Neurophysiology of cancer pain

Management of pain in colorectal cancer patients

In this review we focus on the pathophysiology of CRC-related pain and discuss currently applied pain management. Pain is a symptom reported by over 70 % of colorectal cancer (CRC) patients. It remains a feared and debilitating consequence of both cancer and cancer-related treatment. There are many options for pain management in CRC, consisting of intravenous, oral or topical medications. In order to address the full spectrum of pain, proper treatment should address the nociceptive, neuropathic and/or psychogenic pain component. Currently available methods do not bring pain relief to satisfying number of patients and, if used improperly, can cause a number of complications. Therefore, future treatments should focus primarily on alleviating pain, but also on reducing possible side effects. In this article we cover recent and promising pharmacological and non- pharmacological developments emerging in the field of CRC treatment.

Sarcopenia represents a negative prognostic factor in pancreatic cancer patients undergoing EUS celiac plexus neurolysis

Background and Objectives:

Increasing evidence suggests a prognostic role of sarcopenia in pancreatic cancer patients. The aim of this study was to assess the influence of sarcopenia on treatment outcomes after EUS-guided celiac plexus neurolysis (CPN).

Materials and Methods:

Data regarding 215 patients treated with EUS CPN between 2004 and 2019 were reviewed. Determination of body composition was conducted on contrast-enhanced CT scan, and pain response was considered as the primary outcome. Univariate and multivariate logistic regression was performed to identify the independent predictors of pain response.

Results:

Treatment was successful in 187 patients (86.9%). The median age was 62 (range 39–84) years, and most patients were male (61.8%). Of the whole study population, 139 patients (64.6%) were defined as sarcopenic, of which 116 (83.4%) responded to the treatment and 5 (3.5%) experienced a complete response. Among 76 nonsarcopenic participants, 71 (93.4%) responded to the treatment and 22 (28.9%) obtained a complete response (P = 0.03 and <0.001, respectively). The median duration of pain relief was 8 (2–10) and 15 (8–16) weeks in sarcopenic and nonsarcopenic patients, respectively (P = 0.01). The median overall survival after neurolysis was 4 months (3–5) in sarcopenic participants and 7 months (6–8) in nonsarcopenic participants (P = 0.05). Tumoral stage, interval from the diagnosis to treatment, and sarcopenia resulted as significant prognostic factors for treatment response both in univariate and multivariate regression analyses. No severe treatment-related adverse events were reported in the whole study population, with no difference between the two groups.

Conclusions:

Sarcopenia represents a predictor of poorer response to EUS CPN.

Analgesic efficacy of nefopam for cancer pain: a randomized controlled study

Background: Nefopam is a non-opioid, non-steroidal, central acting drug used effectively for postoperative pain. The efficacy of nefopam for cancer pain remains unclear. We aimed to evaluate the analgesic efficacy of nefopam for cancer pain in a randomized controlled trial. Methods: Patients with moderate to severe cancer pain (n=40) were randomly divided into two groups. The nefopam group (n=20) received three 20 mg doses of nefopam every 8 hours. The placebo group (n=20) received normal saline. Intravenous patient-controlled analgesia with morphine was given for breakthrough pain for 48 hours. The primary outcome was significant pain reduction. Secondary outcomes were morphine consumption over 48 hours and incidence of side effects. Results: The nefopam group showed pain reduction at 12 hours (65% of patients), 24 hours (80%), 36 hours (85%), and 48 hours (65%). The placebo group showed pain reduction at 12 hours (70%), 24 hours (75%), 36 hours (80%), and 48 hours (60%). However, there were no statistically significant differences between the groups (p>0.05). The median dosage of morphine consumption in 48 hours was lower in the nefopam group (25.5 mg) compared with the placebo group (37 mg), but this was not statistically significant (p=0.499). There were no statistically significant differences in blood pressure and heart rate between the groups. Side effects in both groups were comparable. Conclusions: At dosage of 60 mg in 24 hours, nefopam did not provide significant pain reduction in moderate to severe cancer pain patients. However, there was a trend of reduced opioid consumption. Further studies with larger sample sizes, longer duration, or higher doses of nefopam are warranted. Registration: Thai Clinical Trail Registry (TCTR) ID TCTR20181016001; registered on 12 October 2018.

Response to repeat echoendoscopic celiac plexus neurolysis in pancreatic cancer patients: A machine learning approach

BACKGROUND

/Objectives: Efficacy of repeat echoendoscopic celiac plexus neurolysis is still unclear. Aim of the study was to assess the efficacy of repeat celiac plexus neurolysis and to build an artificial neural network model able to predict pain response.

METHODS

Data regarding 156 patients treated with repeat celiac plexus neurolysis between 2004 and 2019 were reviewed. Artificial neural network and logistic regression models were built to predict pain response after treatment. Performance of the models was expressed in terms of accuracy, positive predictive value, and positive likelihood ratio.

RESULTS

Median age was 62 years (range 39-86) and most patients were male (66%) with pre-procedural visual analogue score 7. Fifty-one patients (32.6%) experienced treatment response, of which 6 (3.8%) complete pain suppression. Median duration of pain relief was 6 (2-8) weeks. Tumoral stage, interval from initial to repeat treatment, response to initial neurolysis, and tumor progression between the two treatments resulted as significant predictors of pain response. The performance of the artificial neural network in predicting treatment response was higher than regression model (area under the curve: 0.94, 0.89-0.97 versus 0.85, 0.78-0.89; p < 0.001). Positive predictive value and positive likelihood ratio resulted 90.3% and 19.35, respectively. Classification error rate was 5.7% with the artificial neural network compared to 14.7% of regression model (p < 0.001). These findings were confirmed through ten-fold cross validation.

CONCLUSIONS

Pain response following repeat neurolysis is generally less pronounced than after initial treatment. Artificial neural network may help to identify those subjects likely to benefit from repeat neurolysis.

Influence of Pain and Analgesia on Cancer Research Studies

Mice and rats are valuable and commonly used as models for the study of cancer. The models and methods of experimentation have the potential to cause pain to some degree, and all charged with ensuring animal welfare must determine how to manage it. A commonly posed question, especially from investigators and IACUC, is whether the provision of analgesic agents will render the model invalid. Left untreated, pain is a stressor and has negative consequences, most notably immune system perturbations. In addition, analgesic agents in the opioid and NSAID drug classes exhibit immunomodulatory activity and influence processes such as cell proliferation, apoptosis, and angiogenesis that are important in cancer formation. Therefore, both pain and the agents used to alleviate it have the potential to act as confounding factors in a study. This review article presents data from both human medicine and work with animal models in an attempt to help inform discussions about the withholding of analgesic agents from animals used in cancer studies.

Echoendoscopic ethanol ablation of tumor combined with celiac plexus neurolysis in patients with pancreatic adenocarcinoma

BACKGROUND AND AIM

Endoscopic ultrasonography guided-celiac plexus neurolysis relieves pain in patients with pancreatic cancer but with often suboptimal and transient results. The study aims to compare the efficacy and safety of endoscopic ultrasound-guided tumor ethanol ablation combined with celiac plexus neurolysis with respect to celiac plexus neurolysis alone for pain management in patients with pancreatic cancer.

METHODS

Among 123 patients with unresectable pancreatic cancer referred to our Institution between 2006 and 2014, 58 treated with endoscopic ultrasound-guided celiac plexus neurolysis (Group 1) and 65 with the combined approach (Group 2) were compared. Logistic regression models were applied to identify predictors of pain relief.

RESULTS

The two groups presented similar baseline clinical and tumoral parameters. Pre-procedural visual analog scale score was 7 in both groups (P = 0.8), and tumor max diameter was 38 mm (range 25-59) in Group 1 and 43 mm (22-59) in Group 2 (P = 0.4). The combined treatment increased pain relief and complete pain response rate (P = 0.005 and 0.003, respectively). Median duration of pain relief was 10 (7-14) and 18 (13-20) weeks in the two groups, respectively (P = 0.004). At multivariate regression, initial visual analog scale score and endoscopic technique adopted resulted significantly associated with pain relief. No severe treatment-related adverse events were reported. Median overall survival was 6.5 months (5.1-8.6) in Group 1 and 8.3 months (6-11.4) in Group 2 (P = 0.05).

CONCLUSIONS

Endoscopic ultrasound-guided tumor ablation combined with celiac plexus neurolysis appears to be superior to celiac plexus neurolysis alone in terms of pain control and overall survival.

Are newer, more expensive pharmacotherapy options associated with superior symptom control compared to less costly agents used in a collaborative practice setting?

Innovative approaches to care may be necessary to provide the most effective symptom management to hospice patients. One approach is prescribing newer pharmacotherapy options with the potential to improve symptom management in hospice. Such therapies are sometimes prescribed outside of Food and Drug Administration indications and are typically more costly than older agents usedfor the same symptoms. Another approach is the collaborative practice (CP) care model, whereby clinical pharmacists are given prescriptive authority according to evidence-based protocols and algorithms within boundaries approved by a physician. The agents typically included in CPprotocols are those with wide therapeutic indices and with substantial evidence to support their use. The purpose of this study was to examine both approaches to management ofpain, insomnia, and nausea, comparing symptom scores for those patients who received noncollaborative drug therapies (transdermal fentanyl, zolpidem, and ondansetron) to those who received agents under CP (oral sustained-release opioids, temazepam, andprochlorperazine). The object of the study was to investigate outcomes associated with newer drug therapy options as compared to older agents for the management of pain, insomnia, and nausea. A secondary goal is to compare symptom outcomes for patients receiving pharmaceutical care under CP and non-CP models. The study design was retrospective with a cohort. A total of 50 patients were randomly selected for each cohort of the pain and insomnia study arms. Only 45 patients prescribed oral ondansetron met inclusion criteriafor the nausea group; 45 patients prescribed prochlorperazine were randomly selected as the comparator group. Patients were compared on their degree of response to the prescribed therapy. Response was classified as complete, partial, no improvement from baseline, worsened, or unknown. A complete response was defined as the symptom score improving to a 0 of 10, regardless of the previous value documented. A partial response was defined as any improvement in score that did not result in a 0 of 10. No improvement from baseline reflected a lack of overall change in score throughout the series of data points collected. A worsened response was any score found to be higher than the score documented at the time of dispense. The unknown category reflects any set of scores that had an “NIA” documented at the time of medication dispense or when documented for both attempts subsequent to dispensing the medication. A complete response was present in 14 of 50 (24 percent) of the patients prescribed fentanyl as compared with 12 of 50 (28 percent) of those prescribed oral therapy (p = .82). Responses defined as partial, no improvement over baseline, worsened, and unknown were also comparable between the two cohorts. A complete response was seen in 26 patients prescribed temazepam (52 percent), whereas only 11 (22 percent) of patients initially prescribed zolpidem achieved the same response (p = .003 7). Both groups had a similar distribution of partial, no improvement over baseline, and worsened responses. For the nausea arm of the study, a difference was found in the number of complete responses, favoring prochlorperazine (22 of 45, 48.9 percent for prochlorperazine, 12 of 45, 26.7 percent for ondansetron, p =. 0504), as well as an increased number of worse responses seen with ondansetron patients (p = .0513); however, neither difference was statistically significant. Newer pharmacotherapy options for the management of pain, insomnia, and nausea were not found to be superior when compared to older agents prescribed under CR

A New Perspective of Neuromyopathy to Explain Intractable Pancreatic Cancer Pains; Dry Needling as an Effective Adjunct to Neurolytic Blocks

We present a new perspective of neuromyopathy in pancreatic cancer pain (PCP) referral to bodywall; proposal of new rationale to include ultrasound guided dry needling (USGDN) of body wall muscles as an effective adjunct to neurolytic coeliac plexus block (NCPB) or splanchnic nerve radiofrequency ablation (SRF) for comprehensive interventional management. Methods: PCP response to SRF in 2 patients and NCPB in 3 patients was documented on numerical rating scale (NRS) on post procedure days 3 and 15. If the residual pain was >5 NRS on day 15, USGDN of abdominal and back muscles was started on a thrice weekly basis. The response to USGDN documented on day 30 after approximately 6 sessions of DN, showed a significant pain reduction (0-2 NRS) with 50% reduction of pre-treatment opioid consumption. This was sustained at 6 months or till their demise. Convergence of visceral and somatic nerves at the dorsal horn (viscerosomatic neurons) causes referral of visceral pain to the back and abdominal muscles. This leads to formation of myofascial trigger points (MTrPs) in the muscles which sets up a parallel network of sensitized peripheral and central motor nociceptive processing (neuromyopathy). USGDN specifically addressed the MTrPs that develop as an epiphenomenon of self-perpetuating neuromyopathy while SRF/NCPB, analgesics and neuromodulators could address only visceral nociceptive afferents (pain mediated through celiac plexus) which forms a meagre 10% of the total spinal cord afferent input. Thus, we conclude that combination of neuromyopathy and viscerosomatic convergence in PCP indicate a specific role for DN as an adjunct to SRF/NCPB in our patients

Quercetin reduces Ehrlich tumor-induced cancer pain in mice

Cancer pain directly affects the patient's quality of life. We have previously demonstrated that the subcutaneous administration of the mammary adenocarcinoma known as Ehrlich tumor induces pain in mice. Several studies have shown that the flavonoid quercetin presents important biological effects, including anti-inflammatory, antioxidant, analgesic, and antitumor activity. Therefore, the analgesic effect and mechanisms of quercetin were evaluated in Ehrlich tumor-induced cancer pain in mice. Intraperitoneal (i.p.) treatments with quercetin reduced Ehrlich tumor-induced mechanical and thermal hyperalgesia, but not paw thickness or histological alterations, indicating an analgesic effect without affecting tumor growth. Regarding the analgesic mechanisms of quercetin, it inhibited the production of hyperalgesic cytokines IL-1β and TNFα and decreased neutrophil recruitment (myeloperoxidase activity) and oxidative stress. Naloxone (opioid receptor antagonist) inhibited quercetin analgesia without interfering with neutrophil recruitment, cytokine production, and oxidative stress. Importantly, cotreatment with morphine and quercetin at doses that were ineffective as single treatment reduced the nociceptive responses. Concluding, quercetin reduces the Ehrlich tumor-induced cancer pain by reducing the production of hyperalgesic cytokines, neutrophil recruitment, and oxidative stress as well as by activating an opioid-dependent analgesic pathway and potentiation of morphine analgesia. Thus, quercetin treatment seems a suitable therapeutic approach for cancer pain that merits further investigation.

Common biological pathways underlying the psychoneurological symptom cluster in cancer patients

BACKGROUND

A symptom cluster is a group of symptoms that occur together and are interrelated. The clinical implication of symptom cluster research is to use the clustering patterns of symptoms to understand the mechanisms for these symptoms and develop management strategies targeted at multiple symptoms.

OBJECTIVE

The purposes of this review were to summarize the evidence for a psychoneurological symptom cluster in cancer patients, to provide information regarding the underlying biological mechanisms for each of the psychoneurological symptoms within the cluster, and to propose possible common biological pathways that may underlie this cluster.

METHODS

A systematic review of the literature was conducted.

RESULTS

Empirical evidence exists to support a cluster of psychoneurological symptoms (ie, depressive symptoms, cognitive disturbance, fatigue, sleep disturbance, pain). At a molecular level, common biological pathways (ie, proinflammatory cytokines, hypothalamic-pituitary-adrenal axis, and monoamine neurotransmission system) may underlie the development of symptoms within this cluster. Activation of proinflammatory cytokines is proposed as a first stage of mechanistic pathway. However, other biological factors, such as lowered estrogen or hemoglobin levels, may influence psychoneurological cluster.

CONCLUSION

Additional studies are needed to confirm the roles of cytokines as well as other biological factors in the development of the psychoneurological cluster and to determine the biomarkers to identify the subgroups of cancer patients who are at greatest risk for this cluster.

IMPLICATIONS FOR PRACTICE

This information can be used by researchers and clinicians to guide the selection of symptom management strategies that are ideally targeted to the biological mechanisms that underlie this symptom cluster.

The effect of electroacupuncture on osteosarcoma tumor growth and metastasis: analysis of different treatment regimens

Osteosarcoma is the most common malignant bone tumor found in children and adolescents and is associated with many complications including cancer pain and metastasis. While cancer patients often seek complementary and alternative medicine (CAM) approaches to treat cancer pain and fatigue or the side effects of chemotherapy and treatment, there is little known about the effect of acupuncture treatment on tumor growth and metastasis. Here we evaluate the effects of six different electroacupuncture (EA) regimens on osteosarcoma tumor growth and metastasis in both male and female mice. The most significant positive effects were observed when EA was applied to the ST-36 acupoint twice weekly (EA-2X/3) beginning at postimplantation day 3 (PID 3). Twice weekly treatment produced robust reductions in tumor growth. Conversely, when EA was applied twice weekly (EA-2X/7), starting at PID 7, there was a significant increase in tumor growth. We further demonstrate that EA-2X/3 treatment elicits significant reductions in tumor lymphatics, vasculature, and innervation. Lastly, EA-2X/3 treatment produced a marked reduction in pulmonary metastasis, thus providing evidence for EA's potential antimetastatic capabilities. Collectively, EA-2X/3 treatment was found to reduce both bone tumor growth and lung metastasis, which may be mediated in part through reductions in tumor-associated vasculature, lymphatics, and innervation.

Optimal patient education for cancer pain: a systematic review and theory-based meta-analysis

PURPOSE

Previous systematic reviews have found patient education to be moderately efficacious in decreasing the intensity of cancer pain, but variation in results warrants analysis aimed at identifying which strategies are optimal.

METHODS

A systematic review and meta-analysis was undertaken using a theory-based approach to classifying and comparing educational interventions for cancer pain. The reference lists of previous reviews and MEDLINE, PsycINFO, and CENTRAL were searched in May 2012. Studies had to be published in a peer-reviewed English language journal and compare the effect on cancer pain intensity of education with usual care. Meta-analyses used standardized effect sizes (ES) and a random effects model. Subgroup analyses compared intervention components categorized using the Michie et al. (Implement Sci 6:42, 2011) capability, opportunity, and motivation behavior (COM-B) model.

RESULTS

Fifteen randomized controlled trials met the criteria. As expected, meta-analysis identified a small-moderate ES favoring education versus usual care (ES, 0.27 [-0.47, -0.07]; P = 0.007) with substantial heterogeneity (I² = 71 %). Subgroup analyses based on the taxonomy found that interventions using "enablement" were efficacious (ES, 0.35 [-0.63, -0.08]; P = 0.01), whereas those lacking this component were not (ES, 0.18 [-0.46, 0.10]; P = 0.20). However, the subgroup effect was nonsignificant (P = 0.39), and heterogeneity was not reduced. Factoring in the variable of individualized versus non-individualized influenced neither efficacy nor heterogeneity.

CONCLUSIONS

The current meta-analysis follows a trend in using theory to understand the mechanisms of complex interventions. We suggest that future efforts focus on interventions that target patient self-efficacy. Authors are encouraged to report comprehensive details of interventions and methods to inform synthesis, replication, and refinement.

The management of chronic pain in important patient subgroups

Chronic pain is a major healthcare issue in Europe and globally, and inadequate or undertreated pain significantly reduces the ability of many patients to participate in ordinary daily activities, adversely affects their employment status and contributes to a substantial rate of depression and anxiety in patients with chronic pain. There is a broad distinction of chronic pain into chronic non-cancer pain and chronic cancer pain, and important subgroups of these include patients with rheumatic and/or orthopaedic diseases, pain syndromes caused by cancer itself and caused by cancer treatment. Despite comprising the majority of non-cancer pain in Europe, chronic non-cancer pain associated with rheumatic diseases and/or orthopaedic conditions is often inadequately managed. Although paracetamol and non-steroidal anti-inflammatory drugs (NSAIDs) play a continuing role in the treatment of chronic rheumatic diseases, accumulating evidence of potential toxicity with both traditional non-selective NSAIDs and selective cyclooxygenase 2 inhibitors has prompted a reassessment of their use. This has particular resonance for the elderly, who are more likely to have significant pain issues than younger patients and are at high risk of NSAID-related adverse events. The use of mild opioids, such as codeine and tramadol, and strong opioids, such as morphine, hydromorphone and oxycodone, may be appropriate where paracetamol and other non-opioid analgesics are ineffective in chronic non-cancer pain. Cancer pain, either related to the underlying disease or caused by cancer treatment, is also a common cause of chronic pain in the elderly. An understanding of individual needs is essential in providing adequate pain relief, which is a central goal of care in all patients with chronic pain.

Differences in pain location, intensity, and quality by pain pattern in outpatients with cancer

BACKGROUND

Pain pattern represents how the individual's pain changes temporally with activities or other factors, but researchers have studied less the pattern of pain than its location, intensity, and quality parameters.

OBJECTIVE

The aim of this study was to explore differences in pain location, intensity, and quality by pattern groups in outpatients with cancer.

METHOD

We conducted a comparative, secondary data analysis of data collected from 1994 to 2007. Seven hundred sixty-two outpatients with cancer completed the 0- to 10-point Pain Intensity Number Scale and the McGill Pain Questionnaire to measure pain location, quality and pattern. From all possible combinations of the 3 types of pain patterns, we created 7 pain pattern groups.

RESULTS

Pain pattern group distribution was as follows: pattern 1 (27%), 2 (24%), 3 (8%), 4 (12%), 5 (3%), 6 (18%), and 7 (8%). A significant higher proportion of patients with continuous pain pattern (patterns 1, 4, 5, and 7) reported pain location in 2 or more sites. Patients with patterns 1, 4, and 7 reported significantly higher worst pain mean scores than did patients with patterns 2, 3, and 6. Patients with pattern 7 reported significantly higher mean scores for the Pain Rating Index-sensory and total number of words selected than did patients with patterns 1, 2, 3, 4, and 6.

CONCLUSIONS

Using pain pattern groups may help nurses to understand temporal changes in cancer pain and to provide more effective pain management, especially if the pain has a continuous component.

IMPLICATIONS FOR PRACTICE

Nurses or clinicians who are taking care of patients with cancer should recognize that pain patterns are associated with pain location, intensity, and quality.

Pharmacological treatment of neuropathic cancer pain: a comprehensive review of the current literature

Neuropathic cancer pain (NCP), commonly encountered in clinical practice, may be cancer-related, namely resulting from nervous system tumor invasion, surgical nerve damage during tumor removal, radiation-induced nerve damage and chemotherapy-related neuropathy, or may be of benign origin, unrelated to cancer. A neuropathic component is evident in about 1/3 of cancer pain cases. Although from a pathophysiological perspective NCP may differ from chronic neuropathic pain (NP), such as noncancer-related pain, clinical practice, and limited publications have shown that these two pain entities may share some treatment modalities. For example, co-analgesics have been well integrated into cancer pain-management strategies and are often used as First-Line options for the treatment of NCP. These drugs, including antidepressants and anticonvulsants, are recommended by evidence-based guidelines, whereas, others such as lidocaine patch 5%, are supported by randomized, controlled, clinical data and are included in guidelines for restricted conditions treatment. The vast majority of these drugs have already been proven useful in the management of benign NP syndromes. Treatment decisions for patients with NP can be difficult. The intrinsic difficulties in performing randomized controlled trials in cancer pain have traditionally justified the acceptance of drugs already known to be effective in benign NP for the management of malignant NP, despite the lack of relevant high quality data. Interest in NCP mechanisms and pharmacotherapy has increased, resulting in significant mechanism-based treatment advances for the future. In this comprehensive review, we present the latest knowledge regarding NCP pharmacological management.

Gene therapy: a potential approach for cancer pain

Chronic pain is experienced by as many as 90% of cancer patients at some point during the disease. This pain can be directly cancer related or arise from a sensory neuropathy related to chemotherapy. Major pharmacological agents used to treat cancer pain often lack anatomical specificity and can have off-target effects that create new sources of suffering. These concerns establish a need for improved cancer pain management. Gene therapy is emerging as an exciting prospect. This paper discusses the potential for viral vector-based treatment of cancer pain. It describes studies involving vector delivery of transgenes to laboratory pain models to modulate the nociceptive cascade. It also discusses clinical investigations aimed at regulating pain in cancer patients. Considering the prevalence of pain among cancer patients and the growing potential of gene therapy, these studies could set the stage for a new class of medicines that selectively disrupt nociceptive signaling with limited off-target effects.

EUS-guided broad plexus neurolysis over the superior mesenteric artery using a 25-gauge needle

OBJECTIVES

Endoscopic ultrasonography (EUS)-guided celiac plexus neurolysis (EUS-CPN) is safe and effective but not beneficial for some patients with extended abdominal cancer. We compared the effectiveness of standard EUS-CPN and EUS-guided broad plexus neurolysis (EUS-BPN) that extends over the superior mesenteric artery (SMA) using a 25-gauge needle.

METHODS

Consecutive patients referred to our quaternary EUS centers were eligible for inclusion. To evaluate the neurolytic spread, contrast was mixed with the neurolytic agent and post-procedure computed tomography scanning was performed. The regions containing the celiac, superior, and inferior mesenteric arteries were divided on the frontal plane into six areas: upper right and left, middle right and left, and lower right and left. The number of contrast-bearing areas after EUS-CPN and EUS-BPN were related to the degree of pain relief achieved.

RESULTS

A total of 67 patients with advanced abdominal cancer were included (34 EUS-CPN and 33 EUS-BPN). The qualitative variables of the two groups did not differ significantly. The EUS-BPN group had more patients with six contrast-bearing areas (42%) than the EUS-CPN group (0%). These patients had significantly better short-term and long-lasting pain relief than patients with less than five contrast-bearing areas. EUS-BPN patients exhibited significantly greater reductions in days 7 and 30 visual analog pain scale scores than EUS-CPN patients.

CONCLUSIONS

Our preliminary data suggested that EUS-BPN using a 25-gauge needle provides patients with advanced abdominal cancer with better pain relief than standard EUS-CPN, and without incurring serious complications. Moreover, it seems that broad neurolysis over the SMA may provide superior analgesia.

Effect of neurolytic celiac plexus block guided by computerized tomography on pancreatic cancer pain

The efficacy of neurolytic coeliac plexus block (NCPB) guided by computerized tomography (CT) was compared with pharmacological therapy in the treatment of pain due to pancreatic cancer. The study involved 56 patients who were placed randomly in either a NCPB group and pharmacological therapy group. At day 1, 7, and 14, the visual analogue scale (VAS) pain scores of the NCPB group were significantly lower than those of the pharmacological therapy group (P < 0.01), with values of 1.3 +/- 0.8 versus 4.1 +/- 0.9, 1.7 +/- 1.1 versus 3.1 +/- 1.1, and 2.0 +/- 1.1 versus 2.9 +/- 0.6, respectively. However, the differences in the improvement of quality of life (QOL) between two groups were not statistically significant. Moreover, the dose of opioid was significantly lower in the patients of group 1 than those of group 2, while the complications related to NCPB were transient. We therefore concludes that CT-guided NCPB with alcohol is an effective and safe modality in the management of intractable pancreatic cancer pain.

Peripheral cannabinoids attenuate carcinoma-induced nociception in mice

We investigated the cannabinoid receptor (CBr) agonists Win55,212-2 (non-selective) and AM1241 (CBr2 selective) and the peripheral receptor (CBr1) in carcinoma-induced pain using a mouse model. Tumors were induced in the hind paw of female mice by local injection of a human oral squamous cell carcinoma (SCC). Significant pain, as indicated by reduction in withdrawal thresholds in response to mechanical stimulation, began at 4 days after SCC inoculation and lasted to 18 days. Local administration of Win55,212-2 (10 mg/kg) and AM1241 (10 mg/kg) significantly elevated withdrawal thresholds, indicating an antinociceptive effect. Ipsilateral expression of CBr1 protein in L5 DRG was significantly upregulated compared to ipsilateral L4 DRG and in normal tissue. These findings support the suggestion that cannabinoids are capable of producing antinociception in carcinoma-induced pain.

An open-label, multi-dose efficacy and safety study of intramuscular tetrodotoxin in patients with severe cancer-related pain

Cancer pain is a prevalent and serious public health issue, and more effective treatments are needed. This study evaluates the analgesic activity of tetrodotoxin, a highly selective sodium channel blocker, in cancer pain. A Phase IIa, open-label, multicenter, dose-escalation study of intramuscular tetrodotoxin was conducted in patients with severe, unrelieved cancer pain. The study design called for six ascending dose levels of intramuscular tetrodotoxin, administered over a four-day treatment period in hospitalized patients, with six patients to be enrolled within each successive dose level. Twenty-four patients underwent 31 courses of treatment at doses ranging from 15 to 90 microg daily, administered in divided doses, over four days. Most patients described transient perioral tingling or other mild sensory phenomena within about an hour of each treatment. Nausea and other toxicities were generally mild, but two patients experienced a serious adverse event, truncal and gait ataxia, that resolved over days. Seventeen of 31 treatments resulted in clinically meaningful reductions in pain intensity, and relief of pain persisted for up to two weeks or longer. Two patients had opioids held due to narcosis concurrent with relief of pain. Somatic, visceral, or neuropathic pain could all respond, but it was not possible to predict which patients were more likely to have an analgesic effect. Tetrodotoxin was overall safe. It effectively relieved severe, treatment-resistant cancer pain in the majority of patients and often for prolonged periods after treatment. It may have a novel mechanism of analgesic effect. Further study is warranted.

Walker 256 Tumor-Bearing Rats as a Model to Study Cancer Pain

An animal model of cancer pain induced by injection of Walker 256 carcinoma cells into the plantar surface of rat hind paw is described. Tumor growth and the occurrence of metastasis were investigated by histopathological analysis. Tumor cell growth was also analyzed plethysmographically by the increase in paw volume. For characterization of pain symptoms, hyperalgesia, allodynia, and spontaneous pain were evaluated 5 to 8 days after cell injection. The volume of the inoculated paw started to increase on day 2 after inoculation, being 40% higher on day 5 after injection. At this time, there was a marked proliferation of tumor cells, with the presence of anaplastic and pleomorphic cells, nucleoli, and atypical mitotic features. On days 7 and 8 after injection, histopathological analysis of popliteal lymph nodes showed the presence of tumor cells. The intraplantar injection of Walker 256 cells caused hyperalgesia at day 5 after cell inoculation. Low-threshold mechanical allodynia was significant 2 days after cell injection, being increased on day 5. In addition, inoculation of tumor cells induced gross behavior, characterized by a significant increase in licking and lifting of the injected paw 5 days after injection. The pain-enhancing effect caused by cell inoculation was partially inhibited by indomethacin on day 2 after cell injection, whereas morphine blocked allodynia on days 2 and 5. These results indicate that intraplantar injection of Walker 256 cells cause pain symptoms characteristic of cancer pain. This experimental model can then be used to investigate new analgesic or anti-tumor drugs.

PERSPECTIVE

This article presents a new animal model for studying cancer pain and metastasis. This model could help in understanding the mechanisms involved in cancer pain symptoms and may be used for the investigation of new analgesic or anti-tumor drugs.

Recent Advances in Understanding Pain Mechanisms Provide Future Directions for Pain Management

PURPOSE/OBJECTIVES

To review current knowledge of neurobiologic mechanisms that generate and maintain chronic pain and to explain how they might be applied in targeting treatment of chronic, inflammatory, and neuropathic pain syndromes.

DATA SOURCES

Published research, literature review articles, and abstracts as well as national statistics.

DATA SYNTHESIS

Treatment for chronic pain associated with cancer and other syndromes remains suboptimal and falls significantly short of clinical needs. Data highlight the role that multiple neurobiologic mechanisms play in modulating and maintaining pain at various levels of the central and peripheral nervous systems. Novel agents have been developed that use a more targeted approach to treating chronic pain.

CONCLUSIONS

A growing body of evidence highlights the critical role that neurobiologic mechanisms play in the initiation and maintenance of chronic pain. A thorough understanding of these mechanisms ultimately may result in targeted treatment approaches that focus on the central and peripheral mechanisms involved in mediation of chronic, inflammatory, and neuropathic pain syndromes.

IMPLICATIONS FOR NURSING

A majority of patients undergoing active treatment for cancer experiences unrelieved pain. By gaining a better understanding of the mechanisms that generate and maintain chronic pain, oncology nurses can promote targeted pain management strategies that incorporate novel therapeutic agents.

Combined neurolytic block of celiac, inferior mesenteric, and superior hypogastric plexuses for incapacitating abdominal and/or pelvic cancer pain

Thirty-five patients with extensive abdominal or pelvic cancer who suffered uncontrolled, diffuse, extensive, and incapacitating pain were treated with a combination of neurolytic celiac plexus block (CPB), inferior mesenteric plexus block (IMPB), and superior hypogastric plexus block (SHGPB). The combination of neurolytic CPB, IMPB, and SHGPB was performed with alcohol, mainly using a transintervetebral disc approach. The combination neurolysis produced effective immediate pain relief in all the patients (visual analog scale (VAS), reduced from 8.8 +/- 0.2 to 0). This pain relief persisted during the first 3 months (VAS, 2.3 +/- 0.5) or until death. Morphine consumption was significantly decreased for the first 1 month (from 96 +/- 29 mg to 31 +/- 10 mg per day) after the neurolysis and thereafter continued to be lower than before the surgery, though not significantly so. No serious complications were observed to have been caused by the neurolytic procedure on the three sympathetic plexuses. Our preliminary clinical results suggest that the combination of neurolytic CPB, IMPB, and SHGPB improves the quality of life of patients who have incapacitating cancer pain, by reducing both the intensity of the pain and their opioid consumption, without serious complications. This combination procedure may provide a new therapeutic option for pain relief in patients with advanced cancer.

Polymer-based biodegradable drug delivery systems in pain management

Pain is an unpleasant sensory experience commonly produced by damage to bodily tissues and it is one of the most significant public health problems, because 21.5% of the world population is estimated to suffer from pain. It results in a total loss of more than 165 billion US dollars each year in the United States alone. Pain reflects a mixture of various pathophysiologic, psychologic, and genetic contributions. When undertreated, pain usually results in serious immune and metabolic upset. Therefore, it requires wide understanding and intensive effort for a better management. Currently, pain control is limited by the modest efficiency of the used drugs, the serious side effects of these drugs, and the inefficacy of conventional drug administration. By the introduction of the technology of biodegradable controlled-release devices into clinical practice, pain control not only benefits from these novel methods for a better delivery of various drugs, but the side effects of the drugs are reduced because use of the devices improves patient compliance. Biodegradable controlled-release devices are polymer-based devices that are designed to deliver drugs locally in a predesigned manner. Recently, there was a high interest in developing these devices for the delivery of different drugs used for pain control. This paper first highlights the dimensions and basics of the problem of pain. Then, it presents an overview of the biodegradable polymers that are used in drug delivery systems and summarizes the studies carried out on these systems in the field of pain management. We refer to our experience in developing a device for multimodal drug delivery, including the use of nanotechnology. Future perspectives are also presented.

A guide to wound managment in palliative care

Wound management in palliative patients is often a very challenging area of care. There are many unique issues that can combine to produce complicated wound management scenarios, including the types of wounds and wound symptoms most commonly affecting palliative care patients, as well as the presence of concurrent disease and associated treatment. Problems exist with the availability of suitable dressings and balancing life expectancy with the goals of wound care. A significant, and possibly under-recognized, issue is the emotional and social distress experienced by these patients, which can be directly attributed to their wound. These problems must all be recognized and addressed in order to manage wounds effectively in this patient population. This article aims to explore these issues and offer advice on the management of wound-related symptoms, with the ultimate goal of improving patients' quality of life.

Emerging analgesics in cancer pain management

Cancer pain is one of the most frequent symptoms in malignant disease, severely impairing the patients' quality of life. The recommendations of the World Health Organization will provide adequate pain relief for the vast majority of cancer patients. However, some patients will suffer from inadequate analgesia or intolerable side effects. Cyclooxygenase-2 (COX-2)-selective non-steroidal anti-inflammatory drugs (NSAIDs), new anticonvulsants, cannabinoids and NMDA receptor antagonists are being developed for these patients. NSAIDs with nitric oxide-releasing moieties are an interesting addition, as this new class of analgesics combines improved analgesic efficacy with higher tolerability. Conotoxins and other drugs such as nicotinic acetylcholinergic receptor agonists will be advantageous only for a few patients in the near future, as side-effect profile and risk of complications, as well as the burden on the patient, often are not worth the additional analgesic benefit.

The Role of Opioids in Cancer Pain Management

Opioids remain an important cornerstone in the treatment of cancer pain. Effective analgesia is obtained in the majority of cancer pain patients with the application of fairly straightforward algorithms using opioids as the main therapy. Many rational treatment algorithms exist. In this tutorial we will describe the role of opioids in the treatment of cancer pain, including a brief overview of cancer pain syndromes, essential aspects of opioid therapy, opioid pharmacology, opioid rotation, properties of the individual opioids, and management of common side effects of opioids.

Cancer pain and anxiety

Anxiety and pain can be understood with a multidimensional framework that accounts for somatic, emotional, cognitive, and behavioral aspects of these conditions. Patients who have cancer or treatment-related pain are more likely to be anxious than cancer patients without pain. Patients with cancer pain and anxiety cause difficult diagnostic dilemmas because some degree of anxiety is a normal response to having a severe medical illness. Furthermore, the somatic symptoms of anxiety often overlap with symptoms related to underlying disease processes or treatment effects. The degree of disruption in a patient's life often is the critical factor in distinguishing normal from maladaptive anxiety. Making an accurate diagnosis will help guide anxiety treatment and screening instruments can facilitate the recognition of those patients in need of further assessment. The relationship between pain and anxiety is complex and bidirectional, with interactions occurring on physiologic and psychologic levels. There are a variety of psychopharmacologic, psychotherapeutic, and complementary/alternative treatments available. A comprehensive approach to care includes these approaches in an individualized way. Terminal sedation is examined as a compassionate option for relieving intractable distress at the end of life.

Recent advances in pharmacotherapy for cancer pain management

PURPOSE

This review provides an outline of several recent advances in drug treatment options and strategies for managing cancer pain.

OVERVIEW

The development of cyclooxygenase-2-selective nonsteroidal anti-inflammatory drugs (NSAIDs) and transmucosal fentanyl citrate provide new pharmacologic options for the treatment of cancer pain. Combinations of opioid agonists and antagonists have provided data on new strategies to balance effective analgesia with analgesic-related adverse effects. In addition, the spectrum of adjuvant agents for the treatment of neuropathic pain has been extended to various antidepressants and topical analgesics. There is continued research on the role of the N-methyl-d-aspartate (NMDA) receptor and, specifically, on NMDA receptor antagonists that may augment analgesia and combat opioid resistance. Finally, a more potent generation of bisphosphonates may lead to improved pain relief for patients with bone metastases.

CLINICAL IMPLICATIONS

With a combination of emerging new clinical research and professional practice experience of the cancer care team, new strategies will continue to be developed and implemented, resulting in the continued improved care of patients with cancer.

Assessment and management of pain in fungating wounds

Pain is a complex phenomenon that affects individuals in different ways. Wound pain is often seen as an inevitable consequence of wound care and many patients may suffer from chronic wound pain. One group of patients that presents a challenge in wound pain management are those with fungating malignant wounds. The effective management of wound pain may be compromised by inappropriate or non-existent pain assessment, the inefficient prescribing of analgesia, and confusion about the appropriate use of dressing products to reduce wound pain. Many healthcare professionals lack knowledge about pain and pain control and hold inappropriate beliefs and attitudes about analgesic medications, in particular relating to opioid drugs. This article aims to address these issues by providing a brief overview of pain physiology followed by strategies for pain assessment and options for the management of pain related to fungating wounds, including pharmacological treatments, wound care techniques and complementary therapies.