Neuropathic cancer pain: prevalence, pathophysiology, and management

Intravenous administration of recombinant Phα1β: Antinociceptive properties and morphine tolerance reversal in a cancer-associated pain model

Cancer-related pain is considered one of the most prevalent symptoms for those affected by cancer, significantly influencing quality of life and treatment outcomes. Morphine is currently employed for analgesic treatment in this case, however, chronic use of this opioid is limited by the development of analgesic tolerance and adverse effects, such as digestive and neurological disorders. Alternative therapies, such as ion channel blockade, are explored. The toxin Phα1β has demonstrated efficacy in blocking calcium channels, making it a potential candidate for alleviating cancer-related pain. This study aims to assess the antinociceptive effects resulting from intravenous administration of the recombinant form of Phα1β (r-Phα1β) in an experimental model of cancer-related pain in mice, tolerant or not to morphine. The model of cancer-induced pain was used to evaluate these effects, with the injection of B16F10 cells, followed by the administration of the r-Phα1β, and evaluation of the mechanical threshold by the von Frey test. Also, adverse effects were assessed using a score scale, the rotarod, and open field tests. Results indicate that the administration of r-Phα1β provoked antinociception in animals with cancer-induced mechanical hyperalgesia, with or without morphine tolerance. Previous administration of r-Phα1β was able to recover the analgesic activity of morphine in animals tolerant to this opioid. r-Phα1β was proved safe for these parameters, as no adverse effects related to motor and behavioral activity were observed following intravenous administration. This study suggests that the concomitant use of morphine and r-Phα1β could be a viable strategy for pain modulation in cancer patients.

Targeting TRPV4 Channels for Cancer Pain Relief

Despite the unique and complex nature of cancer pain, the activation of different ion channels can be related to the initiation and maintenance of pain. The transient receptor potential vanilloid 4 (TRPV4) is a cation channel broadly expressed in sensory afferent neurons. This channel is activated by multiple stimuli to mediate pain perception associated with inflammatory and neuropathic pain. Here, we focused on summarizing the role of TRPV4 in cancer etiology and cancer-induced pain mechanisms. Many studies revealed that the administration of a TRPV4 antagonist and TRPV4 knockdown diminishes nociception in chemotherapy-induced peripheral neuropathy (CIPN). Although the evidence on TRPV4 channels' involvement in cancer pain is scarce, the expression of these receptors was reportedly enhanced in cancer-induced bone pain (CIBP), perineural, and orofacial cancer models following the inoculation of tumor cells to the bone marrow cavity, sciatic nerve, and tongue, respectively. Effective pain management is a continuous problem for patients diagnosed with cancer, and current guidelines fail to address a mechanism-based treatment. Therefore, examining new molecules with potential antinociceptive properties targeting TRPV4 modulation would be interesting. Identifying such agents could lead to the development of treatment strategies with improved pain-relieving effects and fewer adverse effects than the currently available analgesics.

Pain management in cervical cancer

Cervical cancer (CC) occupies the second place in incidence and mortality among women in México. Despite this, Cervical Cancer continues to have a late diagnosis which leads to a high rate of complications. Pain represents the most feared and disabling symptom, being present in up to 86% of patients with advanced disease. The approach to managing pain in this population has not been studied and described to a full extent. In addition, there is a pressing need to provide concise recommendations to promote adequate pain control. We performed a review of the literature in CC and had experts in the field of pain management evaluate the evidence found. We then issued relevant recommendations on pharmacology and interventional pain management. Thus, the approach to pain management must be comprehensive and individualized, considering the timely and appropriate use of pharmacologic treatment as well as interventional procedures.

Effect of recombinant human epidermal growth factor on neuropathic pain associated with radiotherapy for head and neck malignancies and nursing strategy

OBJECTIVE

To evaluate the effect of recombinant human epidermal growth factor (rhEGF) on radiotherapy-related neuropathic pain in patients with head and neck malignancies, and to explore comprehensive nursing strategies.

METHODS

In this retrospective study, a total of 80 patients diagnosed with head and neck malignancy and receiving radiotherapy were divided into 2 groups according to treatment. Patients in the control group received conventional radiation therapy and postoperative care, and those in the trial group received rhEGF in addition to conventional radiation therapy and care. Visual analogue scale (VAS) was used to evaluate the pain degree of patients before and after treatment, EORTC QLQ-C30 scale was used to evaluate the quality of life of patients before and after treatment, and the skin and mucosal reactions of patients after radiotherapy were observed.

RESULTS

Baseline characteristics were similar between the two groups. VAS scores in the trial group were significantly lower than those in the control group during and after radiotherapy (p < 0.001), and skin and mucosal reactions were less severe (p < 0.05). In addition, compared with the control group, the quality of life and symptom scores of the trial group were significantly improved after treatment (p < 0.05).

CONCLUSION

rhEGF can effectively alleviate neuropathic pain during and after radiotherapy in patients with head and neck malignancies, improve skin and mucosal response, and improve quality of life.

Effect of Melissa officinalis on Chemotherapy-Induced Peripheral Neuropathy in Cancer Patients: A Randomized Trial

Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a significant cancer treatment side effect that can influence both quality of life and treatment course. Melissa Officinalis (MO), due to its high content of flavonoids, has antioxidant, anti-inflammatory, and neuroprotective properties.  Materials and Methods: The cancer patients diagnosed with CIPN attended a referral center in Sari (Iran). The hydroalcoholic extract of MO leaves was extracted by the maceration method. The control group received a placebo along with gabapentin as the standard treatment, and the intervention group received 500 mg Melissa officinalis 2 times daily for 3 months plus gabapentin. Patients were evaluated at the baseline and 3 months later, according to Common Terminology Criteria for Adverse Effects (CTCAE) and EORTC QLQ-C30 (Integrated System for Quality of Life Assessment).  Results: A total of 40 patients were considered as group D (intervention group), and 35 patients completed the study. Out of 40 subjects in the placebo group (P), 3 patients could not tolerate the drug due to gastrointestinal disturbances. The final values of CTCAE showed a statistically significant difference (p=0.010). Indicators related to the quality of life in both groups showed a significant improvement. In the intervention group, the pain perception and diarrhea experience were significantly reduced. Conclusion: Quality of life indicators were improved by prescribing gabapentin with and without Melissa officinalis. The addition of Melissa officinalis to the chemotherapy regimen may improve diarrhea and pain perception.

Transient Receptor Potential Channels: Multiple Modulators of Peripheral Neuropathic Pain in Several Rodent Models

Neuropathic pain, a prevalent chronic condition in clinical settings, has attracted widespread societal attention. This condition is characterized by a persistent pain state accompanied by affective and cognitive disruptions, significantly impacting patients' quality of life. However, current clinical therapies fall short of addressing its complexity. Thus, exploring the underlying molecular mechanism of neuropathic pain and identifying potential targets for intervention is highly warranted. The transient receptor potential (TRP) receptors, a class of widely distributed channel proteins, in the nervous system, play a crucial role in sensory signaling, cellular calcium regulation, and developmental influences. TRP ion channels are also responsible for various sensory responses including heat, cold, pain, and stress. This review highlights recent advances in understanding TRPs in various rodent models of neuropathic pain, aiming to uncover potential therapeutic targets for clinical management.

A Qualitative Study of the Pain Experience of Black Individuals With Cancer Taking Long-Acting Opioids

BACKGROUND

Little is known about the experience of Black individuals with cancer taking long-acting opioids for cancer pain.

OBJECTIVE

This study aimed to describe the day-to-day experience of living with pain and the experiences of taking opioids for pain management among Black individuals with cancer prescribed with long-acting opioids.

METHODS

This qualitative descriptive study was part of a larger investigation focused on opioid adherence. Participants (N = 14) were interviewed using a semistructured interview guide. Analysis followed conventional content analysis and constant comparison approaches. Sociodemographics, clinical information, and the Brief Pain Inventory form were collected.

RESULTS

The majority of the subsample was female (64.3%), not married (78.6%), and with a median age of 52.5 years. Participants were taking either MS Contin (85.7%) or OxyContin (14.3%). The Brief Pain Inventory median "average" pain severity scores and pain interference scores were 5.1/10 (interquartile range [IQR] = 6.1) and 3.5/10 (IQR = 6.7), respectively. Three themes are reported from the analyses: desire for control, barriers to pain relief, and isolation versus connectedness.

CONCLUSION

Our findings highlight the persistent nature of moderate to severe cancer pain and how pain and its treatment interfere with patients' lives. The findings describe ways that patients learn to manage and exert control over pain despite conflicting attitudes and dealing with opioid stigma.

IMPLICATION FOR PRACTICE

Clinicians should partner with patients with cancer, especially people of color, who may experience intersecting stigmas related to their cancer pain and opioid use, to best provide an individualized and culturally sensitive pain treatment plan.

From pain to tumor immunity: influence of peripheral sensory neurons in cancer

The nervous and immune systems are the primary sensory interfaces of the body, allowing it to recognize, process, and respond to various stimuli from both the external and internal environment. These systems work in concert through various mechanisms of neuro-immune crosstalk to detect threats, provide defense against pathogens, and maintain or restore homeostasis, but can also contribute to the development of diseases. Among peripheral sensory neurons (PSNs), nociceptive PSNs are of particular interest. They possess a remarkable capability to detect noxious stimuli in the periphery and transmit this information to the brain, resulting in the perception of pain and the activation of adaptive responses. Pain is an early symptom of cancer, often leading to its diagnosis, but it is also a major source of distress for patients as the disease progresses. In this review, we aim to provide an overview of the mechanisms within tumors that are likely to induce cancer pain, exploring a range of factors from etiological elements to cellular and molecular mediators. In addition to transmitting sensory information to the central nervous system, PSNs are also capable, when activated, to produce and release neuropeptides (e.g., CGRP and SP) from their peripheral terminals. These neuropeptides have been shown to modulate immunity in cases of inflammation, infection, and cancer. PSNs, often found within solid tumors, are likely to play a significant role in the tumor microenvironment, potentially influencing both tumor growth and anti-tumor immune responses. In this review, we discuss the current state of knowledge about the degree of sensory innervation in tumors. We also seek to understand whether and how PSNs may influence the tumor growth and associated anti-tumor immunity in different mouse models of cancer. Finally, we discuss the extent to which the tumor is able to influence the development and functions of the PSNs that innervate it.

Assessment of neuropathic pain following cancer treatment

Neuropathic cancer pain (NCP) is prevalent affecting up to 58% of those with persistent pain following cancer treatment. Neuropathic pain can develop from malignancy, after neural tissue insult during surgery and/or exposure to radiation or neurotoxic agents used as part of cancer treatment regimens. Pain following cancer treatment is commonly under-treated and one barrier identified is poor recognition of pain and inadequate assessment. Recognition of the presence of NCP is important to inform pain management, which is challenging to treat and warrants the use of specific treatments to target neuropathic mechanisms. In this review, approaches for screening and classifying NCP are described. These include screening questionnaires and the application of the updated neuropathic pain grading system in a cancer context. The evidence from neuropathic pain related assessments in cancer populations is provided and highlighted under different neuropathic pain grades. Recommendations for assessment in practice are provided.

Cancer Pain Management with Traditional Chinese Medicine: Current Status and Future Perspectives

Cancer pain, especially the moderate-to-severe pain experienced by patients with advanced cancer, is still one of the most challenging clinical problems. The current mainstream pharmacological treatment for cancer pain involves applying opioid medications and other pain-killing drugs. However, analgesic drugs have many adverse effects such as addiction, tolerance, and other formidable clinical and social issues. Thus, finding a new therapeutic approach to treat cancer pain is essential. Traditional Chinese medicine (TCM) has been increasingly applied in clinical practice because of its good efficacy and few side effects. However, its mechanisms of action in treating pain are still under investigation. The most important mechanism of cancer pain is that a large amount of pain-causing substances are secreted from cancer cells and promote their growth and invasion. The physical and chemical stimulations of these substances exist along with the cancer growth, leading to constantly increased pain sensation. Whether cancer pain can be alleviated by inhibiting cancer cells from releasing the substances and changing the microenvironment around the cancer mass, or even by eliminating pain-causing substances, is largely unknown. Based on TCM theory, this study reported that the aforementioned approach could effectively manage different cancer pains by tonifying qi, clearing and activating channels and meridians, and strengthening body resistance. The TCM therapies activate blood circulation, remove blood stasis, and nourish the heart. Commonly used Chinese herbal drugs include Corydalis yanhusuo, Angelica dahurica, and Ligusticum chuanxiong. Instead of using conventional analgesics to reduce pain, we should focus on using TCM modalities to alleviate cancer pain and increase the quality of life in patients suffering from cancer pain. TCM should provide us with a new strategy for managing cancer pain.

Incidence of Different Characters of Neuropathic Pain in Cancer Patients Coming to Tertiary Care Centre in North India Over A Period of 1 Year - An Observational Study

Objectives

Pain is classified as nociceptive, neuropathic, or nociplastic. Neuropathic pain presents as variable phenotypes (characters) based on specific aetiology and pathophysiology. This study aimed to find out among cancer patients the incidence of different phenotypes of neuropathic pain and form specific phenotypic clusters based on the underlying neurophysiology and association of sensory profile with various organ systems - A prospective observational study.

Materials and methods

The Institutional Ethical Committee clearance (IEC code: 2020-49-MD-EXP-15) https://ctri.nic.in/Clinicaltrials/showallp.php?mid1=44886&EncHid=88651.15716&userName=CTRI/2020/09/027964 approval was obtained. After written and informed consent, patients of age group 18-80 years, registering in the pain and palliative outpatient department or radiotherapy department with complaints of pain and not taking any anti-neuropathic pain medications, were enrolled. They were assessed using Leeds assessment of neuropathic symptoms and signs (LANSS) pain score, and a score of >12 was eligible for assessment of neuropathic pain phenotypes.

Results

Out of 210 cancer patients complaining of pain, a neuropathic component with LANSS >12 was found in 73 (34.76%). The most predominant phenotypes, allodynia> tingling> pricking = burning, were found in 72.60%, 56.16%, and 43.84% of patients, respectively. Phenotypes were clustered into Nodes 1 and 2 based on clinically significant separation of phenotypes. Node 1 had neuropathic pain of spontaneous origin found predominantly in gastrointestinal tract (GIT) and genitourinary tract (GUT) cancers. Node 2 had stimulus-evoked negative and positive characters which occurred in head and neck, thoracic, and spinal metastatic cancers.

Conclusion

Careful patient assessment reveals the incidence of neuropathic pain in 34.76%; allodynia and tingling astable the most prominent phenotypes. Broadly, sensory characters were clustered into spontaneous and stimulus-evoked sensations with GIT and GUT cancers presenting with Node 1 symptoms.

Evaluation of Gabapentin as a Treatment of Breakthrough Cancer Pain Caused by Metastatic Prostate Adenocarcinoma

Introduction

Breakthrough Cancer Pain (BTcP) is defined as a temporary increase in pain that occurs spontaneously. The use of gabapentin is believed to be able to reduce pain complaints in patients with BTcP. However, research to support the efficacy of gabapentin in relieving pain in patients with BTcP is still limited. This study aims to determine the effectiveness of the use of gabapentin in patients with BTcP caused by metastatic prostate adenocarcinoma.

Methods

The study was conducted by analytic study with a prospective approach. The subjects were all patients with metastatic prostate adenocarcinoma at Zainoel Abidin General Hospital during 2022-2023 which fulfilled inclusion and exclusion criteria (30 patients). Data analysis was performed in the form of reduction in pain scale in patients with BTcP caused by metastatic prostate adenocarcinoma using gabapentin and the combination of the opioid gabapentin with T-Test.

Results

The results showed that there was no significant difference between the reduction in posttreatment pain in patients with BTcP caused by metastatic prostate adenocarcinoma taking gabapentin alone or taking the opioid gabapentin combination, either on days 3-4 or on days 5-6 (p > 0.05). However, based on the results of the evaluation on day 3-4, it was found that gabapentin was able to reduce pain by 2.2272, whereas the combination of opioid gabapentin was only able to reduce pain by 1.916. The evaluation on days 5-6 showed that gabapentin was able to reduce pain by 4.1363 and the combination of gabapentin opioids by 3.2083.

Conclusion

The conclusion of this research is that gabapentin is effective in the treatment of BTcP caused by metastatic prostate adenocarcinoma.

Cebranopadol for the Treatment of Chronic Pain

PURPOSE OF REVIEW

Regardless of the etiology, if pain persists chronically, it can detrimentally impact multiple aspects of a patient's well-being. Both physical and psychological effects are significant in many chronic pain patients. In this regard, psychological consequences can alter a patient's quality of life, functionality, and social functioning. Opioids have been the long-established gold standard for acute pain treatment in settings such as the postoperative period. An alternative to opioids in pain management has been highly sought after. Through a non-selective mechanism, cebranopadol is a first-in-class oral drug which combines agonism of the mu and nociceptin opioid peptide (NOP) receptors to provide improved analgesia, while reducing the occurrence of many typically opioid side effects. This manuscript is a narrative review of the possible use of cebranopadol in pain management.

RECENT FINDINGS

In pre-clinical studies, cebranopadol was similar to morphine in its pain control efficacy. In a phase IIa trial, cebranopadol was superior to placebo in reducing pain. In a randomized clinical trial, cebranopadol was superior to morphine. Another study concluded that cebranopadol had a lower misuse potential when compared to hydromorphone. In summary, cebranopadol offers new opportunities in treating chronic moderate to severe pain, while also countering risks of addiction. Additional studies are warranted to further evaluate the safety and efficacy of cebranopadol. In this regard, cebranopadol could prove to be a promising alternative to current pain treatment options.

Pharmacologic Management of Cancer-Related Pain in Pregnant Patients

Despite being an essential part of whole-person care, patients with cancer often experience complex and under-treated pain. Managing cancer-related pain in patients who are also pregnant compounds the challenge for adequate pain management, as studies have largely excluded this population. Therapy for pain management should be guided by the cause and mechanism of pain. The objective of this review is to provide clinicians with an understanding of pain experienced by pregnant patients with cancer and medications that may be used to help manage cancer-related pain. Nociceptive pain results from damage to somatic or visceral tissues that may be directly caused by cancer. This type of pain can be managed in pregnant patients using acetaminophen and/or nonsteroidal antiinflammatory drugs as first-line agents. In nociceptive pain not managed by non-opioid analgesics, buprenorphine is recommended for those requiring chronic opioids to help manage their pain. Neuropathic pain that results from damage to the peripheral or central nervous system may also be directly caused by cancer, particularly chemotherapy. In pregnant patients, duloxetine and gabapentin should be considered first. Venlafaxine, pregabalin, tricyclic antidepressants, and sodium channel blockers should be avoided, if possible. Nociplastic pain is not directly caused by cancer but may be caused by ongoing peripheral nociceptive input or a condition that predates the cancer diagnosis. Duloxetine and gabapentin are reasonable agents to consider for treatment of nociceptive pain in pregnant patients. Cyclobenzaprine may also be helpful for nociplastic pain.

Enhanced acupuncture therapy for radiotherapy-related neuropathic pain in patients with gynecologic cancer: a report of two cases and brief review

As radiation therapy is increasingly utilized in the treatment of cancer, neuropathic pain (NP) is a common radiotherapy-related adverse effect and has a significant impact on clinical outcomes negatively. However, despite an improved understanding of neuropathic pain management, pain is often undertreated in patients with cancer. Herein, we reported two cases with radiotherapy-related neuropathic pain (RRNP) who presented a positive reaction to acupuncture. Patient 1 (a 73-year-old woman) with gynecologic cancer complained of burning and electric shock-like pain in the lower limb after radiotherapy. With the accepted combination of acupuncture and drugs, the pain was alleviated completely in 8 weeks. Patient 2 (a 64-year-old woman) accepted acupuncture in the absence of medication because of her inability to tolerate the adverse events of anticonvulsant drugs. She achieved remission of pain 4 weeks later. The results of this study showed that acupuncture might be promising for controlling the RRNP in patients with cancer, especially who were intolerant or unresponsive to medications.

Exercise-based rehabilitation on functionality and quality of life in head and neck cancer survivors. A systematic review and meta-analysis

Head and Neck Cancer (HNC) is a globally rare cancer that includes a variety of tumors affecting the upper aerodigestive tract. It presents with difficulty breathing or swallowing and is mainly treated with radiation therapy, chemotherapy, or surgery for tumors that have spread locally or throughout the body. Alternatively, exercise can be used during cancer treatment to improve function, including pain relief, increase range of motion and muscle strength, and reduce cancer-related fatigue, thereby enhancing quality of life. Although existing evidence suggests the adjunctive use of exercise in other cancer types, no previous studies have examined the effects on HNC survivors. The aim of this meta-analysis was to quantify the effect of exercise-based rehabilitation on functionality and quality of life in HNC survivors who underwent surgery and/or chemoradiotherapy. A systematic review and meta-analysis were carried out following PRISMA statement and registered in PROSPERO (CRD42023390300). The search was performed in MEDLINE (PubMED), Cochrane Library, CINAHL and Web of Science (WOS) databases from inception to 31st December 2022 using the terms "cancer", "head and neck neoplasms", "exercise", "rehabilitation", "complications", "muscle contraction", "muscle stretching exercises" combining with booleans "AND"/"OR". PEDro scale, Cochrane Risk of Bias Tool and GRADE were used to assess methodological quality, risk of bias and grade of recommendation of included studies respectively. 18 studies (n = 1322) were finally included which 1039 (78.6%) were men and 283 (21.4%) were women. In patients who underwent radio-chemotherapy, overall pain [SMD = - 0.62 [- 4.07, 2.83] CI 95%, Z = 0.35, p = 0.72] and OP [SMD = - 0.07 [- 0.62, 0.48] CI 95%, Z = 0.25, p = 0.81] were slightly reduced with exercise in comparison to controls. Besides, lower limb muscle strength [SMD = - 0.10 [- 1.52, 1.32] CI 95%, Z = 0.14, p = 0.89] and fatigue [SMD = - 0.51 [- 0.97, - 0.057] CI 95%, Z = 2.15, p < 0.01] were also improved in those who receive radio-chemoradiation. In HNC survivors treated with neck dissection surgery, exercise was superior to controls in overall pain [SMD = - 1.04 [- 3.31, 1.23] CI 95%, Z = 0.90, p = 0.37] and, in mid-term, on shoulder pain SMD = - 2.81 [- 7.06, 1.43] CI 95%, Z = 1.76, p = 0.08]. No differences in quality of life were found at any of the follow-up periods. There is evidence of fair to good methodological quality, low to moderate risk of bias, and weak recommendations supporting the use of exercise-based rehabilitation to increase functionality. However, no evidence was found in favor of the use of this modality for improving the quality of life of HNC survivors who underwent chemoradiotherapy or surgery.

Microbiological and Physiological Effects of Pain

Pain is an important innate defense mechanism that can dramatically alter a person's quality of life. Understanding the microbiological and physiological effects of pain may be important in the pursuit of novel pain interventions. The three descriptors of pain recognized by the International Association for the Study of Pain are nociceptive, neuropathic, and nociplastic pain. Our review examined the current understanding of all three pain types, focusing on the key molecules involved in the manifestation of each type as well as physiological effects. Additionally, we compared the differences in painful and painless neuropathies and discussed the neuroimmune interaction involved in the manifestation of pain.

Intrathecal drug delivery for cancer pain at the end of life: a case study

Two-thirds of patients with advanced cancer have pain and, of these, approximately 10-20% do not respond to conventional pain management approaches. This case study concerns a hospice patient who received intrathecal drug delivery for intractable cancer pain at the end of life. This involved working in partnership with a hospital-based interventional pain team. Despite side-effects and complications associated with intrathecal drug delivery and the requirement for inpatient nursing care, intrathecal drug delivery was the best option for the patient. The case identifies the importance of a patient-centred approach to decision-making, effective partnerships between hospice and acute hospital teams, and nurse education as key factors contributing to the provision of safe and effective intrathecal drug delivery.

Global research trends of acupuncture therapy on cancer pain: A bibliometric and visualized study

Background

The number of publications on acupuncture for cancer pain is increasing rapidly with an upward tendency. Considering that no bibliometric articles related to this topic have been published yet. It is necessary to evaluate the global scientific output of research in this field, and shed light on the direction of clinical cancer pain management in the future.

Methods

Research publications regarding acupuncture on cancer pain from inception to 2022 were downloaded from the Web of Science Core Collection. Bibliometric analyses were performed using CiteSpace software, the bibliometrix R package, and VOSviewer software. Network maps were generated to assess the collaborations between different countries, institutions, authors, and keywords. And clusters map was generated to evaluate reference.

Results

A total of 790 articles related to acupuncture therapy for cancer pain were identified. We observe that the number of publications is gradually increasing over time. China and the United States were the main contributors. Mem Sloan Kettering Canc Ctr (38 papers) and Beijing Univ Chinese Med (28 papers) contributed the most publications, becoming the leading contributors in this field. Although J Clin Oncol (28 articles) ranked ninth in terms of publication volume, it was the journal with the most citations and the highest number of IF (50.717) and H-index (494) at the same time. MAO J from Mem Sloan Kettering Canc Ctr was the most prolific author (23 articles). The main hot topics included matters related to acupuncture (239 times), pain (199 times), management (139 times), quality of life (107 times), electroacupuncture (100 times), and breast cancer (82 times).

Conclusion

Our bibliometric analysis provides a comprehensive overview of the development of acupuncture for cancer pain, enabling relevant authors and research teams to identify the current research status in this field. At the same time, acupuncture for breast cancer (BC) pain, aromatase inhibitor-induced arthralgia (AIA), and chemotherapy-induced peripheral neuropathy (CIPN) may soon become prospective focus.

Topical Traditional Chinese Medicines for Cancer Pain: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND AND OBJECTIVES

Safe and effective management of cancer-related pain is a worldwide challenge. In the search for treatment options, natural products used in Chinese herbal medicines (CHMs) have received attention in clinical studies for their effects on cancer-related pain. The objective of this systematic review is to evaluate the clinical evidence for topically applied CHMs as adjunctive treatments for cancer pain management.

METHODS

Nine biomedical databases and 4 clinical trial registries were searched for randomized-controlled trials (RCTs) that reported measures of pain and/or quality of life. Risk of bias was assessed using the Cochrane tool. Meta-analysis employed mean difference (MD) with 95% confidence intervals (random effects).

RESULTS

Twenty (20) RCTs (1636 participants) met the inclusion criteria. Meta-analyses were grouped based on the comparisons and outcome measures. For pain intensity, there was a greater reduction in the topical CHM group versus placebo (MD -0.72 [-1.04, -0.40]), no difference when compared to tramadol (MD -0.15 [-0.38, 0.08]), and a greater reduction when topical CHMs were combined with conventional analgesic medications (MD -0.67 [-0.93, -0.40]). Analgesic onset time was reduced in the CHM group compared to tramadol (MD -26.02 [-27.57, -24.47] minutes), and for CHMs combined with conventional medications (MD -19.17 [-21.83, -16.52] minutes). When CHMs were combined with analgesic medications, improvements were found for duration of analgesia (MD 1.65 [0.78, 2.51] hours), analgesic maintenance dose (MD -31.72 [-50.43, -13.01] milligrams/day), and quality of life.

CONCLUSION

Addition of topical CHMs to conventional analgesic medications was associated with improved outcomes for pain intensity, some other pain-related outcomes, and measures of quality of life. Limitations included methodological issues in some studies and considerable heterogeneity in some pooled results.

Potential Roles of 5-HT3 Receptor Antagonists in Reducing Chemotherapy-induced Peripheral Neuropathy (CIPN)

5-HT₃ receptor antagonists corresponding to ondansetron, granisetron, tropisetron, and palonosetron are clinically accustomed to treating nausea and emesis in chemotherapy patients. However, current and previous studies reveal novel potentials of those ligands in other diseases involving the nervous system, such as addiction, pruritus, and neurological disorders, such as anxiety, psychosis, nociception, and cognitive function. This review gathers existing studies to support the role of 5-HT₃ receptors in CIPN modulation. It has been reported that chemotherapy drugs increase the 5-HT content that binds with the 5-HT₃ receptor, which later induces pain. As also shown in pre-clinical and clinical studies that various neuropathic pains could be blocked by the 5-HT₃ receptor antagonists, we proposed that 5-HT₃ receptor antagonists via 5- HT₃ receptors may also inhibit neuropathic pain induced by chemotherapy. Our review suggests that future studies focus more on the 5-HT₃ receptor antagonists and their modulation in CIPN to reduce the gap in the current pharmacotherapy for cancer-related pain.

Feasibility and potential effects of breathing exercise for chronic pain management in breast cancer survivors: study protocol of a phase II randomised controlled trial

INTRODUCTION

Chronic pain is a common symptom significantly affecting the quality of life of breast cancer survivors. Despite the achievement of pharmacological interventions, the barriers associated with this approach such as inaccessibility, misuse and side effects drive research into effective non-pharmacological interventions to improve chronic pain management, quality of life, anxiety and depression. Breathing exercise (BE) can be a promising option, but research evidence is sparse. This pilot study aims to examine the feasibility and preliminary effect of using an evidence-based BE intervention for chronic pain management in breast cancer survivors.

METHOD AND ANALYSIS

This study will be a two-parallel-arm, open-labelled, phase II randomised controlled trial with 1:1 allocation. Seventy-two participants will be recruited from a tertiary hospital in China and randomly allocated to either a BE intervention group (n=36) or a control group (n=36). The participants in the intervention group will receive the usual care, a pain information booklet and a 4-week self-administered BE intervention; the participants in the control group will receive the usual care and the pain information booklet only. The assessment will be conducted at three time points: baseline (week 0), immediately after the intervention completion (week 5) and 4 weeks after the intervention completion (week 9). The primary outcomes will be the acceptability and feasibility assessment of the study protocol and methodological procedures. The secondary outcomes will be the effects of BE on pain, quality of life, anxiety and depression in breast cancer survivors. Descriptive statistics will be applied to present the primary outcomes and the Generalised Estimating Equation Model will be utilised to analyse the clinical outcomes.

ETHICS AND DISSEMINATION

This study has received ethical approvals from the Human Research Ethics Committee at Charles Darwin University (H21089) and the Clinical Trial Ethics Committee at the Affiliated Hospital of Southwest Medical University (KY2022107). Findings from this study will be presented at academic conferences and submitted to peer-reviewed journals for publication.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT05257876.

Validity Testing of the Head and Neck Lymphedema and Fibrosis Symptom Inventory

Background: Lack of reliable and valid tools significantly impacts early identification and timely treatment of lymphedema and fibrosis (LEF) in the head and neck cancer population. To address this need, we developed and reported a patient-reported outcome measure (Head and Neck Lymphedema and Fibrosis Symptom Inventory [HN-LEF SI]). This article reports the construct validity (convergent and divergent validity) testing of the tool. Materials and Methods: A prospective, longitudinal, instrument validation study was conducted in patients with a newly diagnosed oral cavity or oropharyngeal cancer. Participants completed the HN-LEF SI and six carefully selected self-report measures at pretreatment, end-of-treatment, and every 3 months up to 12 months after treatment. Spearman correlations were used. Results: A total of 117 patients completed the study. Patterns of correlations of the HN-LEF SI scores with the established self-report measure scores were consistent with expected convergent and divergent validity. Conclusion: Evidence from this work supports the construct validity of the HN-LEF SI.

Effects of an Intrathecal Drug Delivery System Connected to a Subcutaneous Port on Pain, Mood and Quality of Life in End Stage Cancer Patients: An Observational Study

BACKGROUND

In cancer patients with limited life expectancy, an implant of an intrathecal (IT) drug delivery system connected to a subcutaneous port (IDDS-SP) has been proposed as a successful strategy, but conflicting results are reported on quality of life (QoL). The aim of this prospective observational study is to report the effects on pain, mood and QoL of an IT combination therapy delivered by an IDDS-SP in malignant refractory pain.

METHODS

Adult patients in which IT therapy was recommended were recruited. An IT therapy with morphine and levobupivacaine was started: VASPI score, depression and anxiety (evaluated by the Edmonton Symptom Assessment System -ESAS-), the Pittsburgh Sleep Quality Index (PSQI), the 5-level EuroQol 5D version (EQ-5D-5L) and the requirements of breakthrough cancer pain (BTcP) medications were registered, with adverse events rate and the satisfaction of patients scored as Patient Global Impression of Change (PGIC).

RESULTS

Fifty patients, (16 F/34 M) were enrolled (age 69 ± 12). All had advanced cancer with metastasis. The median daily VASPI score was 75, the median depression score was 6, and the median anxiety score was 4, median PSQI was 16. At 28 days, a significant reduction in VASPI score was registered as well as in depression and anxiety item. Also, PSQI decreased significantly. The EQ-5D-5 L showed a significant improvement in all components at 14 and 28 days. Patient Global Impression of Change scores showed high level of satisfaction. A low incidence of adverse events and a reduction in BTCP episodes were also registered.

CONCLUSION

Intrathecal combination therapy delivered by an IDDS-SP could ensure adequate control of cancer related symptoms, such as pain, depression, anxiety and sleep disturbances. These effects, with low rate of AEs and reduced BTcP episodes, could explain the improvement in QoL and the overall high levels of patients' satisfaction.

Incidence, risk factors, prevention and treatment of postmastectomy pain syndrome in breast cancer: A multicenter study

BACKGROUND

Postmastectomy pain syndrome (PMPS) is a common postoperative condition after breast cancer surgery.

PURPOSE

The aim of this study was to investigate the incidence rate and risk factors of PMPS, and to propose prevention and treatment methods.

METHODS

The study included 1790 postoperative breast cancer patients from three hospitals from 2017 to 2021, of which 302 (13.0%) patients with PMPS were included in the study.

RESULTS

Age, breast surgery type, axillary surgery type and radiotherapy are the risk factors of PMPS. Age, radiotherapy and chemotherapy affect the pain degree of PMPS during movement.

CONCLUSIONS

For breast cancer patients with high risk factors, pain should be actively prevented during perioperative period. Oral pharmacological agents, multidisciplinary combination therapy, local anesthetics and regional anesthesia are the most common treatment of PMPS.

Neuropathic pain prevalence and risk factors in head and neck cancer survivors

BACKGROUND

Neuropathic pain (NP) is a debilitating symptom among head and neck cancer (HNC) survivors although few large studies report its prevalence and associated risk factors.

METHODS

A cross-sectional survey assessing demographic, behavioral, and clinical risk factors for NP. NP was assessed using the Self-administered Leeds Assessment of Neuropathic Symptoms and Signs pain scale (S-LANSS).

RESULTS

Forty-five percent (227/505) reported having pain including 13.7% (69/505) who were positive for S-LANSS. Reported pain sites were in the regions of the head and oral cavity (46.2%) and neck and throat (41.5%). Despite a higher self-reported use of analgesic medication (NP+ = 41.2%; NP- = 27.4%; p = 0.020) and alternative pain therapies (NP+ = 19.1%; NP- = 8.4%; p = 0.009), severe pain was more prevalent among those with NP (N+ = 23.2%; NP- = 13.3%; p = 0.004). Adjusted for opioid medications, ethnicity/race, age, surgery, depression, and comorbidities were risk factors for NP.

CONCLUSION

NP remains prevalent in HNC survivors highlighting the importance of routine pain surveillance.

From HDAC to Voltage-Gated Ion Channels: What's Next? The Long Road of Antiepileptic Drugs Repositioning in Cancer

Simple Summary

Although in the last decades the clinical outcome of cancer patients considerably improved, the major drawbacks still associated with chemotherapy are the unwanted side effects and the development of drug resistance. Therefore, a continuous effort in trying to discover new tumor markers, possibly of diagnostic, prognostic and therapeutic value, is being made. This review is aimed at highlighting the anti-tumor activity that several antiepileptic drugs (AEDs) exert in breast, prostate and other types of cancers, mainly focusing on their ability to block the voltage-gated Na⁺ and Ca⁺⁺ channels, as well as to inhibit the activity of histone deacetylases (HDACs), all well-documented tumor markers and/or molecular targets. The existence of additional AEDs molecular targets is highly suspected. Therefore, the repurposing of already available drugs as adjuvants in cancer treatment would have several advantages, such as reductions in dose-related toxicity CVs will be sent in a separate mail to the indicated address of combined treatments, lower production costs, and faster approval for clinical use.

Abstract

Cancer is a major health burden worldwide. Although the plethora of molecular targets identified in the last decades and the deriving developed treatments, which significantly improved patients’ outcome, the occurrence of resistance to therapies remains the major cause of relapse and mortality. Thus, efforts in identifying new markers to be exploited as molecular targets in cancer therapy are needed. This review will first give a glance on the diagnostic and therapeutic significance of histone deacetylase (HDAC) and voltage gated ion channels (VGICs) in cancer. Nevertheless, HDAC and VGICs have also been reported as molecular targets through which antiepileptic drugs (AEDs) seem to exert their anticancer activity. This should be claimed as a great advantage. Indeed, due to the slowness of drug approval procedures, the attempt to turn to off-label use of already approved medicines would be highly preferable. Therefore, an updated and accurate overview of both preclinical and clinical data of commonly prescribed AEDs (mainly valproic acid, lamotrigine, carbamazepine, phenytoin and gabapentin) in breast, prostate, brain and other cancers will follow. Finally, a glance at the emerging attempt to administer AEDs by means of opportunely designed drug delivery systems (DDSs), so to limit toxicity and improve bioavailability, is also given.

Radiotherapy for a Patient With Spinal Cord Stimulation: A Case Report

Cancer-related neuropathic pain is prevalent in up to 40% of patients with advanced disease. Spinal cord stimulation (SCS) is used to treat chronic pain when other treatments are ineffective. Radiotherapy is an established treatment modality for patients with oncological diseases. The ionizing radiation from radiotherapy can potentially damage electrical devices, including SCS devices. Additionally, all parts of SCS can potentially interfere with radiotherapy delivery. We present a case of successful administration of radiotherapy to a patient without damaging the SCS device implanted in proximity to the target lesion.

Comprehensive Targeted Treatment for Neuropathic and Nociceptive Pain in Palliative Care Patients

BACKGROUND

Pain is a common symptom in patients with advanced, metastatic, or terminal cancer. Neuropathic pain and psycho-emotional suffering are factors that increase the difficulty of pain management. Pain control in patients with cancer remains a challenge for medical professionals.

STUDY QUESTION

What is the evolution of neuropathic/mixed pain compared with nociceptive pain under standardized treatment in patients with cancer?

STUDY DESIGN

A prospective, longitudinal, open-label, nonrandomized study was conducted on patients with cancer pain.

MEASURES AND OUTCOMES

Pain type was assessed at admission using the modified Brief Pain Inventory, and pain intensity was assessed daily using the Numerical Rating Scale for 14 days and on days 21 and 28. Screening of depression was performed on days 1, 7, 14, 21, and 28 using the Hamilton Depression Rating Scale. Patients with pain and depression received analgesics with antidepressants, while patients without depression received analgesics or analgesics with an anticonvulsant depending on the pain subtype.

RESULTS

Of 72 patients, 23 had nociceptive pain and 49 had neuropathic/mixed pain. At admission, pain intensity was higher for patients with neuropathic/mixed pain compared with nociceptive pain (mean values: 7.06 vs. 5.82) with statistical significance (P = 0.001) and remained as such at the end of this study (mean values: 3.77 vs. 2.73). A decrease in the mean pain intensity was observed in all types of pain, but without statistical significance regardless of pain type and treatment protocol used (P = 0.77). If depression was present, antidepressants combined with analgesics decreased pain and depression scores significantly (P = 0.001).

CONCLUSIONS

Patients with neuropathic/mixed pain have higher levels of pain and lower response to treatment. Identifying psycho-emotional suffering can improve pain control by intervening in the physical and psycho-emotional components of pain.

Practical Considerations for the Use of Cannabis in Cancer Pain Management—What a Medical Oncologist Should Know

Pain is a highly debilitating emotional and sensory experience that significantly affects quality of life (QoL). Numerous chronic conditions, including cancer, are associated with chronic pain. In the setting of malignancy, pain can be a consequence of the tumor itself or of life-saving interventions, including surgery, chemotherapy, and radiotherapy. Despite significant pharmacological advances and awareness campaigns, pain remains undertreated in one-third of patients. To date, opioids have been the mainstay of cancer pain management. The problematic side effects and unsatisfactory pain relief of opioids have revived patients’ and physicians’ interest in finding new solutions, including cannabis and cannabinoids. The medical use of cannabis has been prohibited for decades, and it remains in Schedule 1 of the Misuse of Drugs Regulations. Currently, the legal context for its usage has become more permissive. Various preclinical and observational studies have aimed to prove that cannabinoids could be effective in cancer pain management. However, their clinical utility must be further supported by high-quality clinical trials.

Dexmedetomidine Continuous Infusion for Refractory Cancer Pain at End of Life: A Case Report

Refractory cancer-related pain at end-of-life (EoL) is multifaceted and may require utilizing medications with different mechanism of actions beyond opioids. We report the successful use of dexmedetomidine in a 63-year old female with recurrent breast cancer and intractable left arm pain and swelling admitted to University of California, San Diego, Health (UC San Diego Health), palliative care unit. Patient's pain and agitation continued to persist and she declined clinically despite efforts to start methadone, continuous infusion opioids, continuous infusion lidocaine and intravenous chlorpromazine by the palliative care team. On hospital day (HD) 11 patient was started on dexmedetomidine continuous infusion for refractory pain per our protocol at UC San Diego Health. The next day the patient appeared much improved in terms of pain and agitation with grimacing and moaning completely resolved. She was able to have some lucid periods and interacting with her family. With the addition of dexmedetomidine to her pain regiment, the patient was able to peacefully die 5 days later. This case report highlights the clinical utility of demedetomidine in a palliative care unit for refractory pain at EoL.

A Delphi Study on the Management of Neuropathic Cancer Pain in Spain: The DOLNEO Study

Purpose

The objectives of this project were to assess the current situation and management of cancer-related neuropathic pain (CRNP) in Spain and to provide specific recommendations for the assessment, diagnosis and treatment of CRNP using a Delphi methodology.

Methods

This was a qualitative study that followed a Delphi methodology using a questionnaire with 56 statements that were grouped into 5 areas related to CRNP: prevalence and impact, pathophysiology, assessment and diagnosis, specific syndromes, treatment, and multidisciplinary approach. Based on the responses, the scientific committee prepared an algorithm and a recommended pathway for the management of CRNP.

Results

Seventy-nine physicians attended the meeting and completed the questionnaire. Consensus was reached for all statements relating to the prevalence and impact of CRNP. However, the perceptions of specialists from palliative care of the frequency and impact of CRNP differed from those of other specialists. A high degree of consensus was reached for all statements concerning the assessment and diagnosis of CRNP. Regarding specific syndromes, the only statement with a lack of consensus was that on the frequency of NP in patients undergoing radiotherapy. There were some disagreements regarding the multidisciplinary approach and referral criteria for the management of NP.

Conclusion

Our results show a large degree of agreement on the assessment, diagnosis and treatment of cancer-related neuropathic pain among the specialists involved in its management. There were, however, some disagreements regarding the multidisciplinary approach and referral criteria for the management of neuropathic pain.

Cellular and Molecular Machinery of Neuropathic Pain: an Emerging Insight

Purpose of Review

Neuropathic pain (NP) has been ubiquitously characterized by lesion and its linked somatosensory system either the central nervous system (CNS) or peripheral nervous system (PNS) This PNS episode is the most prevalent site of NP origin and is found to be associated with afferent nerve fibers carrying pain signals from injured/trauma site to the CNS including the brain. Several kinds of pharmacotherapeutic drugs shuch as analgesics, anti-convulsants, and anti-depressants are being employed for the its possible interventions. The NP has been a great interest to follow different pathophysiological mechanisms which are often considered to correlate with the metabolic pathways and its mediated disease. There is paucity of knowledge to make such mechanism via NP.

Recent Finding

Most notably, recent pandemic outbreak of COVID-19 has also been reported in chronic pain mediated diabetes, inflammatory disorders, and cancers. There is an increasing incidence of NP and its complex mechanism has now led to identify the possible investigations of responsible genes and proteins via bioinformatics tools. The analysis might be more instrumental as collecting the genes from pain genetic database, analyzing the variants through differential gene expression (DEG) and constructing the protein–protein interaction (PPI) networks and thereby determining their upregulating and downregulating pathways.

Summary

This review sheds a bright light towards several mechanisms at both cellular and molecular level, correlation of NP-mediated disease mechanism and possible cell surface biomarkers (receptors), and identified genes could be more promising for their pharmacological targets.

A Comprehensive study of the Abdominal Ganglia Part 3: An overview of the most commonly observed ganglion patterns, with particular emphasis on inferior mesenteric and gonadal ganglia

INTRODUCTION

Chronic pain from untreatable abdominal cancers or pancreatitis can severely decrease an individual's quality of life due to accompanying neuropathic pain, the most difficult pain mechanism to treat. Current treatment modalities focus on peripheral block or neurolysis procedures of the sympathetic ganglia in an attempt to curb the pain and improve quality of life. Reports indicated that these treatments are ineffective with patients either experiencing no relief or return the pain in a few weeks. The aim of this study was to investigate the location, macro- and microscopic morphology and interconnections of the abdominal ganglia.

METHODS

The abdominal sympathetic ganglia of nine adult cadavers were investigated. The locations, morphology, interconnections and microscopic structure was studied in 108 potential abdominal ganglia. Particular emphasis was placed on direct interconnectivity between the ganglia and histological morphology.

RESULTS

A total of 100 ganglia were confirmed histologically to contain ganglion cells. The number and locations of most of the ganglia identified in our study does not correspond to that described by previous reports. Numerous interconnections between the different ganglia, as well as direct communications with the lumbar sympathetic chain ganglia were observed.

CONCLUSIONS

The interconnections and presence of ganglion cells the nerves connecting the ganglia lead to the belief that the system should be considered as a unit and that pain fibers may be transmitted via alternative previously undiscovered pathways. If the pain treatments are to be reassessed with this information in mind, we believe that greater success could be achieved. This article is protected by copyright. All rights reserved.

Effect of Transdermal Fentanyl Patch Combined with Enhanced Recovery after Surgery on the Curative Effect and Analgesic Effect of Liver Cancer

Its goal was to see how a transdermal fentanyl patch combined with accelerated recovery after surgery (ERAS) affected the treatment efficacy and analgesic effect of liver cancer, as well as to help patients with liver cancer choose the right analgesic treatment and nursing mode. 150 patients with liver cancer were divided into group A (transdermal fentanyl patch), group B (ERAS), and group C (transdermal fentanyl patch combined with ERAS). Patients in the three groups were compared in terms of pain, survival, psychological status, adverse responses, postoperative recovery, and patient satisfaction. The results showed that under different treatment and nursing methods, the number of patients with mild cancer pain in the three groups was increased, especially the number of patients with mild cancer pain in group C (P < 0.05). Besides, the quality of life score of patients in each group was decreased. Patients who received the combination analgesia had a significantly higher quality of life than those who received simply a transdermal fentanyl patch or ERAS (P < 0.05). The scores of both the Hamilton anxiety scale (HAMA) and Hamilton depression rating scale (HAMD) of patients with the combined analgesia were decreased signally (P < 0.05). There were few patients with combined analgesia who had adverse reactions (P < 0.05). After surgery, the time of the first anal exhaust, first defecation, and first ambulation in group C were shorter than those in the other two groups (P < 0.05). To summarize, combining the two techniques aided in the recovery of gastrointestinal function as well as the physical recovery of patients following surgery. Furthermore, combining the two approaches produced a clear analgesic impact, which could improve patients' quality of life while also having a favorable clinical adoption effect.

Overcoming clinical challenges of refractory neuropathic pain

INTRODUCTION

: Refractory neuropathic pain (ReNP), and its definition, is widely disputed amongst clinicians due in part to unclear categorical diagnosing guidelines, overall time duration of neuropathic pain, and the exhaustiveness of treatment options. Usually ReNP is defined as chronic, intractable, and unresponsive neuropathic pain that have otherwise been untreatable.

AREAS COVERED

: In this narrative review, we discuss and summarize the effectiveness of prospective ReNP research conducted over the past 10 years. This research looks at pharmacological and interventional therapies in clinical trial settings. The pharmacological therapies discussed include the use of adjuvant treatments to improve the safety and efficacy of conventional approaches. Different modalities of administration, such as injection therapy and intrathecal drug delivery systems, provide targeted drug delivery. Interventional therapies such as neuromodulation, pulse radiofrequency, and nerve lesioning are more invasive, however, they are increasingly utilized in the field, as reflected in ongoing clinical trials.

EXPERT OPINION

: Based on the current data from RCTs and systematic reviews, it is clear that single drug therapy cannot be effective and has significant limitations. Transitioning to interventional modalities that showed more promising results sooner rather than later may be even more cost-efficient than attempting different conservative treatments with a high failure rate.

Lucid Dreams Associated with Pregabalin: Implications for Clinical Practice

Here, we describe a case of a patient with multiple myeloma who reported symptoms of lucid dreams. This patient was taking methadone for neoplasm related pain. The patient was also taking pregabalin which was initially started at dosing of 50 mg taken orally three times a day. Five days after initiation of pregabalin, the dosing was increased to 100 mg taken orally three times daily. The patient developed lucid dreams during a hospital stay and methadone was initially thought to be the cause of her lucid dreams. Methadone dosing was decreased with no success, and her lucid dreams persisted. On the patient's thirteenth day of hospital admission, the pregabalin dose was decreased from 100 mg three times a day to 75 mg twice daily. Five days later, the pregabalin was decreased from 75 mg twice daily to 50 mg twice daily. Pregabalin was continued for five more days and then discontinued. Resolution of the lucid dreams occurred following discontinuation of pregabalin. To our knowledge, this is the first reported case of an association between pregabalin and lucid dreams. Given that pregabalin is a widely used medication, we found this case to be relevant to describe this unique presentation.

Non-pharmacological integrative therapies for chronic cancer pain

Objective

Chronic pain is one of the most detrimental symptoms exhibited by cancer patients, being an indication for opioid therapy in up to half of the patients’ receiving chemotherapy and in 90% of advanced cases. Various successful non-pharmacological integrative therapy options have been explored and implemented to improve the quality of life in these patients. This review aims to highlight the mechanisms implicated; assessment tools used for cancer pain and summarize current evidence on non-pharmacological approaches in the treatment of chronic cancer pain.

Data sources

A review of the literature was conducted using a combination of MeSH keywords including “Chronic cancer pain,” “Assessment,” “Non-pharmacological management,” and “Integrative therapy.”

Data summary

Data on the approach and assessment of chronic cancer pain as well as non-pharmacological integrative options have been displayed with the help of figures and tables. Of note, non-pharmacological integrative management was divided into three subcategories; physical therapy (involving exercise, acupuncture, massage, and transcutaneous electric nerve stimulation), psychosocial therapy (e.g. mindful practices, supportive therapy), and herbal supplementation.

Conclusions

The use of non-pharmacological integrative therapy in the management of chronic cancer pain has been grossly underestimated and must be considered before or as an adjuvant of other treatment regimens to ensure appropriate care.

Treatment of Neuropathic Pain Directly Due to Cancer: An Update

Simple Summary

This review discusses treatment approaches for providing pain relief to oncological patients affected by pain caused by nerve damage due to the tumor, also known as neuropathic cancer pain. Although being encountered often and causing a relevant burden to these patients, neuropathic cancer pain remains still difficult to diagnose and treat. Strong evidence about the best drugs to be used remain limited, as do therapeutic choices.

Abstract

Neuropathic pain can be defined as pain related to abnormal somatosensory processing in either the peripheral or central nervous system. In this review article, with neuropathic cancer pain (NCP), we refer to pain due to nervous tissue lesions caused by the tumor or its metastases. Nervous tissue damage is the cause of cancer pain in approximately 40% of those experiencing cancer pain. Recognizing a neuropathic pathophysiology in these cases may be difficult and requires specific criteria that are not homogenously applied in clinical practice. The management of this type of pain can be challenging, requiring the use of specific non-opioid adjuvant drugs. The majority of the criteria for NCP diagnosis and management have been based mainly on results from the noncancer population, risking the failure of addressing the specific needs of this population of patients. In this review, we summarize current management options available for NCP and provide some insights on new promising treatments.

Pain Prevalence During Cancer Treatment: A Systematic Review and Meta-Analysis

CONTEXT

Pain is one of the most complex and prevalent symptoms in the cancer population. Despite the protective role of acute cancer-related pain, it is also an important predictor for the likelihood of developing chronic pain after cancer treatment.

OBJECTIVES

Since the last systematic review on pain prevalence rates during cancer treatment dates already from 2016, the aim of the present systematic review was to provide an overview of pain prevalence rates during cancer treatment since this previous review.

METHODS

A systematic search of the literature, including studies between 2014 and 2020, was conducted using the databases Pubmed, Embase, Scopus, Web of Science and Cochrane. Studies reporting pain prevalence rates during or within three months after curative cancer treatment was included. Title/abstract and full-text was screened double-blinded, followed by independent evaluation of the risk of bias. All prevalence rates were pooled within meta-analyses and a meta-regression was performed to clarify the amount of heterogeneity.

RESULTS

Of the 9052 studies, 12 studies were included in the meta-analysis of which 10 included breast cancer and two lung cancer patients. The pooled pain prevalence rate was 40% (95%CI 0.29-0.51), with a heterogeneity of 96%. Out of the meta-regression, only the covariate "method of pain measurement" significantly clarified the heterogeneity (P < 0.05), resulting in a residual heterogeneity of 94.88%.

CONCLUSION

Five years after the last systematic review published on this topic, pain is still very prevalent during cancer treatment. However, the pain prevalence rates were also very heterogeneous. These two findings emphasize the need for further research on the development of adequate pain assessment and pain management approaches during cancer treatment.

Neurotropin alleviates rat osteocarcinoma pain via P2X3 receptor activation in the midbrain periaqueductal gray

OBJECTIVES

Clinically effective analgesia treatment for patients afflicted with osteocarcinoma lessens the intensity of pain. The midbrain periaqueductal gray (PAG) plays a critical role in pain modulation, and activation of P₂X₃ receptors in this region mediates pain processing. Neurotropin is a small molecule drug used for analgesic treatment of a number of chronic pain conditions. The present study aims at determining whether P₂X₃ receptor activation in PAG is responsible for the analgesic effect of neurotropin in rats with osteocarcinoma pain.

MATERIALS AND METHODS

The tibia of female Sprague-Dawley rats was inoculated with breast carcinoma cells to establish the osteocarcinoma pain model. The effects of intraperitoneal injection of 6, 12, and 18 neurotropin units (NU)/kg on pain threshold and receptor expression of P₂X₃ in the ventrolateral PAG (vlPAG) were assessed. The P₂X₃ receptor antagonist A-317491 (1.5 nmol/0.3 µl) was administered into vlPAG with a high-dose neurotropin (18 NU/kg) to determine the role of this receptor in the analgesic effect.

RESULTS

The pain thresholds of the rats with osteocarcinoma pain continuously decreased, whereas P₂X₃ receptor expression in vlPAG only slightly increased after osteocarcinoma cell inoculation. Neurotropin substantially elevated the pain threshold and P₂X₃ receptor expression in vlPAG in a dose-dependent manner. A-317491 microinjection into vlPAG significantly reduced the analgesic effects of neurotropin in the rats with osteocarcinoma pain.

CONCLUSION

Through these findings, it is shown that vlPAG P₂X₃ receptor activation participates in neurotropin-mediated analgesia mechanism in osteocarcinoma pain.

Chemotherapy-Induced Neuropathy and Diabetes: A Scoping Review

Although cancer and diabetes are common diseases, the relationship between diabetes, neuropathy and the risk of developing peripheral sensory neuropathy while or after receiving chemotherapy is uncertain. In this review, we highlight the effects of chemotherapy on the onset or progression of neuropathy in diabetic patients. We searched the literature in Medline and Scopus, covering all entries until 31 January 2021. The inclusion and exclusion criteria were: (1) original article (2) full text published in English or Spanish; (3) neuropathy was specifically assessed (4) the authors separately analyzed the outcomes in diabetic patients. A total of 259 papers were retrieved. Finally, eight articles fulfilled the criteria, and four more articles were retrieved from the references of the selected articles. The analysis of the studies covered the information about neuropathy recorded in 768 cancer patients with diabetes and 5247 control cases (non-diabetic patients). The drugs investigated are chemotherapy drugs with high potential to induce neuropathy, such as platinum derivatives and taxanes, which are currently the mainstay of treatment of various cancers. The predisposing effect of co-morbid diabetes on chemotherapy-induced peripheral neuropathy depends on the type of symptoms and drug used, but manifest at any drug regimen dosage, although greater neuropathic signs are also observed at higher dosages in diabetic patients. The deleterious effects of chemotherapy on diabetic patients seem to last longer, since peripheral neuropathy persisted in a higher proportion of diabetic patients than non-diabetic patients for up to two years after treatment. Future studies investigating the risk of developing peripheral neuropathy in cancer patients with comorbid diabetes need to consider the duration of diabetes, cancer-induced neuropathic effects per se (prior chemotherapy administration), and the effects of previous cancer management strategies such as radiotherapy and surgery.

Is Neuropathic Pain a Good Marker of Peripheral Neuropathy in Hospice Patients with Advanced Cancer? The Single Center Pilot Study

Neuropathic pain (NP) affects approximately 30% of patients with advanced cancer. The prevalence of neuropathic pain related to peripheral neuropathy (NP-RPN) in these patients is not known. The aim of the study was to evaluate NP-RPN prevalence in hospice patients and to find out whether the absence of this pain is sufficient to rule out peripheral neuropathy. The study included a total of 76 patients with advanced cancer who were cared for at inpatient hospices. All patients were asked about shooting or burning pain (of the feet and hands), were examined systematically for sensory deficits and had a nerve conduction study performed. NP-RPN was found in 29% of the patients. Electrophysiologically-diagnosed peripheral neuropathy was found in 79% of patients, and the diagnostic electrophysiological criteria for neuropathy were met by one half of the patients without NP-RPN. The severity of NP-RPN was correlated with the clinically assessed severity of sensory neuropathy and the Karnofsky score, but was not correlated with the intensity of the clinical signs of motor neuropathy. The presence of NP-RPN did not reflect greater prevalence of motor and sensory abnormalities in neurological and electrophysiological examinations. The absence of NP-RPN did not rule out polyneuropathy in hospice patients.

Co-Players in Chronic Pain: Neuroinflammation and the Tryptophan-Kynurenine Metabolic Pathway

Chronic pain is an unpleasant sensory and emotional experience that persists or recurs more than three months and may extend beyond the expected time of healing. Recently, nociplastic pain has been introduced as a descriptor of the mechanism of pain, which is due to the disturbance of neural processing without actual or potential tissue damage, appearing to replace a concept of psychogenic pain. An interdisciplinary task force of the International Association for the Study of Pain (IASP) compiled a systematic classification of clinical conditions associated with chronic pain, which was published in 2018 and will officially come into effect in 2022 in the 11th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-11) by the World Health Organization. ICD-11 offers the option for recording the presence of psychological or social factors in chronic pain; however, cognitive, emotional, and social dimensions in the pathogenesis of chronic pain are missing. Earlier pain disorder was defined as a condition with chronic pain associated with psychological factors, but it was replaced with somatic symptom disorder with predominant pain in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) in 2013. Recently clinical nosology is trending toward highlighting neurological pathology of chronic pain, discounting psychological or social factors in the pathogenesis of pain. This review article discusses components of the pain pathway, the component-based mechanisms of pain, central and peripheral sensitization, roles of chronic inflammation, and the involvement of tryptophan-kynurenine pathway metabolites, exploring the participation of psychosocial and behavioral factors in central sensitization of diseases progressing into the development of chronic pain, comorbid diseases that commonly present a symptom of chronic pain, and psychiatric disorders that manifest chronic pain without obvious actual or potential tissue damage.

Intravenous Ketamine for Cancer Pain Management, Including Flares During the COVID-19 Pandemic: A Retrospective Study

OBJECTIVES

Cancer-related neuropathic pain (CNP) affects an increasing proportion of cancer patients, given improved survival, but it remains difficult to treat. There are no studies on an extended intravenous ketamine protocol and its synergies with common neuropathy treatments to treat CNP. This study aims to 1) evaluate the safety and effectiveness of an intravenous ketamine protocol to treat refractory CNP and 2) uncover synergies between ketamine and common neuropathy treatments.

METHODS

This is a single-center, retrospective review of 57 patients and 192 infusions, with prospective follow-up on 14 enrolled patients during the coronavirus disease 2019 (COVID-19) pandemic.

RESULTS

The etiologies of CNP were as follows: 13 from tumor compression, 25 with chemotherapy-induced peripheral neuropathy, 13 from surgery, and 6 from radiation therapy. Overall, 42 of 57 patients (73.7%) were responders, and 71.8% of responders received >3 weeks of pain relief on their last infusion. Analysis of adjuvant treatments revealed that the combination of serotonin-norepinephrine reuptake inhibitors and ketamine resulted in an increase in responders compared with nonresponders (P < 0.01). Adverse events occurred in 32 of 192 infusions (16.7%). All side effects self-resolved or resolved with intervention per the adverse events protocol. During the pandemic, all 14 currently enrolled patients did not receive ketamine infusions. Thirteen of the 14 patients returned to baseline pain, with 61.5% increasing medications. All experienced worsened function, mobility, mood, or anorexia.

CONCLUSION

Intravenous ketamine may be a safe and effective adjuvant treatment for CNP, especially with serotonin-norepinephrine reuptake inhibitors. Larger, prospective studies are warranted and should explore parameters to help prognosticate response to ketamine infusions.

C-Reactive Protein and Its Relationship with Pain in Patients with Advanced Cancer Cachexia: Secondary Cross-Sectional Analysis of a Multicenter Prospective Cohort Study

Background: Limited information is available on the relationship between C-reactive protein (CRP) levels and pain in advanced cancer.

Objectives: To investigate the relationship between serum levels of CRP and subtypes of pain.

Design: A secondary cross-sectional analysis of a prospective cohort study.

Setting/Subjects: Patients with advanced cancer admitted to 23 palliative care units in Japan.

Measurements: Patients rated the severity of pain on the numerical rating scale (NRS) and physicians evaluated pain on the integrated palliative care outcome scale (IPOS). Physicians assessed neuropathic pain and breakthrough pain based on their presence or absence. Patients were divided into four groups according to CRP levels. Comparisons were performed using the Kruskal–Wallis test or chi-squared test. To evaluate the relationship between CRP and subtypes of pain, adjusted odds ratios (ORs) and 95% confidence intervals (CIs) in logistic models were calculated.

Results: We divided 1513 patients into four groups: low CRP (n = 234), moderate CRP (n = 513), high CRP (n = 352), and very high CRP (n = 414). Spearman's correlation coefficient between CRP and pain NRS and that between CRP and pain IPOS were 0.15 (p < 0.001) and 0.16 (p < 0.001), respectively. In the models of pain NRS and pain IPOS, significantly higher adjusted ORs than in the low CRP group were observed in the very high CRP group (1.81 [95% CI 1.14–2.88], p = 0.01; 1.74 [95% CI 1.18–2.57], p = 0.005, respectively). Relationships were not observed between CRP, neuropathic pain, and breakthrough pain.

Conclusions: The results indicated direct relationships between CRP, pain NRS, and pain IPOS.

Preliminary effects of low-intensity focused ultrasound treatment program for cancer-related neuropathic pain

Aim: To evaluate the effectiveness of low-intensity focused ultrasound (LIFU) therapy in the management of cancer-related neuropathic pain (CNP). Methods: A retrospective review with 22 patients with CNP treated with LIFU therapy (frequency 3 Hz, 3 W/cm², pulse mode duty cycle 50%) was conducted. Results: Out of the 22 patients, 15 had CNP secondary to chemotherapy-induced peripheral neuropathy. Compared with baseline, there was a significant reduction in numeric pain rating scale (p < 0.001). Additionally, 76.5% of patients (n = 13) were considered to be responders to LIFU therapy. Conclusion: LIFU therapy may be a viable treatment modality in the management of CNP, specifically chemotherapy-induced peripheral neuropathy, with a minimal side effect profile. Larger, prospective studies with a structured protocol are necessary.