Neuropathic pain in cancer patients: A brief review

Cellular and Molecular Machinery of Neuropathic Pain: an Emerging Insight

Purpose of Review

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

Recent Finding

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

Summary

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

The use of antineuropathic medications for the treatment of chronic pain

Chronic pain syndromes cost the US healthcare system over $600 billion per year. A subtype of chronic pain is neuropathic pain (NP), which is defined as "pain caused by a lesion or disease of the somatosensory system," according to the International Association for the Study of Pain (IASP). The pathophysiology of neuropathic pain is very complex, and more research needs to be done to find the exact mechanism. Patients that have preexisting conditions such as cancer and diabetes are at high-risk of developing NP. Many NP patients are misdiagnosed and receive delayed treatment due to a lack of a standardized classification system that allows clinicians to identify, understand, and utilize pain management in these patients. Medications like tricyclic antidepressants, serotonin-norepinephrine reuptake Inhibitor (SNRIs), and gabapentinoids are first-line treatments followed by opioids, cannabinoids, and other drugs. There are limited studies on the treatment of NP.

Differences in the Opioid Consumption of Terminally Ill Schizophrenic and Nonschizophrenic Cancer Patients: Analysis of Secondary National Population Data

CONTEXT

It is uncertain whether terminally ill schizophrenic cancer patients are hypoalgesic or have disparities in pain management.

OBJECTIVES

The objective of this study was to analyze the dosage of opioids used in terminally ill cancer patients with and without schizophrenia.

METHODS

This is a population-based retrospective cohort study based on data derived from the Taiwan National Health Insurance Research Database. Patients aged >20 years and newly diagnosed between 2000 and 2012 with at least one of the six most common cancers were included. After 1:4 matching, 1001 schizophrenic cancer patients comprised the schizophrenia cohort, while 4004 cancer patients without schizophrenia comprised the nonschizophrenia cohort. The percentage of opioid use, accumulated dose, and average daily dose near the end of life were analyzed for each cohort using multiple logistic and linear regression models.

RESULTS

The percentage of opioid use was lower in the schizophrenic cohort than the nonschizophrenic cohort during the last month before death (69.6% vs. 84.8%, odds ratio = 0.40, 95% CI = 0.34-0.48). The accumulated dose of opioid consumption was also lower in the schizophrenic cohort (2407 mg vs. 3694 mg, P value < 0.05).

CONCLUSION

Near the end of life, cancer patients with schizophrenia use less opioid than their nonschizophrenic counterparts. Cognitive impairment may be a cause in the disparity in end-of-life care for terminally ill schizophrenic cancer patients. Thus, we should formulate a more accurate pain scale system and pay attention to their need for pain treatment.

Home care with acupuncture increased the quality of life in a patient with advanced cancer with neuropathic pain induced by bone metastasis: a case report

A 66-year-old female patient was diagnosed with hepatocellular carcinoma accompanied by neuropathic pain induced by a metastatic tumor that compromised root and spinal canal. Although her pain was relieved following medical treatment, breakthrough pain occurring 1-2 times a day was still distressing. Neuropathic pain in her right lower limb caused discomfort and irritability and decreased her quality of life. We had limited options to adjust her prescription drug regime, due to the side effect of these drugs. Although acupuncture therapy was only performed at her home once a week, the efficacy was outstanding. The patient did not report any further instances of breakthrough pain, and she did not require additional bolus morphine. She could comfortably live in her familiar surroundings with her family and did not require any emergency room visits or admission into the hospital during the last month of her life. She had excellent quality of life in the terminal period of her life, and could even participate in a family function during this time. The present case report suggests that acupuncture may have a role in treating neuropathic pain induced by bone metastasis in patients with advanced cancer across clinical and in-home settings.

Integration of Specialized Pain Control Services in Palliative Care: A Nationwide Web-based Survey

Introduction:

Pain control is an important part of palliative care (PC), and conventional analgesics do not provide adequate pain relief to all patients. Many patients present with complex pain syndromes that require interventional pain control measures usually deployed by pain specialists. There is adequate integration of specialized pain control services with PC elsewhere, but information about the same in our country is lacking.

Materials and Methods:

An internet survey was conducted among palliative specialists regarding the need and availability of pain specialists for their patients suffering from complex pain syndromes. Their attitude toward integrating specialized pain control services in their practice was also explored.

Results:

Majority of palliative physicians came across situations where specialists in pain would control the patients’ pain better. There was a poor availability of such services, and when available, the cost was significant. It is heartening to note that though there is poor integration of specialized pain control services with palliation, palliative physicians acknowledge the need for pain specialists and their techniques for providing pain relief for their patients.

Conclusions:

Effective pain control is needed in palliation, barriers however exist, and there is a need to make pain specialists and interventional techniques more freely available.