Emerging factors in the progression of cancer-related pain

Virtual reality-guided mindfulness for chronic pain in cancer survivors: protocol for the virtual mind study-a single-group feasibility trial

Background

Chronic cancer-related pain (CRP) can have a significant negative impact on quality of life. Mindfulness is hypothesized to mitigate chronic CRP by regulating both physical and emotional resistance to pain. In recent years, there has been interest in the use of virtual reality (VR) to deliver mindfulness meditation. VR provides an immersive and engaging environment, which may enhance one's focused attention to present-moment experiences, potentially making mindfulness less effortful and more efficacious for individuals with chronic pain. There has been little research in this area for people with a history of cancer.

Objective

The aim of this mixed methods study is to evaluate the feasibility of a VR-guided mindfulness (VRGM) intervention offered to adult cancer survivors with chronic CRP.

Methods

This mixed methods feasibility study will employ a single-arm, pretest-posttest design with semistructured interviews. In total, 15 cancer survivors will be enrolled in a 6-week home-based intervention that consists of 10-15 min of daily VRGM practice. The primary outcome is feasibility as assessed by accrual rates, retention in the study, intervention adherence, questionnaire completion, and side effect rates. Participants will be assessed on psychosocial outcome measures (i.e., pain, sleep, depressive and anxiety symptoms, fatigue, quality of life, and mindfulness) before and after the intervention, and 6 weeks post intervention (follow-up). Changes in pain will be described in relation to levels of immersion and presence in the virtual environment, trait mindfulness, and amount of VRGM practice. Qualitative information will provide subjective detail on participants' experience with VRGM to complement quantitative data. This study has been approved by the Health Research Ethics Board of Alberta Cancer Committee (HREBA.CC-20-0411).

Conclusions

This novel intervention provides a potential alternative treatment to pharmacological pain management. Results from this study may inform future larger VGRM trials for chronic CRP to help reduce suffering in people with cancer. Study findings will be disseminated through open access publications, traditional conference presentations, professional cancer organizations, and social media platforms.

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.

Prevalence and associated factors of cancer pain among adult cancer patients evaluated at an oncology unit in the University of Gondar Comprehensive Specialized Hospital, northwest Ethiopia

Introduction

Globally, cancer is the second leading cause of death and was responsible for 9.6 million deaths in 2018. Worldwide, 2 million people experience pain every day, and cancer pain is one of the major neglected public health problems, especially in Ethiopia. Despite reporting the burden and risk factors of cancer pain as a principal importance, there are limited studies. Therefore, this study aimed to assess the prevalence of cancer pain and its associated factors among adult patients evaluated at the oncology ward in the University of Gondar Comprehensive Specialized Hospital, northwest Ethiopia.

Methods

An institution-based cross-sectional study was conducted from 1 January to 31 March 2021. A systematic random sampling technique was used to select the total sample size of 384 patients. Data were collected using pretested and structured interviewer-administered questionnaire. Bivariate and multivariate logistic regression models were fitted to identify the factors associated with cancer pain among patients with cancer. An adjusted odds ratio (AOR) with a 95% CI was computed to determine the level of significance.

Results

A total of 384 study participants were involved, with a response rate of 97.5%. The proportion of cancer pain was found to be 59.9% (95% CI 54.8-64.8). The odds of cancer pain were escalated by anxiety (AOR = 2.52, 95% CI 1.02-6.19), patients with hematological cancer (AOR = 4.68, 95% CI 1.30-16.74), gastrointestinal cancer (AOR = 5.15, 95% CI 1.45-18.2), and stages III and IV (AOR = 14.3, 95% CI 3.20-63.7).

Conclusion

The prevalence of cancer pain among adult patients with cancer in northwest Ethiopia is relatively high. Variables such as anxiety, types of cancer, and stage of cancer had a statistically significant association with cancer pain. Hence, to advance the management of pain, it is better to create more awareness regarding cancer-related pain and provide palliative care early on in the diagnosis of the disease.

Animal Models of Cancer-Related Pain: Current Perspectives in Translation

The incidence of pain in cancer patients during diagnosis and treatment is exceedingly high. Although advances in cancer detection and therapy have improved patient prognosis, cancer and its treatment-associated pain have gained clinical prominence. The biological mechanisms involved in cancer-related pain are multifactorial; different processes for pain may be responsible depending on the type and anatomic location of cancer. Animal models of cancer-related pain have provided mechanistic insights into the development and process of pain under a dynamic molecular environment. However, while cancer-evoked nociceptive responses in animals reflect some of the patients’ symptoms, the current models have failed to address the complexity of interactions within the natural disease state. Although there has been a recent convergence of the investigation of carcinogenesis and pain neurobiology, identification of new targets for novel therapies to treat cancer-related pain requires standardization of methodologies within the cancer pain field as well as across disciplines. Limited success of translation from preclinical studies to the clinic may be due to our poor understanding of the crosstalk between cancer cells and their microenvironment (e.g., sensory neurons, infiltrating immune cells, stromal cells etc.). This relatively new line of inquiry also highlights the broader limitations in translatability and interpretation of basic cancer pain research. The goal of this review is to summarize recent findings in cancer pain based on preclinical animal models, discuss the translational benefit of these discoveries, and propose considerations for future translational models of cancer pain.

Endothelin-1 enhances acid-sensing ion channel currents in rat primary sensory neurons

Endothelin-1 (ET-1), an endogenous vasoactive peptide, has been found to play an important role in peripheral pain signaling. Acid-sensing ion channels (ASICs) are key sensors for extracellular protons and contribute to pain caused by tissue acidosis. It remains unclear whether an interaction exists between ET-1 and ASICs in primary sensory neurons. In this study, we reported that ET-1 enhanced the activity of ASICs in rat dorsal root ganglia (DRG) neurons. In whole-cell voltage-clamp recording, ASIC currents were evoked by brief local application of pH 6.0 external solution in the presence of TRPV1 channel blocker AMG9810. Pre-application with ET-1 (1−100 nM) dose-dependently increased the proton-evoked ASIC currents with an EC₅₀ value of 7.42 ± 0.21 nM. Pre-application with ET-1 (30 nM) shifted the concentration–response curve of proton upwards with a maximal current response increase of 61.11% ± 4.33%. We showed that ET-1 enhanced ASIC currents through endothelin-A receptor (ET_AR), but not endothelin-B receptor (ET_BR) in both DRG neurons and CHO cells co-expressing ASIC3 and ET_AR. ET-1 enhancement was inhibited by blockade of G-protein or protein kinase C signaling. In current-clamp recording, pre-application with ET-1 (30 nM) significantly increased acid-evoked firing in rat DRG neurons. Finally, we showed that pharmacological blockade of ASICs by amiloride or APETx2 significantly alleviated ET-1-induced flinching and mechanical hyperalgesia in rats. These results suggest that ET-1 sensitizes ASICs in primary sensory neurons via ET_AR and PKC signaling pathway, which may contribute to peripheral ET-1-induced nociceptive behavior in rats.

Laser-photobiomodulation on experimental cancer pain model in Walker Tumor-256

CONTEXT

Cancer Pain is considered a common and significant clinical problem in malignant neoplasms, comprising 20% to 50% of all patients with tumor progression. Laser photobiomodulation (L-PBM) has been used in a multitude of pain events, ranging from acute trauma to chronic articular. However, L-PBM has never been tested in cancer pain.

OBJECTIVES

Evaluate hyperalgesia, edema, COX-1, COX-2, IL-10, and Bdkrb1 mRNA in low-level laser irradiated Walker-256 tumor-bearing rats.

METHODS

Rat hind paw injected with Walker Tumor-256 (W-256) and divided into six groups of 6 rats: G1 (control) - W-256 injected, G2- W-256 + Nimesulide, G3- W-256 + 1 J, G4- W-256 + 3 Jand G5- W256 + 6 J. Laser parameters: λ = 660 nm, 3.57 W/cm², Ø = 0.028 cm². Mechanical hyperalgesia was evaluated by Randall-Selitto test. Plethysmography measured edema; mRNA levels of COX-1, COX-2, IL-10, and Bdkrb1were analyzed.

RESULTS

It was found that the W-256 + 1 J group showed a decrease in paw edema, a significant reduction in pain threshold. Higher levels of IL-10 and lower levels of COX-2 and Bdkrb1 were observed.

CONCLUSION

Results suggest that 1 J L-PBM reduced the expression of COX-2 and Bdkrb1 and increasing IL-10 gene expression, promoting analgesia to close levels to nimesulide.

Interactions of peripheral endothelin-1 and nerve growth factor as contributors to persistent cutaneous pain

Endothelin-1 (ET-1) and Nerve Growth Factor (NGF) are proteins, released from cancer-ridden tissues, which cause spontaneous pain and hypersensitivity to noxious stimuli. Here we examined the electrophysiological and behavioral effects of these two agents for evidence of their interactions. Individual small-medium cultured DRG sensory neurons responded to both ET-1 (50 nM, n=6) and NGF (100 ng/ml, n=4), with increased numbers of action potentials and decreased slow K(+) currents; pre-exposure to ET-1 potentiated NGF´s actions, but not vice versa. Behaviorally, single intraplantar (i.pl.) injection of low doses of ET-1 (20 pmol) or NGF (100 ng), did not increase hindpaw tactile or thermal sensitivity, but their simultaneous injections sensitized the paw to both modalities. Daily i.pl. injections of low ET-1 doses in male rats caused tactile sensitization after 21 days, and enabled further tactile and thermal sensitization from low dose NGF, in ipsilateral and contralateral hindpaws. Single injections of 100 ng NGF, without changing the paw's tactile sensitivity by itself, acutely sensitized the ipsilateral paw to subsequent injections of low ET-1. The sensitization from repeated low ET-1 dosing and the cross-sensitization between NGF and ET-1 were both significantly greater in female than in male rats. These findings reveal a synergistic interaction between cutaneously administered low doses of NGF and ET-1, which could contribute to cancer-related pain.

Neurotrophin Receptors TrkA, p75NTR, and Sortilin Are Increased and Targetable in Thyroid Cancer

Neurotrophin receptors are emerging targets in oncology, but their clinicopathologic significance in thyroid cancer is unclear. In this study, the neurotrophin tyrosine receptor kinase TrkA (also called NTRK1), the common neurotrophin receptor p75^NTR, and the proneurotrophin receptor sortilin were analyzed with immunohistochemistry in a cohort of thyroid cancers (n = 128) and compared with adenomas and normal thyroid tissues (n = 62). TrkA was detected in 20% of thyroid cancers, compared with none of the benign samples (P = 0.0007). TrkA expression was independent of histologic subtypes but associated with lymph node metastasis (P = 0.0148), suggesting the involvement of TrkA in tumor invasiveness. Nerves in the tumor microenvironment were positive for TrkA. p75^NTR was overexpressed in anaplastic thyroid cancers compared with papillary and follicular subtypes (P < 0.0001). Sortilin was overexpressed in thyroid cancers compared with benign thyroid tissues (P < 0.0001). Neurotrophin receptor expression was confirmed in a panel of thyroid cancer cell lines at the mRNA and protein levels. Functional investigations using the anaplastic thyroid cancer cell line CAL-62 found that siRNA against TrkA, p75^NTR, and sortilin decreased cell survival and cell migration through decreased SRC and ERK activation. Together, these data reveal TrkA, p75^NTR, and sortilin as potential therapeutic targets in thyroid cancer.