Current Status of Malignant Neuropathic Pain in Chinese Patients with Cancer: Report of a Hospital-based Investigation of Prevalence, Etiology, Assessment, and Treatment

Assessment of neuropathic pain following cancer treatment

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

Patient Controlled Subcutaneous Analgesia of Hydromorphone Versus Morphine to Treat Moderate and Severe Cancer Pain: A Randomized Double-Blind Controlled Trial

CONTEXT

Hydromorphone and morphine are the common drugs used for the treatment of moderate to severe cancer pain. Patient controlled subcutaneous analgesia (PCSA) is an effective technique to manage cancer pain. However, few studies have been conducted to show the efficacy and safety of PCSA of hydromorphone for the relief of cancer pain.

OBJECTIVES

To explore the short-term efficacy and safety of PCSA elicited by hydromorphone for moderate to severe cancer pain.

METHODS

This was a single-center, randomized, active-controlled, double-blind trial (from April 2019 to August 2021). Sixty patients with moderate to severe cancer pain were randomized (1:1) to hydromorphone or morphine groups according to drug delivery by PCSA. The primary outcome was the pain intensity measured by a numerical rating scale (NRS) at 72 hours. Secondary outcomes included pain intensity measured by NRS at baseline, 15 minutes, 30 minutes, two hours, eight hours, 24 hours and 48 hours. The daily occurrence of breakthrough pain (BTP), impact of pain on quality of life measured by the brief pain inventory (BPI), the daily additional consumption of opioids and the incidence of adverse events were also recorded. Adverse events included nausea, vomiting, dizziness, constipation and respiratory depression.

RESULTS

A total of 57 patients (28 patients in the hydromorphone group and 29 patients in the morphine group) in the West China Hospital of Sichuan University were investigated. The mean (standard deviation [SD]) NRS in the two groups at baseline was 7.8 (1.7) in the hydromorphone group and 7.6 (1.7) in the morphine group, and at 72 hours were 3.4 (1.8) and 3.2 (1.5), respectively. The postoperative NRS in both groups was decreased significantly compared to baseline. The mean (SD) NRS at 30 minutes in the hydromorphone group was significantly lower than in the morphine group (3.9 [2.6] vs. 5.3 [2.1], P = 0.035). The daily occurrence of BTP in both groups at 48 hours and 72 hours decreased significantly compared to the corresponding baseline (P < 0.05), and there was no significant difference between the two groups. The total scores and sub-item scores of BPI at 24 hours and 72 hours after PCSA in both groups decreased significantly from baseline. A comparison of daily additional consumption of opioids between the two groups revealed no statistically significant difference. There were no significant differences in the incidences of nausea, vomiting, dizziness or constipation between the two groups (P > 0.05).

CONCLUSION

This study found that the PCSA of both hydromorphone and morphine could effectively and safely relieve short-term moderate to severe cancer pain. Of note, the PCSA of hydromorphone took effect more quickly than that of morphine.

Update on Prevalence of Pain in Patients with Cancer 2022: A Systematic Literature Review and Meta-Analysis

Experiencing pain and insufficient relief can be devastating and negatively affect a patient's quality of life. Developments in oncology such as new treatments and adjusted pain management guidelines may have influenced the prevalence of cancer pain and severity in patients. This review aims to provide an overview of the prevalence and severity of pain in cancer patients in the 2014-2021 literature period. A systematic literature search was performed using the databases PubMed, Embase, CINAHL, and Cochrane. Titles and abstracts were screened, and full texts were evaluated and assessed on methodological quality. A meta-analysis was performed on the pooled prevalence and severity rates. A meta-regression analysis was used to explore differences between treatment groups. We identified 10,637 studies, of which 444 studies were included. The overall prevalence of pain was 44.5%. Moderate to severe pain was experienced by 30.6% of the patients, a lower proportion compared to previous research. Pain experienced by cancer survivors was significantly lower compared to most treatment groups. Our results imply that both the prevalence of pain and pain severity declined in the past decade. Increased attention to the assessment and management of pain might have fostered the decline in the prevalence and severity of pain.

Neuropathic Pain: Biomolecular Intervention and Imaging via Targeting Microglia Activation

Many diseases, including cancer, can lead to neuropathic pain (NP). NP is one of the accompanying symptoms of suffering in many conditions and the life quality of NP patient is seriously affected. Due to complex causes, the effects of clinical treatments have been very unsatisfactory. Many experts have found that neuron-microglia interaction plays an essential role in NP occurrence and development. Therefore, the activation of microglia, related inflammatory mediators and molecular and cellular signaling pathways have become the focus of NP research. With the help of modern functional imaging technology, advanced pre-and clinical studies have been carried out and NP interventions have been attempted by using the different pharmaceuticals and the extracted active components of various traditional herbal medicines. In this communication, we review the mechanism of microglia on NP formation and treatment and molecular imaging technology's role in the clinical diagnosis and evaluation of NP therapies.

Effects of Pulsed Radiofrequency with Different Temperature on Model Rats of Chronic Constriction Injury

OBJECTIVES

The treatment for neuropathic pain is still a big challenge. Pulsed radiofrequency technique has been widely used to relieve neuropathic pain in recent years. The purpose of this study is to optimize the temperature for pulsed radiofrequency therapy.

DESIGN

Animal, experimental study.

METHODS

Seventy-five male SD rats were randomly divided into five groups: Sham operation group (Sham group), chronic constriction injury group (CCI group), PRF 42°C group (P42 group), PRF 50°C group (P50 group), and PRF 60°C group (P60 group). The hindpaw withdrawal threshold (HWT), paw thermal withdrawal latency (PTWL), sciatic nerve structure, and the concentration of spinal methionine enkephalin(M-ENK) were detected to identify which temperature is the best for PRF treatment.

RESULTS

PRF at 42°C, 50°C and 60°C significantly alleviated the pain in CCI rats. The therapeutic effects of 50°C and 60°C were similar, and both were better than 42°C. In addition, PRF using 42°C, 50°C, and 60°C mediated nerve injury to sciatic nerve were grade 1, 1, and 2, respectively. The concentration of M-ENK in spinal cord increased accompanying with the increasing of the temperature of PRF.

CONCLUSIONS

PRF using 50°C could induce less damage while achieving better improvement of mechanical and thermal pain threshold than 42°C and 60°C in CCI rats, which may be achieved by promoting the expression of M-ENK in spinal cord.

MiR-124-3p alleviates the dezocine tolerance against pain by regulating TRAF6 in a rat model

MicroRNAs (miRNAs) play important roles in drug tolerance and regulating pain. The purpose of the present study is to explore the regulatory mechanism of miR-124-3p on dezocine tolerance against pain in a rat model. The expression of miR-124-3p and TRAF6 in spinal cord of rats was detected by quantitative reverse-transcription PCR. The paw withdrawal latency (PWL) and maximal potential efficiency % of rats were detected by PWL assay. The levels of IL-1β and TNF-α in spinal cord tissues of rats were measured by ELISA assay. The interaction between TRAF6 and miR-124-3p was predicted by TargetScan software (http://www.targetscan.org) and confirmed by the dual-luciferase reporter assay. The protein level of TRAF6 was determined by western blot. MiR-124-3p expression was highly downregulated in a dezocine-resistant model. MiR-124-3p overexpression could alleviate dezocine tolerance in rats. TRAF6 expression was significantly upregulated in a dezocine-resistant model. MiR-124-3p targeted TRAF6 and TRAF6 was negatively modulated by miR-124-3p. In addition, overexpression of TRAF6 could reverse the inhibitory effects of miR-124-3p on dezocine tolerance. Overexpression of miR-124-3p alleviates dezocine tolerance against pain via regulating TRAF6 in a rat model, providing a possible solution to address dezocine tolerance in clinical.

Identification of neuropathic pain-associated genes and pathways via random walk with restart algorithm

BACKGROUND

Neuropathic pain (NP) develops from neuropathic lesions or diseases affecting the nervous system, and has become a serious public health issue due to its complex symptoms, high incidence and long duration. At present, the exact pathogenesis of NP is still unclear. In this study, we sought to identify the genes as well as the related molecular mechanisms associated with NP occurrence and development.

METHODS

We firstly identified the differentially expressed genes between NP spinal nerve ligation (SNL) rats and control sham rats and then projected them onto a STRING network for functional association analysis. Then, Random Walk with Restart (RWR) was conducted to find some new NP-related genes, with their potential functions sequentially analyzed by GO annotation and KEGG pathway analysis.

RESULTS

Some new NP-related genes, like Gng13, C3 and Cxcl2, were identified by RWR analysis. Meanwhile, some biological functions like inflammatory responses, chemotaxis and immune responses, as well as some signaling pathways, such as those involved in neuroactive ligand-receptor interactions, complement and blood coagulation cascade reactions, and cytokine-receptor interactions that the new NP- related genes were most activated were found to be associated with NP occurrence and development.

CONCLUSIONS

This study extends our knowledge of NP occurrence and development and provides new therapeutic targets for future NP treatment.

Computed tomography-guided paravertebral doxorubicin injection for refractory pain in patients with spinal metastases: Two case reports

RATIONALE

Diagnosing and treating refractory cancer pain have become standardized and effective procedures with guidance from the Expert Consensus on Refractory Cancer Pain released in 2017 by the Committee of Rehabilitation and Palliative Care of China. Doxorubicin has been used for perineural injection in the treatment of chronic non-cancer pain owing to its retrograde sensory ganglion resection effect. Our study reports a new fourth-ladder treatment for cancer pain: CT-guided paravertebral doxorubicin injection for patients with refractory cancer pain caused by paraspinal metastasis.

PATIENT CONCERNS

A 48-year-old female and a 47-year-old male patients suffered from refractory cancer pain over the past months. They had both undergone surgical tumor resection, chemotherapy, and precision radiotherapy but result in limited analgesic effect. The daily oral morphine dosage was around 60 to 100 mg and rescue analgesic methods had been used at the time.

DIAGNOSES

Refractory cancer pain in 2 patients with renal cancer and hepatobiliary adenocarcinoma.

INTERVENTIONS

The patients both received computed tomography (CT)-guided 1 mL of 0.5% doxorubicin paravertebral injection at each affected nerve root segments.

OUTCOMES

The Visual Analog Scale and Douleur Neuropathique four Questions were used for 6-month follow-up, and the analgesic requirement was also recorded. The patients enjoyed satisfactory analgesia for up to 6 months without adverse reaction. In addition, the oral opioid analgesic doses were significantly reduced after the neurolytic block.

LESSONS

The CT-guided paravertebral doxorubicin injection was an effective fourth-step analgesic interventional technology that allowed our 2 patients with refractory cancer pain to maintain satisfactory analgesia. This analgesia method taken at an appropriate stage, according to the latest analgesic concept, results in good analgesia and opioid use reduction. Also, with the imaging guidance, only a small amount of neurolytic agent is needed to achieve analgesia in a precise and safe way.

Cancer-Related Neuropathic Pain: Review and Selective Topics

Neuropathic pain is the result of neuroplastic and neuroinflammatory changes from trauma or diseases that damage the somatosensory system. Cancer-related neuropathic pain is caused by treatment, cancer, or paraneoplastic reactions to cancer. Approximately 30% of patients with cancer have neuropathic pain, mostly mixed nociceptive and neuropathic pain. History, physical examination, quantitative sensory testing, skin punch biopsies, and functional MRIs help to divide pain into phenotypes that may facilitate analgesic choices. Guidelines for treating cancer-related neuropathic pain are not consistent and are highly dependent on trials in patients without cancer. Combinations of analgesics are promising, whereas evidence for cannabinoids is meager.