The IASP classification of chronic pain for ICD-11: chronic cancer-related pain

Relationship between breakthrough cancer pain, background cancer pain and analgesic treatment - case series and review of the literature

The assessment and treatment of breakthrough cancer pain (BTcP) remain a major challenge in medicine due to its high impact on several aspects of health-related quality of life. BTcP should be carefully monitored in all cancer care settings by a multidisciplinary team to provide an appropriate and personalized clinical approach. The aim of this paper is to provide healthcare professionals involved in cancer pain management with a review of the relevant literature on the relationship between background cancer pain and BTcP which, by definition, occurs despite adequately controlled background cancer pain. The clinical cases presented contribute to a better understanding of this issue and underline its impact in daily clinical practice. This article is part of the Management of breakthrough cancer pain Special Issue: https://www.drugsincontext.com/special_issues/management-of-breakthrough-cancer-pain.

Chronic Pain in the ICD-11: New Diagnoses That Clinical Psychologists Should Know About

Background

In the 10th revision of the International Classification of Diseases and Related Health Problems (ICD-10), chronic pain was not represented adequately. Pain was left undefined and not recognized as a biopsychosocial phenomenon. Instead, a flawed dualism between psychological and somatic factors was implied. Individual diagnoses were ill-defined and scattered randomly through different chapters. Many patients received diagnoses in remainder categories devoid of meaningful clinical information.

Method

The International Association for the Study of Pain launched a Task Force to improve the diagnoses for the 11th revision of the ICD and this international expert team worked from 2013-2019 in cooperation with the WHO to develop a consensus based on available evidence and to improve the diagnoses.

Results

A new chapter on chronic pain was created with a biopsychosocial definition of pain. Chronic pain was operationalized as pain that persists or recurs longer than three months and subdivided into seven categories: Chronic primary pain and six types of chronic secondary pain. All diagnoses were based on explicit operationalized criteria. Optional extension codes allow coding pain-related parameters and the presence of psychosocial aspects together with each pain diagnosis.

Conclusion

First empirical studies demonstrated the integrity of the categories, the reliability, clinical utility, international applicability and superiority over the ICD-10. To improve reliability and ease of diagnosis, a classification algorithm is available. Clinical psychologists and other clinicians working with people with chronic pain should watch the national implementation strategies and advocate for multimodal and interdisciplinary treatments and adequate reimbursement for all providers involved.

Knowledge Mapping of International Research on Acupuncture for Chronic Pain: A Bibliometric Analysis

INTRODUCTION

With the wide acceptance of acupuncture, many papers and guidelines recommend that acupuncture is effective for chronic pain (CP). In this study, we applied bibliometric methods to analyze the current research situation of acupuncture intervention in CP, to gain insight into the current situation and future development trend of this field.

MATERIAL AND METHODS

Science Citation Index Expanded was searched for publications related to acupuncture for CP between 1900 and 2022. VOSviewer, CiteSpace and Thomson Data Analyzer were used to analyze the annual publication, authors and cited authors and their countries (regions) and institutions, journals and cited journals, cited references, co-occurrence keywords, burst keywords, and the relevant centrality.

RESULTS

A total of 1968 papers were retrieved, the annual publications have shown a rapid growth trend in the recent 20 years. The USA (708) and the Kyung Hee University (31) were the most productive country and institution, respectively, while the USA (0.37) and University of Maryland (0.13) had the highest centrality. MacPherson, Hugh published the most papers in this field (29), and Vickers, A J were the most influential author (289 times cited). Journal of Alternative and Complementary Medicine was the most productive journal (92), whereas PAIN was the most influential one (4743 times cited). Breivik, H's (2006) paper had the most citation count (3025), while Furlan's (2005) paper had the highest centrality (0.23). The research focuses in this field mainly include pain, electroacupuncture, Low back pain, Systematic review, Randomized controlled trial etc. Researchers are currently paying more attention to the psychological problems caused by CP.

CONCLUSION

The research of acupuncture for CP will be further expanded. International cooperation of this research field needs to be further strengthened. More high-quality designed trials need to be conducted.

Euphorbia tirucalli latex loaded polymer nanoparticles: Synthesis, characterization, in vitro release and in vivo antinociceptive action

The encapsulation of drugs in micro and nanocarriers has helped to resolve mechanisms of cellular resistance and decrease drug side effects as well. In this study, poly(D,L-lactide-co-glycolide) (PLGA) was used to encapsulate the Euphol active substance-containing latex from Euphorbia tirucalli (E-latex). The nanoparticles (NP) were prepared using the solvent evaporation method and the physical and chemical properties were evaluated using spectrophotometric techniques. FTIR was used to prove the formation of the ester bond between the E-latex and PLGA-NP. The UV-Vis spectroscopic technique was used to show that more than 75% of the latex was encapsulated; the same technique was used to determine the release profile of the compound at different pH values, as well as determining the speed with which the process occurs through kinetic models, and it was observed that the best adjustments occurred for the Korsmeyer-Peppas model and the Higuchi model. The DLS technique was used to determine the diameter of the particles produced as well as their zeta potential (ZP). The sizes of the particles varied from 497 to 764 nm, and it was observed that the increase in E-latex concentration causes a reduction in the diameter of the NP and an increase in the ZP (-1.44 to -22.7 mV), due to more functional groups from latex film being adsorbed to the NPs surfaces. The thermogravimetric experiments exhibit the glass transition temperatures (Tg) that is appropriate for the use of formulated NPs as a stable drug delivery device before use. The in vivo activity of E-NPs (30 and 100 mg/Kg/p.o.) was tested against carrageenan-induced mechanical hypernociception. The data demonstrated a significantly antinociceptive effect for E-NPs, suggesting that E-latex nanoencapsulation preserved its desired properties.

What is the relationship between physical activity and chronic pain in older adults? A systematic review and meta-analysis protocol

INTRODUCTION

Chronic pain is highly prevalent in older adults and can cause functional limitations, negatively affecting health and quality of life. Physical activity is a non-pharmacological approach used to prevent chronic pain as it promotes the release of endogenous opioids that block pain sensitivity. Therefore, we developed a systematic review protocol to analyse the relationship between physical activity and the occurrence and intensity of chronic pain in older adults.

METHODS AND ANALYSES

The systematic review will search PubMed, Scopus and Embase databases. The inclusion criteria will be observational studies that had primary chronic pain as an outcome, including persistent and intermittent pain. The population will include older adults from the community, living in a long-stay institution, or in outpatient follow-up. There will be no restriction regarding the year of publication and articles published in Portuguese, English and Spanish will be analysed. Effect or impact measures will be quantified, including OR, HR, prevalence ratio, incidence ratio and relative risk with their 95% CIs. If the data allow, a meta-analysis will be performed. The results may help understand the impact of physical activity as a potential protection factor against the occurrence of pain later in life as well as promote strategic prevention plans and public policies that encourage this practice in older adults.

ETHICS AND DISSEMINATION

Ethical approval is not required. The results will be disseminated via submission for publication to a peer-reviewed journal when complete.

PROSPERO REGISTRATION NUMBER

CRD42021282898.

Diagnosis, management and impact on patients' lives of cancer-related neuropathic pain (CRNP): A European survey

OBJECTIVE

This study assessed the impact of cancer-related neuropathic pain (CRNP) on patients and the importance of the patient-healthcare professional (HCP) relationship in diagnosis and management.

METHODS

A quantitative online survey was conducted involving adult patients from 13 European countries who had been diagnosed with treatable cancer and experienced symptoms of peripheral neuropathy.

RESULTS

Of 24,733 screened respondents, 549 eligible persons met the inclusion criteria and completed the questionnaire. Among individuals still experiencing pain, 75% rated it as 'severe' or 'moderate'. In addition, 61% reported a negative impact on day-to-day activities, and 30% said they had stopped working as a result. A third of respondents had received no diagnosis of CRNP despite reporting painful symptoms to an HCP. HCPs spending enough time discussing pain and understanding the impact on patients' lives were each associated with an increased likelihood of a formal CRNP diagnosis. Compared with individuals currently in active cancer treatment, cancer survivors were less likely to have a diagnosis of CRNP or regular pain conversations with HCPs.

CONCLUSION

CRNP remains under-recognised despite its substantial impact on patients' lives. Clinical practice may be improved by strengthening patient-HCP relationships around pain discussions and increasing the focus on pain management among cancer survivors.

Assessing pain after cancer treatment

OBJECTIVES

Chronic pain is common following cancer treatment. This is a brief discussion of pain assessment after cancer treatment.

METHODS

Summary of a lecure for the SASP (Scandinavian Journal of Pain) annual meeting 2022.

RESULTS

Assessment of pain involves identifying the presence of pain, its underlying cause, its impact as well as underlying mechanisms.

CONCLUSIONS

Detailed pain assessment is important for the clinic and for epidemiological and mechanistic studies as well as pain treatment studies.

Effectiveness of Virtual Reality-Based Interventions for Managing Chronic Pain on Pain Reduction, Anxiety, Depression and Mood: A Systematic Review

(1) Background: Patients diagnosed with chronic pain suffer from long-term pain, which negatively affects their daily lives and mental health. Virtual reality (VR) technologies are considered a therapeutic tool to manage pain perception and mental health conditions. This systematic review aimed to appraise the efficacy of VR in improving pain intensity, anxiety, depression and mood among patients with chronic pain; (2) Methods: Five electronic databases were systematically searched using the terms representing VR and chronic pain. Quality assessment was conducted using Cochrane Collaboration’s tool and Newcastle-Ottawa scale; (3) Results: Seventeen peer-reviewed articles were included in this review. It was found that VR was able to reduce pain intensity in patients with phantom limb pain, chronic headache, chronic neck pain and chronic low-back pain. The effects of VR on the improvement of anxiety, depression and mood were not determined due to the inadequate amount of clinical evidence; (4) Conclusions: VR, especially immersive VR, improves pain outcomes and its effects may vary depending on the approach and study design. More research is still needed to investigate the clinical use of VR in patients with chronic pain.

Non-steroidal anti-inflammatory drugs (NSAIDs) in cancer pain: A database analysis to determine recruitment feasibility for a clinical trial

BACKGROUND

Insufficient evidence exists to support or refute use of NSAIDs for managing cancer pain. Palliative physicians support a placebo-controlled trial of NSAIDs as strong opioid adjuncts for cancer-induced bone pain as the most pragmatic design to benefit clinical practice.

AIM

We aimed to determine patient numbers receiving palliative radiotherapy for cancer-induced bone pain, estimate the suitability of NSAID prescription and determine survival, guiding future trial feasibility.

DESIGN

A retrospective observational database analysis was undertaken using 5 years of routinely collected regional radiotherapy and healthcare data, filtered to achieve a cohort with cancer-induced bone pain. Demographics and survival were linked to available serology and co-morbidity data.

SETTING/PARTICIPANTS

Data was sourced from the regional Leeds Cancer Centre, a tertiary care setting. Patients who underwent palliative single fraction 8 gray (Gy) radiotherapy treatment for cancer-induced bone pain were included, totalling 2411 over 5 years.

RESULTS

A mean of 478 patients received palliative radiotherapy for cancer-induced bone pain annually. Median age (IQR) was 70 (62-77); negatively skewed (-0.69). 65.3% died within 1 year of radiotherapy; 48.0% within 6 months. Age was not associated with survival on univariable analysis (HR 0.999 (95% CI 0.996-1.003)). Serology from 1063 patients (44.2%) were available; eGFR was ⩾60 mL/min/1.73 m² in 83.0%. From available data (1352 pts; 51.6% of sample), 20.2% had a coded co-morbidity contra-indicating NSAIDs. Combining serology and co-morbidities, 68.5% could be considered for NSAID prescription.

CONCLUSIONS

Patient numbers at a regional radiotherapy centre support the feasibility of trial recruitment. Available serology and co-morbidity data suggest two-thirds may be suitable for NSAID prescription.

Cancer pain: Results of a prospective study on prognostic indicators of pain intensity including pain syndromes assessment

BACKGROUND

Pain is a prevalent symptom in patients with advanced cancer. Recognition of prognostic factors associated with pain intensity, could help provide better assessment, leading to better pain management.

AIM

identifying prognostic factors which could guide improvements on cancer pain classification.

DESIGN

a prospective observational study on chronic cancer pain, exploring the association between average mean pain intensity during a 28 days study follow-up and patients' clinical and pain-related characteristics, including pain syndromes. To evaluate these associations, a mixed model was built.

SETTING/PARTICIPANTS

Patients attending a Palliative Care and Pain Outpatient Clinic from May 2015 to June 2019 were screened. Patients with moderate to severe cancer pain who were already receiving or needed treatment with third step WHO ladder opioids were enrolled in the study. Data from 342 patients with at least one follow-up visit were analyzed.

RESULTS

Pain intensity decreased significantly for all patients during time (p < 0.001). Age, sex, emotional distress, pain duration and neuropathic pain presence evaluated by the Douleur Neuropathique 4 Questions (DN4) questionnaire were not significantly associated to pain intensity. Breakthrough/episodic pain was associated with higher pain intensity during follow-up (p < 0.001). The diagnosis of pain syndrome was overall significantly associated with mean pain intensity during follow-up (p = 0.016). Particularly, the concurrent presence of visceral and soft (p = 0.026) or soft and nervous tissue pain (p = 0.043) were significantly related to worse outcome, whereas pain due to only soft tissue damage with better outcome (p = 0.032).

CONCLUSIONS

The recognition of specific pain syndromes may help to better classify cancer pain.

Altered brain functional activity and connectivity in bone metastasis pain of lung cancer patients: A preliminary resting-state fMRI study

Bone metastasis pain (BMP) is one of the most prevalent symptoms among cancer survivors. The present study aims to explore the brain functional activity and connectivity patterns in BMP of lung cancer patients preliminarily. Thirty BMP patients and 33 healthy controls (HCs) matched for age and sex were recruited from inpatients and communities, respectively. All participants underwent fMRI data acquisition and pain assessment. Low-frequency fluctuations (ALFF) and regional homogeneity (ReHo) were applied to evaluate brain functional activity. Then, functional connectivity (FC) was calculated for the ALFF- and ReHo-identified seed brain regions. A two-sample t-test or Manny–Whitney U-test was applied to compare demographic and neuropsychological data as well as the neuroimaging indices according to the data distribution. A correlation analysis was conducted to explore the potential relationships between neuroimaging indices and pain intensity. Receiver operating characteristic curve analysis was applied to assess the classification performance of neuroimaging indices in discriminating individual subjects between the BMP patients and HCs. No significant intergroup differences in demographic and neuropsychological data were noted. BMP patients showed reduced ALFF and ReHo largely in the prefrontal cortex and increased ReHo in the bilateral thalamus and left fusiform gyrus. The lower FC was found within the prefrontal cortex. No significant correlation between the neuroimaging indices and pain intensity was observed. The neuroimaging indices showed satisfactory classification performance between the BMP patients and HCs, and the combined ALFF and ReHo showed a better accuracy rate (93.7%) than individual indices. In conclusion, altered brain functional activity and connectivity in the prefrontal cortex, fusiform gyrus, and thalamus may be associated with the neuropathology of BMP and may represent a potential biomarker for classifying BMP patients and healthy controls.

Profiles of adult people in a Spanish sample with chronic pain: Cluster analysis

AIM

To establish groups of people with chronic non-cancer pain according to the impairment caused by pain and to identify factors associated with the group with a higher level of impairment.

BACKGROUND

Knowing the profiles of people who suffer from chronic non-cancer pain could make it possible to direct their treatment and to detect associated risks.

DESIGN

A cross-sectional study.

METHODS

A sample of 395 people with chronic non-cancer pain was collected in Pain Units and Primary Healthcare Centres in southern Spain (January to March 2020). A cluster analysis was performed to divide the population into groups and a binary logistic regression model was established to determine factors associated with the group with a higher level of impairment.

RESULTS

Two groups were identified: lower level of impairment due to pain, characterized by being 45-65 years old, not medicated with opioids or anxiolytics, employed and with a mild level of impact on daily life; and higher level of impairment characterized by being older than 65 years old, medicated with opioids and anxiolytics, retired or on medical leave and with a severe impact on daily life. In addition, among women, being widowed, single or a smoker are risk factors for belonging to the group with a higher level of impairment; being smokers or consuming alcohol three or less times a week would be risk factors in men.

CONCLUSIONS

Age, chronic non-cancer pain impact on daily life, work situation and the consumption of opioid drugs and/or anxiolytics are factors that appear to influence the level of impairment due to chronic pain.

IMPACT

These findings could help detect impairment due to pain in its early stages, determining the specific needs of each person.

Upregulation of Spinal miR-155-5p Contributes to Mechanical Hyperalgesia by Promoting Inflammatory Activation of Microglia in Bone Cancer Pain Rats

Bone cancer pain (BCP) seriously deteriorates the life quality of patients, but its underlying mechanism is still unclear. Spinal microRNAs might contribute to the development of BCP and the role of microglial activation is controversial. In this study, we established a BCP model by injecting Walker 256 breast carcinoma cells into the tibial intramedullary cavity of rats and significant hyperalgesia was observed in the BCP rats. The lumbar spinal cords were harvested to perform RNA sequencing (RNA-seq), and 31 differentially expressed miRNAs (26 upregulated and 5 downregulated) were identified in the BCP rats. Among them, miR-155-5p was significantly upregulated in the BCP rats. Spinal microglial activation was observed during BCP development. miR-155-5p could be expressed in spinal microglia and was significantly upregulated in microglia treated with lipopolysaccharide (LPS) in vitro. Serum/glucocorticoid regulated kinase family member 3 (Sgk3) was predicted to be the possible downstream target of miR-155-5p and this was confirmed using a dual-luciferase reporter assay in vitro. The inhibition of miR-155-5p restored Sgk3-expression-attenuated microglial activation and alleviated hyperalgesia in the BCP rats. In conclusion, spinal miR-155-5p/Sgk3/microglial activation might play an important role in BCP pathogenesis.

Effect of Virtual Reality Hypnosis on Pain Threshold and Neurophysiological and Autonomic Biomarkers in Healthy Volunteers: Prospective Randomized Crossover Study

Background

Virtual reality hypnosis (VRH) is a promising tool to reduce pain. However, the benefits of VRH on pain perception and on the physiological expression of pain require further investigation.

Objective

In this study, we characterized the effects of VRH on the heat pain threshold among adult healthy volunteers while monitoring several physiological and autonomic functions.

Methods

Sixty healthy volunteers were prospectively included to receive nociceptive stimulations. The first set of thermal stimuli consisted of 20 stimulations at 60°C (duration 500 milliseconds) to trigger contact heat evoked potentials (CHEPs). The second set of thermal stimuli consisted of ramps (1°C/second) to determine the heat pain threshold of the participants. Electrocardiogram, skin conductance responses, respiration rate, as well as the analgesia nociception index were also recorded throughout the experiment.

Results

Data from 58 participants were analyzed. There was a small but significant increase in pain threshold in VRH (50.19°C, SD 1.98°C) compared to that in the control condition (mean 49.45°C, SD 1.87; P<.001, Wilcoxon matched-pairs signed-rank test; Cohen d=0.38). No significant effect of VRH on CHEPs and heart rate variability parameters was observed (all P>0.5; n=22 and n=52, respectively). During VRH, participants exhibited a clear reduction in their autonomic sympathetic tone, as shown by the lower number of nonspecific skin conductance peak responses (P<.001, two-way analysis of variance; n=39) and by an increase in the analgesia nociception index (P<.001, paired t-test; n=40).

Conclusions

The results obtained in this study support the idea that VRH administration is effective at increasing heat pain thresholds and impacts autonomic functions among healthy volunteers. As a nonpharmacological intervention, VRH has beneficial action on acute experimental heat pain. This beneficial action will need to be evaluated for the treatment of other types of pain, including chronic pain.

A Comprehensive Analysis of the Cancer Chronic Pain Experience: A Narrative Review

Cancer-related chronic pain (CP) represents a critical clinical issue through the disease, severely compromising the quality of life (QoL) of patients and the family environment. The current review employed a narrative method to synthesize the main results about the impact of cancer-related CP on QoL, adopting a multidimensional and threefold vision: patients, caregivers, and patient–caregiver perspective. Evidence emphasizes the importance of considering a bidirectional perspective (patient–caregiver) to understand better the pain experience throughout the cancer continuum and its consequences on QoL of patients and caregivers. Moreover, a holistic and multidimensional approach to cancer-related CP and its impact on QoL of patients and caregivers is still needed, in which the interconnection between physical, psychological, and social factors should be analyzed. Theoretical and methodological issues for orienting future social and family research initiatives were discussed.

Development and Validation of the Italian "Brief Five-Item Chronic Pain Questionnaire" for Epidemiological Studies

Background

Chronic pain (CP) prevalence estimates addressing a wide phenotype are still quite fragmented and may vary widely due to the lack of standardized tools of investigation. There is an urgent need to update general population CP estimates.

Methods

For this purpose, the Brief Five-item Chronic Pain Questionnaire was developed through experts' consultations for design and content validity assessment; literature analysis of measures used to investigate CP for general population surveys; understandability evaluation through a survey on a convenience sample of affected and non-affected individuals; reliability assessment by means of two double-wave online surveys carried out by the Italian Twin Registry; criterion and construct validity assessment through the third wave of the 2019 European Health Interview Survey (Ehis).

Results

Key dimensions were defined to describe CP main aspects from a public health perspective. Literature analysis showed that validated questionnaires were rarely used to address important public health CP aspects. Understandability of the measure was good. Test-retest analyses showed adequate reliability of the measure: k values were at least "moderate" with highest values regarding CP "occurrence" and "intensity". Correlations of CP with well-known comorbidities (cancer, depression), and specific traits (age, education) as well as of CP and its intensity with "physical pain occurrence and intensity" detected in the Ehis 2019, confirmed, respectively, a good construct and criterion validity. Construct validity was also evaluated through the correlation between "perceived treatment effectiveness" and "interference of pain in daily life activities" as recorded in the Ehis 2019.

Conclusion

The designed questionnaire is a brief self-administered measure, particularly suitable to detect persistent states of pain and related intensity in large-scale general population surveys by means of a first filtering item followed by four further items. It is, in fact, designed to detect CP possible underlying causes/triggers, drugs/treatments taking and frequency, and self-perceived effectiveness among CP sufferers. Further validation of the measure in different social and cultural contexts is desirable.

Potential Neuroimmune Interaction in Chronic Pain: A Review on Immune Cells in Peripheral and Central Sensitization

Chronic pain is a long-standing unpleasant sensory and emotional feeling that has a tremendous impact on the physiological functions of the body, manifesting itself as a dysfunction of the nervous system, which can occur with peripheral and central sensitization. Many recent studies have shown that a variety of common immune cells in the immune system are involved in chronic pain by acting on the peripheral or central nervous system, especially in the autoimmune diseases. This article reviews the mechanisms of regulation of the sensory nervous system by neutrophils, macrophages, mast cells, B cells, T cells, and central glial cells. In addition, we discuss in more detail the influence of each immune cell on the initiation, maintenance, and resolution of chronic pain. Neutrophils, macrophages, and mast cells as intrinsic immune cells can induce the transition from acute to chronic pain and its maintenance; B cells and T cells as adaptive immune cells are mainly involved in the initiation of chronic pain, and T cells also contribute to the resolution of it; the role of glial cells in the nervous system can be extended to the beginning and end of chronic pain. This article aims to promote the understanding of the neuroimmune mechanisms of chronic pain, and to provide new therapeutic ideas and strategies for the control of chronic pain at the immune cellular level.

Repetitive Transcranial Magnetic Stimulation of the Primary Motor Cortex beyond Motor Rehabilitation: A Review of the Current Evidence

Transcranial magnetic stimulation (TMS) has emerged as a novel technique to stimulate the human brain through the scalp. Over the years, identifying the optimal brain region and stimulation parameters has been a subject of debate in the literature on therapeutic uses of repetitive TMS (rTMS). Nevertheless, the primary motor cortex (M1) has been a conventional target for rTMS to treat motor symptoms, such as hemiplegia and spasticity, as it controls the voluntary movement of the body. However, with an expanding knowledge base of the M1 cortical and subcortical connections, M1-rTMS has shown a therapeutic efficacy that goes beyond the conventional motor rehabilitation to involve pain, headache, fatigue, dysphagia, speech and voice impairments, sleep disorders, cognitive dysfunction, disorders of consciousness, anxiety, depression, and bladder dysfunction. In this review, we summarize the latest evidence on using M1-rTMS to treat non-motor symptoms of diverse etiologies and discuss the potential mechanistic rationale behind the management of each of these symptoms.

Neuronal and non-neuronal TRPA1 as therapeutic targets for pain and headache relief

The transient receptor potential ankyrin 1 (TRPA1), a member of the TRP superfamily of channels, has a major role in different types of pain. TRPA1 is primarily localized to a subpopulation of primary sensory neurons of the trigeminal, vagal, and dorsal root ganglia. This subset of nociceptors produces and releases the neuropeptide substance P (SP) and calcitonin gene-related peptide (CGRP), which mediate neurogenic inflammation. TRPA1 is characterized by unique sensitivity for an unprecedented number of reactive byproducts of oxidative, nitrative, and carbonylic stress and to be activated by several chemically heterogenous, exogenous, and endogenous compounds. Recent preclinical evidence has revealed that expression of TRPA1 is not limited to neurons, but its functional role has been reported in central and peripheral glial cells. In particular, Schwann cell TRPA1 was recently implicated in sustaining mechanical and thermal (cold) hypersensitivity in mouse models of macrophage-dependent and macrophage-independent inflammatory, neuropathic, cancer, and migraine pain. Some analgesics and herbal medicines/natural products widely used for the acute treatment of pain and headache have shown some inhibitory action at TRPA1. A series of high affinity and selective TRPA1 antagonists have been developed and are currently being tested in phase I and phase II clinical trials for different diseases with a prominent pain component. Abbreviations: 4-HNE, 4-hydroxynonenal; ADH-2, alcohol dehydrogenase-2; AITC, allyl isothiocyanate; ANKTD, ankyrin-like protein with transmembrane domains protein 1; B2 receptor, bradykinin 2 receptor; CIPN, chemotherapeutic-induced peripheral neuropathy; CGRP, calcitonin gene related peptide; CRISPR, clustered regularly interspaced short palindromic repeats; CNS, central nervous system; COOH, carboxylic terminal; CpG, C-phosphate-G; DRG, dorsal root ganglia; EP, prostaglandins; GPCR, G-protein-coupled receptors; GTN, glyceryl trinitrate; MAPK, mitogen-activated protein kinase; M-CSF, macrophage-colony stimulating factor; NAPQI, N-Acetyl parabenzoquinone-imine; NGF, nerve growth factor; NH2, amino terminal; NKA, neurokinin A; NO, nitric oxide; NRS, numerical rating scale; PAR2, protease-activated receptor 2; PMA, periorbital mechanical allodynia; PLC, phospholipase C; PKC, protein kinase C; pSNL, partial sciatic nerve ligation; RCS, reactive carbonyl species; ROS, reactive oxygen species; RNS, nitrogen oxygen species; SP, substance P; TG, trigeminal ganglion; THC, Δ9-tetrahydrocannabinol; TrkA, neurotrophic receptor tyrosine kinase A; TRP, transient receptor potential; TRPC, TRP canonical; TRPM, TRP melastatin; TRPP, TRP polycystin; TRPM, TRP mucolipin; TRPA, TRP ankyrin; TRPV, TRP vanilloid; VG, vagal ganglion.

Chronic Cancer Pain: Opioids within Tumor Microenvironment Affect Neuroinflammation, Tumor and Pain Evolution

Pain can be a devastating experience for cancer patients, resulting in decreased quality of life. In the last two decades, immunological and pain research have demonstrated that pain persistence is primarily caused by neuroinflammation leading to central sensitization with brain neuroplastic alterations and changes in pain responsiveness (hyperalgesia, and pain behavior). Cancer pain is markedly affected by the tumor microenvironment (TME), a complex ecosystem consisting of different cell types (cancer cells, endothelial and stromal cells, leukocytes, fibroblasts and neurons) that release soluble mediators triggering neuroinflammation. The TME cellular components express opioid receptors (i.e., MOR) that upon engagement by endogenous or exogenous opioids such as morphine, initiate signaling events leading to neuroinflammation. MOR engagement does not only affect pain features and quality, but also influences directly and/or indirectly tumor growth and metastasis. The opioid effects on chronic cancer pain are also clinically characterized by altered opioid responsiveness (tolerance and hyperalgesia), a hallmark of the problematic long-term treatment of non-cancer pain. The significant progress made in understanding the immune-mediated development of chronic pain suggests its exploitation for novel alternative immunotherapeutic approaches.

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.

Effectiveness and Safety of Intrathecal Drug Delivery Systems for the Management of Cancer Pain: A Systematic Review and Meta-Analysis

OBJECTIVES

Intrathecal drug delivery systems (IDDS) and spinal cord stimulation (SCS) have been proposed and assessed for the management of cancer pain; however, such treatments remain underused. We conducted a systematic review to evaluate the effectiveness and safety of IDDS and SCS for cancer pain.

MATERIALS AND METHODS

Electronic databases MEDLINE, CENTRAL, EMBASE, and WikiStim were searched from 1988 to March 2021. Randomized controlled trials and observational studies of adults with pain related to cancer or its treatment who received an implantable IDDS or SCS were eligible for inclusion. The primary outcome of the review was change in pain intensity from baseline to the last available follow-up, measured using a visual analog scale or numerical rating scale. The protocol for this review is registered on PROSPERO (CRD42021240717).

RESULTS

A total of 22 studies (24 reports) included a total of 3043 participants who received either IDDS or SCS for cancer pain. Eight studies reporting data for 405 participants with an IDDS could be included in the meta-analysis of pain intensity that showed a statistically significant reduction at the latest posttreatment follow-up time compared with baseline (mean difference [MD], -3.31; 95% CI, -4.18 to -2.45; p < 0.001). Six studies reporting data for 325 participants with an IDDS could be included in the meta-analysis of pain intensity that showed a statistically significant reduction up to one month after treatment compared with baseline (MD, -3.53; 95% CI, -4.06 to -3.00; p < 0.001). A meta-analysis including studies of participants with either an IDDS or an SCS device showed similar results. Improvements in other outcomes following implantation of IDDS also were observed. Postdural puncture headache was the most reported complication, whereas urinary retention, nausea, and vomiting were commonly reported side effects.

CONCLUSION

Our findings suggest that IDDS is effective in reducing pain intensity for patients with cancer pain when compared with pretreatment.

Pain severity ratings in the 11th revision of the International Classification of Diseases: a versatile tool for rapid assessment

ABSTRACT

An improved classification of chronic pain is included in the 11th revision of the International Classification of Diseases (ICD-11). For all diagnoses of chronic pain, an optional dimensional code for the chronic pain severity will supplement the categorical diagnoses. Pain severity combines pain intensity, pain-related interference, and pain-related distress. Each component is rated by the patient on a numerical rating scale (NRS) from 0 to 10, and subsequently translated into severity stages ('mild'/'moderate'/'severe'). The present study aimed to evaluate this severity code by comparing the ratings with established psychometric measures of pain-related interference and distress. An online survey was posted to self-help groups for chronic pain, and 595 participants (88.7% women, 59.5±13.5 years) rated each of the severity parameters (pain intensity, pain-related interference, pain-related distress) on an NRS from 0 to 10 and completed the Pain Disability Index (PDI) and the Pain Coping Questionnaire (FESV, 3 subscales). The participants reported a mean pain intensity of 6.4±1.9, mean pain-related interference of 6.7±2.1, and mean pain-related distress of 5.7±2.5. The respective NRS ratings showed substantial correlations with the PDI score (r=.65) and the FESV subscales (r=.65, r=.56, r=.37). The extension code for pain severity is a valid and efficient way of recording additional dimensional pain parameters, which can be used to monitor the course of chronic pain and its treatment. The specifier's efficiency makes it possible to use the code when a questionnaire would not be feasible due to time constraints, such as in primary care.

Nonopioid drug combinations for cancer pain: a systematic review

Pain is highly prevalent in patients with cancer-nearly 40% report moderate-severe pain, which is commonly treated with opioids. Increasing cancer survivorship, opioid epidemics in some regions of the world, and limited opioid access in other regions have focused attention on nonopioid treatments. Given the limitations of monotherapy, combining nonopioids-such as antiepileptics and antidepressants-have shown promise in noncancer pain. This review seeks to evaluate efficacy of nonopioid combinations for cancer-related pain. Systematic searches of PubMed, EMBASE, and Cochrane CENTRAL were conducted for double-blind, randomized, controlled trials comparing a nonopioid combination with at least one of its components and/or placebo. This search yielded 4 randomized controlled trials, published between 1998 and 2019 involving studies of (1) imipramine + diclofenac; (2) mitoxantrone + prednisone + clodronate; (3) pentoxifylline + tocopherol + clodronate; and (4) duloxetine + pregabalin + opioid. In the first 3 of these trials, trends favouring combination efficacy failed to reach statistical significance. However, in the fourth trial, duloxetine + pregabalin + opioid was superior to pregabalin + opioid. This review illustrates recognition for the need to evaluate nonopioid drug combinations in cancer pain, although few trials have been published to date. Given the growing practice of prescribing more than 1 nonopioid for cancer pain and the need to expand the evidence base for rational combination therapy, more high-quality trials in this area are needed.

Pharmacologic Management of Persistent Pain in Cancer Survivors

Improvements in screening, diagnosis and treatment of cancer has seen cancer mortality substantially diminish in the past three decades. It is estimated there are almost 20 million cancer survivors in the USA alone, but some 40% live with chronic pain after completing treatment. While a broad definition of survivorship that includes all people living with, through and beyond a cancer diagnosis—including those with active cancer—is often used, this narrative review primarily focuses on the management of pain in people who are disease-free after completing primary cancer treatment as adults. Chronic pain in this population needs a different approach to that used for people with a limited prognosis. After describing the common chronic pain syndromes caused by cancer treatment, and the pathophysiologic mechanisms involved, the pharmacologic management of entities such as post-surgical pain, chemotherapy-induced neuropathy, aromatase inhibitor musculoskeletal syndrome and checkpoint inhibitor-related pain are described. The challenges  associated with opioid prescribing in this population are given special attention. Expert guidelines on pain management in cancer survivors now recommend a combination of pharmacologic and non-pharmacologic modalities, and these are also briefly covered.

Classification of chronic pain for the International Classification of Diseases (ICD-11): results of the 2017 international World Health Organization field testing

ABSTRACT

Because chronic pain has been poorly represented in the International Statistical Classification of Diseases and Related Health Problems (ICD) despite its significant contribution to the burden of disease worldwide, the International Association for the Study of Pain (IASP) developed a classification of chronic pain that was included in the ICD-11 version as "MG30" and approved by the World Health Assembly in 2019. The objective of this field test was to determine how well the classification of chronic pain works in the context of the ICD-11. A web-based survey using the WHO-FiT platform recruited 177 healthcare professionals from all WHO regions. After a training on coding chronic pain hosted by the IASP Web site, participants evaluated 18 diagnostic codes (lines) of the 2017 frozen version of the ICD-11 and 12 vignettes (cases) describing chronic pain conditions. Correctness, ambiguity, and perceived difficulty of the coding were compared between the ICD-11 and the ICD-10 and the applicability of the morbidity rules for the ICD-11 verified. In the line coding, 43.0% of correct chronic pain diagnoses assigned with the ICD-10 contrasted with 63.2% with the ICD-11. Especially in cases in which the chronic pain is regarded as the symptom of an underlying disease, the ICD-11 (63.5%) commanded more correct diagnoses than the ICD-10 (26.8%). The case coding was on average 83.9% accurate, only in 1.6% of cases any difficulty was perceived. The morbidity rules were applied correctly in 74.1% of cases. From a coding perspective, the ICD-11 is superior to the ICD-10 in every respect, offering better accuracy, difficulty, and ambiguity in coding chronic pain conditions.

Ketamine therapy for chronic pain in The Netherlands: a nationwide survey

OBJECTIVES

Ketamine is used to treat chronic refractory pain. However, there are no scientific guidelines for ketamine use in the Netherlands. The aim of this survey was to provide an overview of the use of ketamine for chronic pain in the Netherlands.

METHODS

All pain clinics in the Netherlands were contacted. A digital survey, available from June 2019 to January 2020, was sent to 68 pain clinics. The survey was completed by one pain physician as a representative of the entire pain department. The survey included questions about ketamine treatment indications, administration, dose, duration, treatment repetition and the inpatient or outpatient setting.

RESULTS

The survey was completed by 51 pain clinics (75.0%). Thirty-one clinics used ketamine for chronic pain treatment. The most common indication was Complex Regional Pain Syndrome (83.9%). Pain clinics administered ketamine via intravenous infusions (96.8%), iontophoresis (61.3%), subcutaneous (3.2%) or oral administration (3.2%). Intravenous ketamine treatment was offered in an inpatient setting in 14 pain clinics, in both an inpatient and outpatient setting in 11 pain clinics and in six pain clinics in an outpatient setting. In the outpatient setting, the median starting dose was 5 mg/h (IQR=17.5-5). The median maximum dose was 27.5 mg/h (IQR=100-11.9). The median infusion duration was 6 h (IQR=8-4). In the inpatient setting, the median starting dose was 5 mg/h (IQR=5-1.5) and the median maximum dose was 25 mg/h (IQR=25-14). Patients were admitted to hospital for a median of 4 days (IQR=5-1).

CONCLUSIONS

The results of this Dutch nationwide survey study show that there are heterogeneous treatment protocols with different indications, treatment setting and dosing regimen for the treatment of chronic pain with ketamine. This study encourages the formulation of a broader consensus and the development of evidence based guidelines for ketamine treatment.

Are mindfulness treatments effective for pain in cancer patients? A systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Mindfulness-based interventions (MBIs) have been recently applied in pain management and cancer care. However, inconsistencies exist concerning the effectiveness of MBIs on pain control among cancer patients. Therefore, this study aimed to examine the efficacy of MBIs on pain in cancer patients via a systematic review and meta-analysis of randomized controlled trials (RCTs).

METHODS

Databases (MEDLINE, PubMed, Embase, CINAHL, PsycINFO, Cochrane Central Register of Controlled Trials and ClinicalTrials.gov) were searched using key terms related to pain, cancer and mindfulness. The primary outcome was pain intensity. Standardized mean difference (SMD) of each outcome with 95% confidence interval (95% CI) was calculated. The quality of evidence was assessed by GRADE assessment.

RESULTS

Ten RCTs with 843 participants were included. Significant pooled effects of MBIs on pain intensity were found at both short-term (SMD = -0.19, 95% CI [-0.33 to -0.04]) and long-term (SMD = -0.20, 95% CI [-0.35 to -0.05]) follow-up, whereas no significance was observed for pain interference. In subgroup analyses, significant intervention effects were only seen in clinic-based MBIs compared to remote MBIs, and pooled effects of MBIs in attenuating pain were discovered relative to passive rather than active comparators. GRADE ratings showed moderate certainty of evidence in MBIs for pain intensity but low for pain interference.

CONCLUSIONS

The efficacy of MBIs in reducing pain intensity among cancer patients was revealed in this meta-analysis, albeit with a small effect size. Future research is warranted to optimize mindfulness treatment for pain control in cancer patients with high methodological quality and a large sample size.

SIGNIFICANCE

The effect of MBIs on pain in cancer patients was demonstrated in our analysis, albeit with small effect sizes. High-quality RCTs are needed to verify the efficacy of MBIs on cancer patients or survivors with pain complaints. Future trials should take into account the specific pain outcome measures (pain intensity or pain interference), the approach of intervention provision (clinic-based or remote MBI, group or individual practice), the duration and frequency of interventions and the comparators (passive or active control arms).

Lifestyle and Pain following Cancer: State-of-the-Art and Future Directions

This review discusses chronic pain, multiple modifiable lifestyle factors, such as stress, insomnia, diet, obesity, smoking, alcohol consumption and physical activity, and the relationship between these lifestyle factors and pain after cancer. Chronic pain is known to be a common consequence of cancer treatments, which considerably impacts cancer survivors' quality of life when it remains untreated. Improvements in lifestyle behaviour are known to reduce mortality, comorbid conditions (i.e., cardiovascular diseases, other cancer, and recurrence) and cancer-related side-effects (i.e., fatigue and psychological issues). An inadequate stress response plays an important role in dysregulating the body's autonomic, endocrine, and immune responses, creating a problematic back loop with pain. Next, given the high vulnerability of cancer survivors to insomnia, addressing and treating those sleep problems should be another target in pain management due to its capacity to increase hyperalgesia. Furthermore, adherence to a healthy diet holds great anti-inflammatory potential for relieving pain after cancer. Additionally, a healthy diet might go hand in hand with weight reduction in the case of obesity. Consuming alcohol and smoking have an acute analgesic effect in the short-term, with evidence lacking in the long-term. However, this acute effect is outweighed by other harms on cancer survivors' general health. Last, informing patients about the benefits of an active lifestyle and reducing a sedentary lifestyle after cancer treatment must be emphasised when considering the proven benefits of physical activity in this population. A multimodal approach addressing all relevant lifestyle factors together seems appropriate for managing comorbid conditions, side-effects, and chronic pain after cancer. Further research is needed to evaluate whether modifiable lifestyle factors have a beneficial influence on chronic pain among cancer survivors.

Roles of Long Non-coding RNAs in the Development of Chronic Pain

Chronic pain, a severe public health issue, affects the quality of life of patients and results in a major socioeconomic burden. Only limited drug treatments for chronic pain are available, and they have insufficient efficacy. Recent studies have found that the expression of long non-coding RNAs (lncRNAs) is dysregulated in various chronic pain models, including chronic neuropathic pain, chronic inflammatory pain, and chronic cancer-related pain. Studies have also explored the effect of these dysregulated lncRNAs on the activation of microRNAs, inflammatory cytokines, and so on. These mechanisms have been widely demonstrated to play a critical role in the development of chronic pain. The findings of these studies indicate the significant roles of dysregulated lncRNAs in chronic pain in the dorsal root ganglion and spinal cord, following peripheral or central nerve lesions. This review summarizes the mechanism underlying the abnormal expression of lncRNAs in the development of chronic pain induced by peripheral nerve injury, diabetic neuropathy, inflammatory response, trigeminal neuralgia, spinal cord injury, cancer metastasis, and other conditions. Understanding the effect of lncRNAs may provide a novel insight that targeting lncRNAs could be a potential candidate for therapeutic intervention in chronic pain.

The Needs and Experiences of Patients on Pain Education and the Clinical Reasoning of Physical Therapists Regarding Cancer-Related Pain. A Qualitative Study

Objective: This study offers direction for interaction between physical therapists and patients about cancer-related pain during physical training. The study may increase awareness of rehabilitation strategies for cancer-related pain during and after cancer treatment. Methods: Qualitative study, evaluating results of two qualitative studies. Data has been collected using semi-structured interviews, in which topics were discussed with patients and physical therapists. Respondents were adult patients with cancer in the Northern Netherlands with moderate to severe pain who followed physical training with a (oncologic) physical therapist. The physical therapists were respondents specialized in oncology and working with patients with cancer in a primary care setting in in the Netherlands. Data were analyzed using thematic analysis. Results: Eighteen patients and fifteen physical therapists were interviewed. Data was categorized in statements regarding "patients' needs", "patients' experiences" and "clinical reasoning of the physical therapist". "Patients' needs" for education were personal and included needs for information about the cause, course and effect of pain in relation to cancer and/or medical treatment, needs for practical tools for reducing pain, needs for strategies dealing with pain in daily activities, and needs for information about additional treatment and care options. When discussing 'patients' experiences', patients mentioned that physical therapists are cautious to express their expectations of the progress of pain and to offer pain education with respect to the cause of pain, dealing with pain and limitations in daily life, exercising, posture, learning self-care and information about additional treatment and care options in cancer-related pain. Patients provided insight into their educational, mental, and social support relative to experiences with physical therapists. Additionally, when discussing the communication they experienced with physical therapists, patients used descriptors such as accessibility, empathy, trust, knowledge and eliminating uncertainties. Interviews with physical therapists regarding their clinical reasoning process in cancer-related pain described that they identified pain from anamnesis (medical history review) and performed screening and analysis for pain secondary to cancer (treatment), as type of pain and pain influencing factors. Thoughts and experiences about pain, the use of pain clinometry, the establishment of objectives and interventions for physical therapy and multidisciplinary treatment of cancer-related pain were also described. Conclusion: Patients with cancer-related pain during physical training have personal needs regarding pain education and experience that specialized oncologic physical therapists focus on patient-centered information and self-management support. Specialized oncologic physical therapists analyze pain in the anamnesis and keep in mind the origin and impact of pain for the patient during screening and treatment. Different methods of pain management are used. It is recommended that physical therapists who give physical training take the initiative to repeatedly discuss pain.

Chronic pain in the 11th revision of the International Classification of Diseases: users' questions answered

ABSTRACT

The upcoming 11th revision of the International Classification of Diseases (ICD-11) will include a comprehensive classification of chronic pain for the first time, which is based on the biopsychosocial definition of chronic pain. This presents a great opportunity for pain research and clinical practice. The new classification consists of seven main diagnostic categories of chronic pain, which are further divided into increasingly specific levels of diagnoses. Each diagnosis is characterized by clearly defined operationalized criteria. Future users will need to familiarize themselves with the new system and its application. The aim of the present publication is to provide users of the ICD-11 chronic pain classification with answers to frequently asked questions regarding the ICD-11 as a whole, the ICD-11 chronic pain classification, and its application to common pain syndromes. The questions compiled here reached the International Association for the Study of Pain Task Force via different routes (e.g., at conferences, by letter, or during field testing). Furthermore, the authors collected questions posted to the ICD-11 browser and contacted early users of the classification to enquire about their most frequent difficulties when applying the new diagnoses. The authors of the present publication prepared answers to these frequently asked questions. This publication intends to act as a guide for the future users of the new ICD-11 chronic pain classification, hence facilitating its implementation.

Chronic pain, functionality and quality of life in cancer survivors

The increasing number of cancer survivors associated to a longer average life-span after diagnosis of an oncological disease facilitates the observation of deleterious long-term effects of both oncological disease and its treatment. Among these effects, chronic pain emerges as one of the most prevalent and, with its onset, there is a decrease in these patients' functionality and quality of life. The main focus in oncological disease treatment has been tumour eradication and average life expectancy extension after diagnosis, neglecting these deleterious long-term effects. This study aims at assessing the prevalence and characteristics of chronic pain in cancer survivors as well as pain interference in their quality of life and functionality. The study selected cancer survivors (n = 85) after dismissal from oncology service to assess the presence and characteristics of chronic pain, their health-related quality of life (HRQoL) and pain-related disability through a combination of different questionnaires. Chronic pain prevalence was 23.5%. In total, 85% of patients reported neuropathic pain descriptors and 45% presented diagnostic criteria for neuropathic pain. Of these patients, 45% were followed-up for pain surveillance and 35% underwent analgesic medication. There was a median pain disability index of 20.50 (14.50-35.00) and an average HRQoL of 0.5338 in chronic pain patients and 0.8872 in patients without pain. We found that chronic pain was the main negative predictor of HRQoL and was associated with decreased functionality. This study also concluded that these patients often were not offered the appropriate long-term medical follow-up. These findings highlight a need to raise awareness among health professionals to the importance of timely diagnosis and treatment of pain and its impact on HRQoL and functionality of long-term cancer survivors as well as the need to change clinical practice in order to improve healthcare provided to these patients.

[The management of multimorphic cancer pain, from diagnosis to treatment]

Cancer pain remains a major public health issue. Despite progress in pain medicine thanks to the interest shown in early and timely supportive care, more than half the patients managed for cancer are in pain. One of the key factors in high quality multidisciplinary management throughout the care pathway is to assess more than just pain: it is necessary to assess the patient as a whole. Understanding the complexity of cancer pain - or the various types of pain - through the innovative multimorphic cancer pain model, effectively opens up new perspectives for a targeted, personalised, and multimodal approach. The subsequent treatment strategies, whether drug-based with opioids, or interventional, are codified by guidelines based on scientific evidence for the healthcare professionals and, ultimately, patients.

The positive role of traditional Chinese medicine as an adjunctive therapy for cancer

Traditional Chinese medicine (TCM), especially Chinese herbal medicines and acupuncture, has been traditionally used to treat patients with cancers in China and other East Asian countries. Numerous studies have indicated that TCM not only alleviates the symptoms (e.g., fatigue, chronic pain, anorexia/cachexia, and insomnia) of patients with cancer and improves their quality of life (QOL) but also diminishes adverse reactions and complications caused by chemotherapy, radiotherapy, or targeted-therapy. Therefore, Chinese herbal medicines and acupuncture and other alternative therapies need to be understood by TCM physicians and other health care providers. This review mainly summarizes the experimental results and conclusions from literature published since 2010, and a search of the literature as been performed in the PubMed, MEDLINE, Web of Science, Scopus, Springer, ScienceDirect, and China Hospital Knowledge Database (CHKD) databases. Some Chinese herbal medicines (e.g., Panax ginseng, Panax quinquefolius, Astragali radix, Bu-zhong-yi-qi-tang (TJ-41), Liu-jun-zi-tang (TJ-43), Shi-quan-da-bu-tang (TJ-48), and Ban-xia-xie-xin-tang (TJ-14)) and some acupuncture points (e.g., Zusanli (ST36), Zhongwan (CV12), Neiguan (PC6) and Baihui (GV20)) that are commonly used to treat cancer-related symptoms and/or to reduce the toxicity of chemotherapy, radiotherapy, or targeted-therapy are highlighted and summarized. Through a review of literature, we conclude that TCM can effectively alleviate adverse gastrointestinal reactions (including diarrhea, nausea, and vomiting) to these anti-cancer therapies, decrease the incidence of bone marrow suppression, alleviate cardiotoxicity, and protect against chemotherapy-induced peripheral neuropathy and radiation-induced pneumonitis. Moreover, TCM can alleviate epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI)-related acneiform eruptions, diarrhea, and other adverse reactions. The hope is that this review can contribute to an understanding of TCM as an adjuvant therapy for cancer and that it can provide useful information for the development of more effective anti-cancer therapies. However, more rigorously designed trials involving cancer treatment must be conducted in the future, including complete quality control and standardized models at the cellular, organic, animal and clinical levels, in order to study TCM in multiple forms and at multiple levels.

Pain medication use for musculoskeletal pain among children and adolescents: a systematic review

OBJECTIVES

Musculoskeletal pain is common among children and adolescents. Despite the lack of evidence regarding harms and benefits, musculoskeletal pain is often managed with pain medication. The aim of this systematic review is to assess the prevalence of pain medication use for musculoskeletal pain among children and adolescents and the factors and side effects associated with use.

CONTENT

Three databases (EMBASE, CINAHL and PsychINFO) were systematically searched to identify studies designed to examine the prevalence, frequency or factors associated with the use of pain medication for musculoskeletal pain in children and adolescents (aged 6-19 years). The included studies were assessed for study quality and data were extracted.

SUMMARY

The search initially provided 20,135 studies. After screening titles, abstracts and full-texts, 20 studies were included. In school settings, 8-42% of children used pain medication for musculoskeletal pain, and 67-75% of children in sports clubs and from pain clinics used pain medication. The most consistent factors associated with the use of pain medications were pain characteristics and psychological factors (e.g. being bullied, low-self-esteem), while mixed evidence was found for increasing age and female gender. Only two studies reported on the duration of use and only one study on adverse effects related to the use of pain medication.

OUTLOOK

We found that 8-42% of adolescents from school-based samples use pain medication for MSK pain, while the prevalence among adolescents from sports clubs and pain clinics is higher (67-75%). Pain characteristics (pain duration, severity, intensity, disability levels and the presence of ≥2 pain conditions or multisite pain) and psychological factors were associated with a higher use of pain medication, while for higher age and female gender the evidence of association was mixed. Future studies should systematically collect information on the type, duration of use of pain medication and side effects to confirm the findings of this review.

Significance of descriptive symptoms and signs and clinical parameters as predictors of neuropathic cancer pain

Purpose

Evaluation of symptoms and signs for the management of neuropathic cancer pain (NCP) is challenging. This study aimed to identify clinical predictors of NCP and symptoms and signs most relevant of those in Korean patients.

Methods

This nationwide, descriptive, cross-sectional, multicenter, observational study included 2,003 cancer patients aged ≥20 years who reported a visual analog scale (VAS) score ≥1 for pain and provided informed consent for participation. The Douleur Neuropathic (DN4) questionnaire (score ≥4) was used to determine symptoms and signs as well as the presence of NCP.

Results

The prevalence of NCP was associated with age <65 years [OR, 1.57; 95% CI, 1.270–1.934], disease duration >6 months (OR, 1.57; 95% CI, 1.232–2.012), stage IV cancer (OR, 0.75; 95% CI, 0.593–0.955), history of chemotherapy (OR, 1.74; 95% CI, 1.225–2.472), and moderate-to-severe cancer pain (OR, 2.05; 95% CI, 1.671–2.524) after multivariate analysis. The most common descriptive symptoms of NCP were tingling, electric shock, and pins and needles. For NCP patients in the presence or absence of the clinical predictors, pins and needles (p = 0.001) and painful cold (p<0.001) symptoms were significantly frequent in patients with moderate-to-severe pain. Tingling, numbness, and touch hypoesthesia (p = 0.022, 0.033, 0.024, respectively) were more frequent in those with longer cancer duration and hyperesthesia (p = 0.024) was more frequent in young patients.

Conclusion

Age <65 years, disease duration >6 months, stage IV cancer, history of chemotherapy, and moderate-to-severe cancer pain, were identified as predictors of NCP. Some symptoms and signs of NCP were associated with these predictors. Further studies are warranted on the pathogenesis and management of NCP with respect to the symptoms and signs, and factors associated with pain severity in Korean patients.

Multidimensional Statistical Technique for Interpreting the Spontaneous Breakthrough Cancer Pain Phenomenon. A Secondary Analysis from the IOPS-MS Study

Breakthrough cancer pain (BTcP) is a temporary exacerbation of pain that "breaks through" a phase of adequate pain control by an opioid-based therapy. The non-predictable BTcP (NP-BTcP) is a subtype of BTcP that occurs in the absence of any specific activity. Since NP-BTcP has an important clinical impact, this analysis is aimed at characterizing the NP-BTcP phenomenon through a multidimensional statistical technique. This is a secondary analysis based on the Italian Oncologic Pain multiSetting-Multicentric Survey (IOPS-MS). A correlation analysis was performed to characterize the NP-BTcP profile about its intensity, number of episodes per day, and type. The multiple correspondence analysis (MCA) determined the identification of four groups (phenotypes). A univariate analysis was performed to assess differences between the four phenotypes and selected covariates. The four phenotypes represent the hierarchical classification according to the status of NP-BTcP: from the best (phenotype 1) to the worst (phenotype 4). The univariate analysis found a significant association between the onset time >10 min in the phenotype 1 (37.3%)' vs. the onset > 10 min in phenotype 4 (25.8%) (p < 0.001). Phenotype 1 was characterized by the gastrointestinal type of cancer (26.4%) with respect to phenotype 4, where the most frequent cancer affected the lung (28.8%) (p < 0.001). Phenotype 4 was mainly managed with rapid-onset opioids, while in phenotype 1, many patients were treated with oral, subcutaneous, or intravenous morphine (56.4% and 44.4%, respectively; p = 0.008). The ability to characterize NP-BTcP can offer enormous benefits for the management of this serious aspect of cancer pain. Although requiring validation, this strategy can provide many indications for identifying the diagnostic and therapeutic gaps in NP-BTcP management.

Breakthrough cancer pain in 2020

PURPOSE OF REVIEW

An overview on breakthrough cancer pain (BTCP), including inherent limitations of the terminology, assessment, clinical presentation, and treatment options.

RECENT FINDINGS

The estimated prevalence of BTCP is dependent on the defined cutoffs for controlled background pain and the magnitude of the pain flare. In addition, pain flares outside the definition of BTCP are prevalent. In the 11th Revision of the International Classification of Diseases, the temporal characteristics of cancer pain are described as continuous background pain and intermittent episodic pain. BTCP should be assessed by validated methods, and the patient perspective should be included. The pain may be related to neoplastic destruction of bone, viscera, or nerve tissue and is characterized by rapid onset, high intensity, and short duration. Treatment directed towards painful metastases must be considered. Due to pharmacological properties mirroring the pain characteristics, transmucosal fentanyl formulations are important for the treatment of BTCP. Oral immediate release opioids can be used for slow-onset or predictable BTCP. For more difficult pain conditions, parenteral, or even intrathecal pain medication, may be indicated.

SUMMARY

All clinically relevant episodic pains must be adequately treated in accordance with the patient's preferences. Transmucosal fentanyl formulations are effective for BTCP.

Prescriptions of analgesics during chronic cancer disease trajectories: A complete national cohort study

PURPOSE

Pain management principles vary considerably between chronic noncancer, acute and cancer pain. Cancer patients responding to oncological treatment may live with low tumor burden for years. Opioid treatment should reflect that the ratio between benefits and risks in these patients is different from patients with a rapidly progressive disease. Our study investigated the prescription patterns of analgesics in patients who died 6 to 9 years after cancer diagnosis.

PATIENTS AND METHODS

A pharmaco-epidemiological study based on the Norwegian Prescription Database and Cancer Registry of Norway. The 1-year periodic prevalence of receiving different analgesics and of persistent opioid use were analyzed. Persistent opioid use was defined as >365 Defined Daily Doses or >9000 mg Oral Morphine Equivalents during 365 days with prescriptions in all quarters of the 365 days period. Data were reported for the first 7 years for patients who lived 8-9 years after cancer diagnosis (N = 1502), while for patients who lived 6-7 years (N = 3817) data was reported for the first 5 years after diagnosis.

RESULTS

Compared to age- and gender adjusted general population, the 1-year periodic prevalence of opioid prescription was doubled the first year after diagnosis and remained raised with approximately 50%. The prevalence of persistent opioid use was threefold of the general population. Approximately 55% of patients with persistent opioid use 4 years after a cancer diagnosis were co-medicated with high doses of benzodiazepines and/or benzodiazepine-related hypnotics.

CONCLUSION

The findings of increased opioid use raise concerns regarding whether the benefits outweigh risks and side effects in this population.

Tetrodotoxin, a Potential Drug for Neuropathic and Cancer Pain Relief?

Tetrodotoxin (TTX) is a potent neurotoxin found mainly in puffer fish and other marine and terrestrial animals. TTX blocks voltage-gated sodium channels (VGSCs) which are typically classified as TTX-sensitive or TTX-resistant channels. VGSCs play a key role in pain signaling and some TTX-sensitive VGSCs are highly expressed by adult primary sensory neurons. During pathological pain conditions, such as neuropathic pain, upregulation of some TTX-sensitive VGSCs, including the massive re-expression of the embryonic VGSC subtype Na_V1.3 in adult primary sensory neurons, contribute to painful hypersensitization. In addition, people with loss-of-function mutations in the VGSC subtype Na_V1.7 present congenital insensitive to pain. TTX displays a prominent analgesic effect in several models of neuropathic pain in rodents. According to this promising preclinical evidence, TTX is currently under clinical development for chemo-therapy-induced neuropathic pain and cancer-related pain. This review focuses primarily on the preclinical and clinical evidence that support a potential analgesic role for TTX in these pain states. In addition, we also analyze the main toxic effects that this neurotoxin produces when it is administered at therapeutic doses, and the therapeutic potential to alleviate neuropathic pain of other natural toxins that selectively block TTX-sensitive VGSCs.

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.

Classification algorithm for the International Classification of Diseases-11 chronic pain classification: development and results from a preliminary pilot evaluation

ABSTRACT

The International Classification of Diseases-11 (ICD-11) chronic pain classification includes about 100 chronic pain diagnoses on different diagnostic levels. Each of these diagnoses requires specific operationalized diagnostic criteria to be present. The classification comprises more than 200 diagnostic criteria. The aim of the Classification Algorithm for Chronic Pain in ICD-11 (CAL-CP) is to facilitate the use of the classification by guiding users through these diagnostic criteria. The diagnostic criteria were ordered hierarchically and visualized in accordance with the standards defined by the Society for Medical Decision Making Committee on Standardization of Clinical Algorithms. The resulting linear decision tree underwent several rounds of iterative checks and feedback by its developers, as well as other pain experts. A preliminary pilot evaluation was conducted in the context of an ecological implementation field study of the classification itself. The resulting algorithm consists of a linear decision tree, an introduction form, and an appendix. The initial decision trunk can be used as a standalone algorithm in primary care. Each diagnostic criterion is represented in a decision box. The user needs to decide for each criterion whether it is present or not, and then follow the respective yes or no arrows to arrive at the corresponding ICD-11 diagnosis. The results of the pilot evaluation showed good clinical utility of the algorithm. The CAL-CP can contribute to reliable diagnoses by structuring a way through the classification and by increasing adherence to the criteria. Future studies need to evaluate its utility further and analyze its impact on the accuracy of the assigned diagnoses.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immune checkpoint inhibitor-related adverse events

Immune checkpoint inhibitors (ICIs) are the standard of care for the treatment of several cancers. While these immunotherapies have improved patient outcomes in many clinical settings, they bring accompanying risks of toxicity, specifically immune-related adverse events (irAEs). There is a need for clear, effective guidelines for the management of irAEs during ICI treatment, motivating the Society for Immunotherapy of Cancer (SITC) to convene an expert panel to develop a clinical practice guideline. The panel discussed the recognition and management of single and combination ICI irAEs and ultimately developed evidence- and consensus-based recommendations to assist medical professionals in clinical decision-making and to improve outcomes for patients.

Modulation of Pathological Pain by Epidermal Growth Factor Receptor

Chronic pain has been widely recognized as a major public health problem that impacts multiple aspects of patient quality of life. Unfortunately, chronic pain is often resistant to conventional analgesics, which are further limited by their various side effects. New therapeutic strategies and targets are needed to better serve the millions of people suffering from this devastating disease. To this end, recent clinical and preclinical studies have implicated the epidermal growth factor receptor signaling pathway in chronic pain states. EGFR is one of four members of the ErbB family of receptor tyrosine kinases that have key roles in development and the progression of many cancers. EGFR functions by activating many intracellular signaling pathways following binding of various ligands to the receptor. Several of these signaling pathways, such as phosphatidylinositol 3-kinase, are known mediators of pain. EGFR inhibitors are known for their use as cancer therapeutics but given recent evidence in pilot clinical and preclinical investigations, may have clinical use for treating chronic pain. Here, we review the clinical and preclinical evidence implicating EGFR in pathological pain states and provide an overview of EGFR signaling highlighting how EGFR and its ligands drive pain hypersensitivity and interact with important pain pathways such as the opioid system.

Chronic Opioid Therapy in Cancer Survivors at a Specialty Oncology Pain Clinic: Opioid Dosing, Efficacy, and Safety During Five Years of Pain Management

There are limited data regarding long-term safety and efficacy in cancer survivors receiving chronic opioid therapy. With conflicting recommendations on opioid-prescribing practices and lack of available outcome data, this study aimed to provide a longitudinal perspective on opioid prescribing in cancer survivors. A retrospective chart review at a comprehensive cancer care center pain clinic used data from pain clinic provider notes from 2013 to 2018. Inclusion criteria were patients in clinical remission not receiving active chemotherapy or immunotherapy and receiving opioids during the study period. Opioid dosing changes and outcomes between zero and five years were evaluated by standard statistical analysis. Thirty-two patients met inclusion criteria. Solid malignancies were more common than hematologic malignancies (72% vs. 28%). Common pain complaints were related to postsurgical changes (43%), postradiation (32%), and chemotherapy-induced pain syndromes (25%). There were no serious adverse events. One patient exhibited possible aberrant behavior. At the initial visit, the median morphine milligram equivalent per day (MME/day) was 130. Median MME/day at Year 0 (study start) and Year 5 was 135 and 159, respectively (P = 0.475). Functional status was satisfactory in 58% at Year 0 and increased to 91% of patients meeting their functional goals at Year 5. In a carefully monitored group of cancer survivors with persistent pain, chronic opioid therapy was safely managed during extended periods without significant opioid escalation or evidence of serious adverse events including aberrant behaviors. This population benefited when opioid therapy was managed with a focus on function rather than reduction of pain intensity scores.

[Pain management in cancer patients in a Tunisian hospital]

Pain is a common symptom in cancer patients. It is subjective and difficult to communicate. It continues to be outsourced and often overlooked despite the existence of multiple recommendations. The objective of this study is to describe pain management in cancer patients in a Tunisian hospital. This is a prospective study, conducted over one month at the maternity centre of Monastir by an intern in pharmacy using a questionnaire. Of 128 patients assessed, 50 were algic. Twenty-six percent of algic patients were not treated. The neuropathic component of pain was present in 30 % of cases but under treatment. Relief opioids were prescribed in 43 % of cases to relieve pain. Paracetamol was prescribed in 26 % of cases. Ten percent of patients use paracetamol self-medication. Sixteen percent of patients have tried non-pharmacological means, of which 62 % consume plants. To optimise the management of pain at our centre, the available analgesic sheets have been developed, validated by the medical staff and disseminated in the departments of carcinology and oncohematology. Therapeutic education sessions were also scheduled to warn patients about the risks of self-medication and misuse of medicinal plants. Pain management is complex. It requires respect for international recommendations, but especially for the efforts made by all stakeholders.

Neuropathic pain: clinical classification and assessment in patients with pain due to cancer

ABSTRACT

Neuropathic cancer pain (NcP) is associated with worse treatment responses and specific therapy indications, but a standardized clinical diagnosis of NcP is still lacking. This is a prospective observational study on outpatients with cancer, comparing different clinical approaches with NcP evaluation. A three-step assessment of NcP was performed using DN4 (cutoff of 4), palliative care physician Clinical Impression, including etiology and pain syndrome identification, and Retrospective Clinical Classification by a board of specialists with the IASP Neuropathic Pain Special Interest Group criteria. Neuropathic cancer pain classification was specifically referred to pain directly due to cancer. Three hundred fifty patients were assessed, and NcP prevalence was 20% (95% confidence interval [CI] 15.9%-24.6%), 36.9%, (95% CI 31.6%-42.1%), and 28.6% (95% CI 23.8%-33.9%) according to DN4, Clinical Impression, and Retrospective Clinical Classification, respectively. Cohen's kappa concordance coefficient between DN4 and Retrospective Clinical Classification was 0.57 (95% CI 0.47-0.67), indicating moderate concordance. Higher percentages of discordance were found for specific pain syndromes such as pain due to deep soft tissue infiltration and pain associated with tenesmus. Disagreement among clinicians accounted also for different NcP diagnoses and highlighted lack of homogeneous clinical criteria. Rigorous application of etiological and syndrome diagnosis to explain pain cause, associated with standardized diagnostic criteria and assessment of pain characteristics, that is also specific for the cancer pain condition could improve clinical classification of NcP.