcinoma

OBJECTIVE

To assess the prevalence and characteristics of neuropathic pain (NP) at diagnosis of head and neck squamous cell carcinoma (HNSCC) and its impact on nutritional status and treatment tolerance.

MATERIALS AND METHODS

Patients treated for HNSCC between January 1, 2018 and January 30, 2019 were included. Pain was assessed prospectively on the DN2 and NSPI scales. Epidemiological characteristics, nutritional status and treatment tolerance were collected. Two groups were distinguished according to absence or presence of neuropathic pain (NP-, NP+).

RESULTS

Sixty patients were included. NP prevalence at diagnosis was 54%, mainly involving locally advanced oral cavity and oropharyngeal tumors. There was a significant intergroup difference in nutritional status, with 62% malnutrition in NP+ versus 32% in NP- (p=0.0321). There was no such difference in tolerance.

CONCLUSION

NP is frequent at diagnosis of HNSCC. Early diagnosis on a simple validated score can help improve quality of life and nutritional status.

Establishment of a murine pancreatic cancer pain model and microarray analysis of pain‑associated genes in the spinal cord dorsal horn

There is emerging evidence on the mechanisms of pancreatic cancer pain. Following the establishment of an orthotropic transplantation model of pancreatic cancer, microarray analysis was performed to identify changes in the expression levels of pain-associated genes in the spinal cord. A mouse model of pancreatic cancer-induced pain was established by implanting SW 1990 cells into the pancreases of female BALB/c-nu mice. The survival rate and body weight were measured following orthotropic transplantation. Gross anatomical techniques and hematoxylin and eosin staining were used to analyze the pancreatic tumor tissue. Multiple behavioral tests were also performed to assess pain-associated responses. Additionally, using samples from mice with or without observable pain, microarray analysis was performed to determine the gene expression profiles in the spinal cord dorsal horn. The survival rate of mice with pancreatic cancer was high during the initial 3 weeks post-surgery, although the body weight decreased progressively. Gross anatomical techniques demonstrated that the tumor size increased significantly following the surgery, and this result was confirmed by solid tumor masses in the pancreatic tissues of the mouse model. Observable pain behavioral responses were also examined in the pancreatic cancer model by measuring the mechanical threshold of the abdominal skin, hunching behavior and visceromotor responses. The profiles of 10 pain specific-associated genes in the spinal cord dorsal horn that accurately reflect the molecular pathological progression of disease were also identified. In conclusion, the present study has developed a novel animal model of pancreatic cancer pain in BALB/c-nu mice that resembles human pancreatic cancer pain, and the expression of pain-associated genes in the spinal cord dorsal horn has been profiled. The results of the present study may further the understanding of the molecular mechanisms that mediate pancreatic cancer pain.

Orofacial Pain in Cancer: Part I—Mechanisms

The mechanisms involved, and possible treatment targets, in orofacial pain due to cancer are poorly understood. The aim of the first of this two-part series is to review the involved pathophysiological mechanisms and explore their possible roles in the orofacial region. However, there is a lack of relevant research in the trigeminal region, and we have therefore applied data accumulated from experiments on cancer pain mechanisms in rodent spinal models. In the second part, we review the clinical presentation of cancer-associated orofacial pain at various stages: initial diagnosis, during therapy (chemo-, radiotherapy, surgery), and in the post-therapy period. In the present article, we provide a brief outline of trigeminal functional neuro-anatomy and pain-modulatory pathways. Tissue destruction by invasive tumors (or metastases) induces inflammation and nerve damage, with attendant acute pain. In some cases, chronic pain, involving inflammatory and neuropathic mechanisms, may ensue. Distant, painful effects of tumors include paraneoplastic neuropathic syndromes and effects secondary to the release of factors by the tumor (growth factors, cytokines, and enzymes). Additionally, pain is frequent in cancer management protocols (surgery, chemotherapy, and radiotherapy). Understanding the mechanisms involved in cancer-related orofacial pain will enhance patient management.

The Prevalence of Neuropathic Pain in Terminally Ill Patients With Cancer Admitted to a Palliative Care Unit: A Prospective Observational Study

OBJECTIVE

The primary aim of this study was to determine the prevalence of neuropathic pain (NP) in patients with cancer receiving palliative care.

METHODS

In this prospective observational study, terminally ill patients with cancer having NP were identified by a pain management clinician using the diagnostic algorithm of NP from the International Association for the Study of Pain on the day of admission.

RESULTS

A total of 220 patients who were hospitalized in the palliative care unit were enrolled in this study. The median survival times were 21.5 days (range, 0-173 days), and 57.7% of patients were male. Among the 220 patients, 41 (18.6%; 95% confidence interval, 13.5%-23.8%) developed NP.

CONCLUSION

The prevalence of NP in terminally ill patients with cancer in Japanese palliative care units was 18.6%.

Cancer Prevention and Therapy: Integrating Traditional Korean Medicine Into Modern Cancer Care

In spite of billions of dollars spent on cancer research each year, overall cancer incidence and cancer survival has not changed significantly in the last half century. Instead, the recent projection from the World Health Organization suggests that global cancer incidence and death is expected to double within the next decade. This requires an "out of the box" thinking approach. While traditional medicine used for thousands of years is safe and affordable, its efficacy and mechanism of action are not fully reported. Demonstrating that traditional medicine is efficacious and how it works can provide a "bed to bench" and "bench to bed" back approach toward prevention and treatment of cancer. This current review is an attempt to describe the contributions of traditional Korean medicine (TKM) to modern medicine and, in particular, cancer treatment. TKM suggests that cancer is an outcome of an imbalance of body, mind, and spirit; thus, it requires a multimodal treatment approach that involves lifestyle modification, herbal prescription, acupuncture, moxibustion, traditional exercise, and meditation to restore the balance. Old wisdoms in combination with modern science can find a new way to deal with the "emperor of all maladies."

Neuropathic pain in cancer

Cancer-related neuropathic pain is common; it can be disease related or related to the acute or chronic effects of cancer treatment. For example, chemotherapy-induced peripheral neuropathy occurs in 90% of patients receiving neurotoxic chemotherapy. Cancer treatments have become more effective; patients are living longer with cancer and there are more cancer survivors. However, side-effects (particularly neuropathy) have become more problematic. The key to management of cancer-related neuropathy is a considered assessment, remembering not to miss the opportunity of reversing the cause of the pain with appropriate oncological management. An increasing range of oncological therapies are available, including radiotherapy, chemotherapy, hormonal therapy, or one of the evolving approaches (e.g. immune therapies). Patients are often elderly and with comorbidities; therefore, all treatment decisions have to be made carefully and reviewed appropriately. Cancer pain is often of mixed aetiology or, if purely neuropathic, may be one of several pains experienced by a patient. For these reasons, opioids are used more frequently in patients with cancer-related neuropathic pain. Standard guidelines for the use of anticonvulsants (e.g. pregabalin and gabapentin), antidepressants (e.g. duloxetine and tricyclics), and topical treatments (e.g. capsaicin and lidocaine) may be applicable, but there is a lack of good-quality clinical trials in cancer-related neuropathic pain. Choice is dictated not just by age, drug interactions, and comorbidities, but also by the coexistence of many symptoms in patients with cancer. Treating more than one symptom with a particular neuropathic pain agent can avoid polypharmacy.

Management of painful neuropathies

Neuropathic pain is the most common type of pain in neuropathy. In painful polyneuropathies the pain usually has a "glove and stocking" distribution. The pain may be predominantly spontaneous, e.g., with a burning, pricking, or shooting character or characterized by evoked pain such as mechanical or cold allodynia. In the clinical setting, the prevention of painful neuropathies and treatment of underlying neuropathy remains inadequate and thus symptomatic treatment of the pain and related disability needs to be offered. Most randomized, double-blind, placebo-controlled trials (RCTs) published in painful neuropathy have been conducted in patients with diabetes and to what extent a treatment which is found effective in painful diabetic polyneuropathy can be expected to relieve other conditions like chemotherapy- or HIV-induced neuropathy is unknown. Tricyclic antidepressants (TCAs), gabapentin, pregabalin, and serotonin noradrenaline reuptake inhibitors (SNRIs) are first drug choices. In patients with localized neuropathic pain, a topical lidocaine patch may also be considered. Second-line treatments are tramadol and other opioids. New types of treatment include botulinum toxin type A (BTX-A), high-dose capsaicin patches, and cannabinoids. Other types of anticonvulsant drugs such as lamotrigine, oxcarbazepine, and lacosamide have a more questionable efficacy in painful polyneuropathy but may have an effect in a subgroup of patients. Combination therapy may be considered in patients with insufficient effect from one drug. Treatment is usually a trial-and-error process and has to be individualized to the single patient, taking into account all comorbidities such as possible concomitant depression, anxiety, diseases, and drug interactions. Side-effects to antidepressants include dry mouth, nausea, constipation, orthostatic hypotension, and sedation. ECG should always be obtained prior to treatment with TCAs, which also should not be used in patients with cardiac incompensation and epilepsy. The most common side-effects of gabapentin and pregabalin are CNS-related side-effects with dizziness and somnolence. Peripheral edema, weight gain, nausea, vertigo, asthenia, dry mouth, and ataxia may also occur. Topical treatments are better tolerated due to lack of systemic side-effects but there is still limited evidence for the long-term efficacy of these drugs. With available drugs, the average pain reduction is about 20-30%, and only 20-35% of the patients will achieve at least 50% pain reduction, which stresses the need of a multidisciplinary approach to pain treatment.

Pharmacological treatment of neuropathic cancer pain: a comprehensive review of the current literature

Neuropathic cancer pain (NCP), commonly encountered in clinical practice, may be cancer-related, namely resulting from nervous system tumor invasion, surgical nerve damage during tumor removal, radiation-induced nerve damage and chemotherapy-related neuropathy, or may be of benign origin, unrelated to cancer. A neuropathic component is evident in about 1/3 of cancer pain cases. Although from a pathophysiological perspective NCP may differ from chronic neuropathic pain (NP), such as noncancer-related pain, clinical practice, and limited publications have shown that these two pain entities may share some treatment modalities. For example, co-analgesics have been well integrated into cancer pain-management strategies and are often used as First-Line options for the treatment of NCP. These drugs, including antidepressants and anticonvulsants, are recommended by evidence-based guidelines, whereas, others such as lidocaine patch 5%, are supported by randomized, controlled, clinical data and are included in guidelines for restricted conditions treatment. The vast majority of these drugs have already been proven useful in the management of benign NP syndromes. Treatment decisions for patients with NP can be difficult. The intrinsic difficulties in performing randomized controlled trials in cancer pain have traditionally justified the acceptance of drugs already known to be effective in benign NP for the management of malignant NP, despite the lack of relevant high quality data. Interest in NCP mechanisms and pharmacotherapy has increased, resulting in significant mechanism-based treatment advances for the future. In this comprehensive review, we present the latest knowledge regarding NCP pharmacological management.

Vascularization of the dorsal root ganglia and peripheral nerve of the mouse: implications for chemical-induced peripheral sensory neuropathies

Although a variety of industrial chemicals, as well as several chemotherapeutic agents used to treat cancer or HIV, preferentially induce a peripheral sensory neuropathy what remains unclear is why these agents induce a sensory vs. a motor or mixed neuropathy. Previous studies have shown that the endothelial cells that vascularize the dorsal root ganglion (DRG), which houses the primary afferent sensory neurons, are unique in that they have large fenestrations and are permeable to a variety of low and high molecular weight agents. In the present report we used whole-mount preparations, immunohistochemistry, and confocal laser scanning microscopy to show that the cell body-rich area of the L4 mouse DRG has a 7 fold higher density of CD31+ capillaries than cell fiber rich area of the DRG or the distal or proximal aspect of the sciatic nerve. This dense vascularization, coupled with the high permeability of these capillaries, may synergistically contribute, and in part explain, why many potentially neurotoxic agents preferentially accumulate and injure cells within the DRG. Currently, cancer survivors and HIV patients constitute the largest and most rapidly expanding groups that have chemically induced peripheral sensory neuropathy. Understanding the unique aspects of the vascularization of the DRG and closing the endothelial fenestrations of the rich vascular bed of capillaries that vascularize the DRG before intravenous administration of anti-neoplastic or anti-HIV therapies, may offer a mechanism based approach to attenuate these chemically induced peripheral neuropathies in these patients.

The Total Neuropathy Score as an assessment tool for grading the course of chemotherapy-induced peripheral neurotoxicity: comparison with the National Cancer Institute-Common Toxicity Scale

Chemotherapy-induced peripheral neurotoxicity (CIPN) is a major side effect of several antineoplastic drugs. However, despite its clinical importance, there is no agreement as to the best way to assess the severity and changes in CIPN. We have previously demonstrated a correlation between the severity of CIPN, assessed using the Total Neuropathy Score (TNS) or its reduced versions, and several common toxicity scales. In this study, we investigated two series of patients (total number = 173) who were evaluated at baseline and during chemotherapy with the TNS (n= 122) or the TNSc (the TNS version based exclusively on the clinical evaluation of the patients, n= 51) and with the National Cancer Institute-Common Toxicity Criteria (NCI-CTC) 2.0, with the aim of comparing the sensitivity to the changes in CIPN severity. In both series, the TNS and the TNSc had a significant correlation with the NCI-CTC in scoring the severity of CIPN, confirming the results of previous studies. Moreover, both the TNS and the TNSc showed a higher sensitivity to CIPN changes. We, therefore, propose the TNSc as a reliable method for assessing not only the severity but also the changes in CIPN.

Cisplatin-induced peripheral neuropathy: Neuroprotection by erythropoietin without affecting tumour growth

This study examined the dose-dependent efficacy of erythropoietin (EPO) for preventing and/or treating cisplatin (CDDP) induced peripheral neurotoxicity (CINP), and its influence on tumour treatment and growth. Rats received eight intraperitoneal (ip) injections of 2 mg/kg CDDP twice weekly. EPO co-administered (50 or 10 microg/kg ip, three times/week) had a dose-dependent effect, partially preventing CINP, but 0.5 microg/kg ip was not effective. The neuroprotective effect lasted at least 5 weeks after the last dose of EPO and CDDP. In addition, EPO (50 microg/kg ip three times/week) after the last injection of CDDP still induced a significant recovery of CINP. In a separate experiment in rats bearing mammary carcinoma EPO treatment (50 microg/kg ip) given concurrently with CDDP (1.0 and 1.5 mg/kg twice a week for four weeks) was neuroprotective without influencing the effectiveness of the treatment or tumour growth. EPO thus appears to be an effective neuroprotectant that does not interfere with tumour treatment.

Chemotherapy-induced peripheral neuropathy: underreported and underappreciated

Chemotherapy-induced neuropathy is one of the most serious non-life-threatening side effects experienced by patients receiving this group of pharmaceutical agents. Although frequently reversible, some patients may remain with symptoms for the remainder of their lives. Early recognition that "numbness and tingling" in the hands and feet of a patient receiving chemotherapy is due to the antineoplastic drug, with subsequent dose reduction or discontinuation of the offending agent, may prevent the development of serious neurologic dysfunction.

Chemotherapy-induced neuropathy

Increasingly, surgeons are becoming aware of the successful treatment of symptomatic peripheral neuropathy by surgical decompression of peripheral nerves. Armed with the knowledge that patients can have underlying neuropathy with overlying anatomic compressions, surgeons have affected improvement in diabetes-induced neuropathy, neuropathy of unknown etiology, and chemotherapy-induced neuropathy. This article details the most well-known culprits in chemotherapy-induced neuropathy and discusses the putative mechanisms of action, medical management, and surgical data.