Cancer-nerve interplay in cancer progression and cancer-induced bone pain.

INTRODUCTION: Cancer-induced bone pain (CIBP) is one of the most common and debilitating complications associated with bone metastasis. Although our understanding of the precise mechanism is limited, it has been known that bone is densely innervated, and that CIBP is elicited as a consequence of increased neurogenesis, reprogramming, and axonogenesis in conjunction with sensitization and excitation of sensory nerves (SNs) in response to the noxious stimuli that are derived from the tumor microenvironment developed in bone. Recent studies have shown that the sensitized and excited nerves innervating the tumor establish intimate communications with cancer cells by releasing various tumor-stimulating factors for tumor progression. APPROACHES: In this review, the role of the interactions of cancer cells and SNs in bone in the pathophysiology of CIBP will be discussed with a special focus on the role of the noxious acidic tumor microenvironment, considering that bone is in nature hypoxic, which facilitates the generation of acidic conditions by cancer. Subsequently, the role of SNs in the regulation of cancer progression in the bone will be discussed together with our recent experimental findings. CONCLUSION: It is suggested that SNs may be a newly-recognized important component of the bone microenvironment that contribute to not only in the pathophysiology of CIBP but also cancer progression in bone and dissemination from bone. Suppression of the activity of bone-innervating SNs, thus, may provide unique opportunities in the treatment of cancer progression and dissemination, as well as CIBP.

Worst Pain Severity Profiles of Oncology Patients Are Associated With Significant Stress and Multiple Co-Occurring Symptoms.

Little is known about the associations between pain, stress, and co-occurring symptoms in oncology patients. Purpose was to identify subgroups of patients with distinct worst pain profiles and evaluate for differences among the subgroups in demographic and clinical characteristics, as well as stress and symptom scores. Oncology outpatients (n = 1305) completed questionnaires prior to their second or third chemotherapy cycle. Worst pain intensity was assessed 6 times over 2 chemotherapy cycles using a 0 to 10 numeric rating scale. The 371 patients (28.4%) who had ≤1 occurrence of pain over the 6 assessments were classified as the None class. For the remaining 934 patients whose data were entered into the latent profile analysis, 3 distinct worst pain profiles were identified (ie Mild [12.5%], Moderate [28.6%], Severe [30.5%]). Compared to None class, Severe class had fewer years of education and a lower annual income; were less likely to be employed and married; less likely to exercise on a regular basis, had a higher comorbidity burden, and a worse functional status. Compared to None class, Severe class reported higher levels of general, disease-specific, and cumulative life stress and lower levels of resilience, as well as higher levels of depressive symptoms, anxiety, fatigue, sleep disturbance, and cognitive dysfunction. This study is the first to identify distinct worst pain profiles in a large sample of oncology patients receiving chemotherapy and associated risk factors. PERSPECTIVE: Unrelieved pain remains a significant problem for oncology patients receiving chemotherapy. High levels of stress and co-occurring symptoms contribute to a more severe pain profile in these patients.

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.

TRP channels in cancer pain.

Chronic pain is a common symptom experienced during cancer progression. Additionally, some patients experience bone pain caused by cancer metastasis, which further complicates the prognosis. Cancer pain is often treated using opioid-based pharmacotherapy, but these drugs possess several adverse effects. Accordingly, new mechanisms for cancer pain management are being explored, including transient receptor potential channels (TRPs). TRP ion channels are expressed in several tissues and play a key role in pain detection, especially TRP vanilloid 1 (TRPV1) and TRP ankyrin 1 (TRPA1). In the present review, we describe the role of TRPV1 and TRPA1 involved in cancer pain mechanisms. Several studies have revealed that the administration of TRPV1 or TRPA1 agonists/antagonists and TRPV1 or TRPA1 knockdown reduced sensitivity to nociception in cancer pain models. TRPV1 was also found to be involved in various models of cancer-induced bone pain (CIBP), with TRPV1 expression reportedly enhanced in some models. These studies have demonstrated the TRPV1 or TRPA1 association with cancer pain in models induced by tumour cell inoculation into the bone cavity, hind paw, mammary fat pad, and sciatic nerve in mice or rats. To date, only resiniferatoxin, a TRPV1 agonist, has been evaluated in clinical trials for cancer pain and showed preliminary positive results. Thus, TRP channels are potential targets for managing cancer-related pain syndromes.

Short course radiotherapy and delayed surgery for locally advanced rectal cancer in frail patients: is it a valid option?

OBJECTIVE: The endpoint of the present study was to evaluate the outcomes of short-course radiotherapy (SCRT) and SCRT with delayed surgery (SCRT-DS) on a selected subgroup of frail patients with locally advanced middle/low rectal adenocarcinoma. METHODS: From January 2008 to December 2018, a total of 128 frail patients with locally advanced middle-low rectal adenocarcinoma underwent SCRT and subsequent restaging for eventual delayed surgery. Rates of complete pathological response, down-staging, disease free survival (DFS) and overall survival (OS) were analyzed. RESULTS: 128 patients completed 5 × 5 Gy pelvic radiotherapy. 69 of these were unfit for surgery; 59 underwent surgery 8 weeks (average time: 61 days) after radiotherapy. Downstaging of T occurred in 64% and down-staging of N in 50%. The median overall survival (OS) of SCRT alone was 19.5 months. The 1-year, 2-year, 3-year and 5-year OS was 48%, 22%, 14% and 0% respectively. In the surgical group, the median disease-free survival (DFS) and median OS were, respectively, 67 months (95% CI 49.8-83.1 months) and 72.1 months (95% CI 57.5-86.7 months). The 1, 2, 3, 5-year OS was 88%, 75%, 51%, 46%, respectively. Post-operative morbidity was 22%, mortality was 3.4%. CONCLUSIONS: Frail patients with advanced rectal cancer are often "unfit" for long-term neoadjuvant chemoradiation. A SCRT may be considered a valid option for this group of patients. Once radiotherapy is completed, patients can be re-evaluated for surgery. If feasible, SCRT and delayed surgery is the best option for frail patients.

Usefulness of the measurement of neurite outgrowth of primary sensory neurons to study cancer-related painful complications.

Abnormal outgrowth of sensory nerves is one of the important contributors to pain associated with cancer and its treatments. Primary neuronal cultures derived from dorsal root ganglia (DRG) have been widely used to study pain-associated signal transduction and electrical activity of sensory nerves. However, there are only a few studies using primary DRG neuronal culture to investigate neurite outgrowth alterations due to underlying cancer-related factors and chemotherapeutic agents. In this study, primary DRG sensory neurons derived from mouse, non-human primate, and human were established in serum and growth factor-free conditions. A bovine serum albumin gradient centrifugation method improved the separation of sensory neurons from satellite cells. The purified DRG neurons were able to maintain their heterogeneous subpopulations, and displayed an increase in neurite growth when exposed to cancer-derived conditioned medium, while they showed a reduction in neurite length when treated with a neurotoxic chemotherapeutic agent. Additionally, a semi-automated quantification method was developed to measure neurite length in an accurate and time-efficient manner. Finally, these exogenous factors altered the gene expression patterns of murine primary sensory neurons, which are related to nerve growth, and neuro-inflammatory pain and nociceptor development. Together, the primary DRG neuronal culture in combination with a semi-automated quantification method can be a useful tool for further understanding the impact of exogenous factors on the growth of sensory nerve fibers and gene expression changes in sensory neurons.

TNFα promotes oral cancer growth, pain, and Schwann cell activation.

Oral cancer is very painful and impairs a patient's ability to eat, talk, and drink. Mediators secreted from oral cancer can excite and sensitize sensory neurons inducing pain. Cancer mediators can also activate Schwann cells, the peripheral glia that regulates neuronal function and repair. The contribution of Schwann cells to oral cancer pain is unclear. We hypothesize that the oral cancer mediator TNFα activates Schwann cells, which further promotes cancer progression and pain. We demonstrate that TNFα is overexpressed in human oral cancer tissues and correlates with increased self-reported pain in patients. Antagonizing TNFα reduces oral cancer proliferation, cytokine production, and nociception in mice with oral cancer. Oral cancer or TNFα alone increases Schwann cell activation (measured by Schwann cell proliferation, migration, and activation markers), which can be inhibited by neutralizing TNFα. Cancer- or TNFα-activated Schwann cells release pro-nociceptive mediators such as TNFα and nerve growth factor (NGF). Activated Schwann cells induce nociceptive behaviors in mice, which is alleviated by blocking TNFα. Our study suggests that TNFα promotes cancer proliferation, progression, and nociception at least partially by activating Schwann cells. Inhibiting TNFα or Schwann cell activation might serve as therapeutic approaches for the treatment of oral cancer and associated pain.

The Experience of Complex Pain Dynamics in Oncology Outpatients: A Longitudinal Qualitative Analysis.

BACKGROUND: Few qualitative studies of cancer patients' everyday experiences with pain exist within the large body of cancer pain research. Longitudinal qualitative studies are particularly sparse, and no studies have qualitatively described patients' pain experience over time during participation in a self-management intervention. OBJECTIVE: To longitudinally describe patients' pain experiences during a 10-week pain self-management intervention. METHODS: This qualitative study was embedded in a randomized controlled trial of a psychoeducational pain management intervention. The data consisted of transcribed audio recordings of each intervention session. An emergent, interpretive approach was used in this longitudinal qualitative analysis. RESULTS: Forty-two adult patients were included. The analysis revealed the strikingly dynamic nature of individual patient's pain experiences. Multiple facets of pain contributed to its dynamic nature, including pain in changing locations, co-occurring sources of pain, and varying patterns of pain intensity over time. For individual patients, the cumulative effect of these multiple facets resulted in a phenomenon we termed "complex pain dynamics." CONCLUSION: The results contribute to knowledge about the dynamic nature of cancer patients' pain experiences over a relatively short period. They suggest the need for a new paradigm for management of pain in cancer patients and raise questions about the interpretation of randomized controlled trial results in the absence of qualitative data. IMPLICATIONS FOR PRACTICE: Frequent assessments and reassessments of pain are needed in cancer patients with the ongoing development of highly individualized self-management strategies. A large repertoire of interventions is needed to effectively manage pain in cancer patients over time.

A Novel Syngeneic Immunocompetent Mouse Model of Head and Neck Cancer Pain Independent of Interleukin-1 Signaling.

BACKGROUND: Pain is one of the first presenting symptoms in patients with head and neck cancer, who often develop chronic and debilitating pain as the disease progresses. Pain is also an important prognostic marker for survival. Unfortunately, patients rarely receive effective pain treatment due to our limited knowledge of the mechanisms underlying head and neck cancer pain (HNCP). Pain is often associated with neuroinflammation and particularly interleukin (IL)-1 signaling. The purpose of this study is to develop a novel syngeneic model of HNCP in immunocompetent mice to examine the contribution of IL-1 signaling. METHODS: Male C57BL/6 mice were injected with a murine model of human papillomavirus (HPV+)-induced oropharyngeal squamous cell carcinoma in their right hindlimb to induce tumor growth. Pain sensitivity was measured via von Frey filaments. Spontaneous pain was assessed via the facial grimace scale. IL-1ß was measured by quantifying gene expression via quantitative polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA). RESULTS: Pain hypersensitivity and spontaneous pain develop quickly after the implantation of tumor cells, a time when tumor volume is still insignificant. Spinal and circulating IL-1ß levels are significantly elevated in tumor-bearing mice. Blocking IL-1 signaling either by intrathecal administration of interleukin-1 receptor antagonist (IL-1ra) or by genetic deletion (interleukin-1 receptor knockout [Il1r1-/-]) does not alleviate HNCP. CONCLUSIONS: We established the first syngeneic model of HNCP in immunocompetent mice. Unlike inflammatory or nerve-injured pain, HNCP is independent of IL-1 signaling. These findings challenge the common belief that pain results from tissue compression or IL-1 signaling in patients with head and neck cancer.

Do Cohabitants Reliably Complete Questionnaires for Patients in a Terminal Cancer Stage when Assessing Quality of Life, Pain, Depression, and Anxiety?

BACKGROUND: Patients with bone metastases often are unable to complete quality of life (QoL) questionnaires, and cohabitants (such as spouses, domestic partners, offspring older than 18 years, or other people who live with the patient) could be a reliable alternative. However, the extent of reliability in this complicated patient population remains undefined, and the influence of the cohabitant's condition on their assessment of the patient's QoL is unknown. QUESTIONS/PURPOSES: (1) Do QoL scores, measured by the 5-level EuroQol-5D (EQ-5D-5L) version and the Patient-reported Outcomes Measurement Information System (PROMIS) version 1.0 in three domains (anxiety, pain interference, and depression), reported by patients differ markedly from scores as assessed by their cohabitants? (2) Do cohabitants' PROMIS-Depression scores correlate with differences in measured QoL results? METHODS: This cross-sectional study included patients and cohabitants older than 18 years of age. Patients included those with presence of histologically confirmed bone metastases (including lymphoma and multiple myeloma), and cohabitants must have been present at the clinic visit. Patients were eligible for inclusion in the study regardless of comorbidities, prognosis, prior surgery, or current treatment. Between June 1, 2016 and March 1, 2017 and between October 1, 2017 and February 26, 2018, all 96 eligible patients were approached, of whom 49% (47) met the selection criteria and were willing to participate. The included 47 patient-cohabitant pairs independently completed the EQ-5D-5L and the eight-item PROMIS for three domains (anxiety, pain, and depression) with respect to the patients' symptoms. The cohabitants also completed the four-item PROMIS-Depression survey with respect to their own symptoms. RESULTS: There were no clinically important differences between the scores of patients and their cohabitants for all questionnaires, and the agreement between patient and cohabitant scores was moderate to strong (Spearman correlation coefficients ranging from 0.52 to 0.72 on the four questionnaires; all p values < 0.05). However, despite the good agreement in QoL scores, an increased cohabitant's depression score was correlated with an overestimation of the patient's symptom burden for the anxiety and depression domains (weak Spearman correlation coefficient of 0.33 [95% confidence interval 0.08 to 0.58]; p = 0.01 and moderate Spearman correlation coefficient of 0.52 [95% CI 0.29 to 0.74]; p < 0.01, respectively). CONCLUSION: The present findings support that cohabitants might be reliable raters of the QoL of patients with bone metastases. However, if a patient's cohabitant has depression, the cohabitant may overestimate a patient's symptoms in emotional domains such as anxiety and depression, warranting further research that includes cohabitants with and without depression to elucidate the effect of depression on the level of agreement. For now, clinicians may want to reconsider using the cohabitant's judgement if depression is suspected. CLINICAL RELEVANCE: These findings suggest that a cohabitant's impressions of a patient's quality of life are, in most instances, accurate; this is potentially helpful in situations where the patient cannot weigh in. Future studies should employ longitudinal designs to see how or whether our findings change over time and with disease progression, and how specific interventions-like different chemotherapeutic regimens or surgery-may factor in.

Continuous subcutaneous infusion for pain control in dying patients: experiences from a tertiary palliative care center.

BACKGROUND: Continuous subcutaneous infusion (CSCI) via ambulatory infusion pump (AIP) is a valuable method of pain control in palliative care. When using CSCI, low-dose methadone as add-on to other opioids might be an option in complex pain situations. This study aimed to investigate the effects, and adverse effects, of CSCI for pain control in dying patients, with particular interest in methadone use. METHODS: This was an observational cohort study. Imminently dying patients with pain, admitted to specialized palliative inpatient wards and introduced on CSCI, were monitored daily by staff for symptoms (Integrated Palliative Care Outcome Scale - IPOS), sedation (Richmond Agitation and Sedation Scale - RASS), performance status (Eastern Cooperative Oncology Group - ECOG) and delirium (Confusion Assessment Method - CAM). RESULTS: Ninety-three patients with a median survival of 4 days were included. Of the 47 patients who survived ≥3 days, the proportion of patients with severe/overwhelming pain decreased from 45 to 19% (p < 0.001) after starting CSCI, with only a moderate increase in morphine equivalent daily dose of opioids (MEDD). Alertness was marginally decreased (1 point on the 10-point RASS scale, p = 0.001), whereas performance status and prevalence of delirium, regardless of age, remained unchanged. Both patients with methadone as add-on (MET, n = 13) and patients with only other opioids (NMET, n = 34), improved in pain control (p < 0.05 and 0.001, respectively), despite that MET patients had higher pain scores at baseline (p < 0.05) and were on a higher MEDD (240 mg vs.133 mg). No serious adverse effects demanding treatment stop were reported. CONCLUSIONS: CSCI via AIP is an effective way to reduce pain in dying patients without increased adverse effects. Add-on methadone may be beneficial in patients with severe complex pain.

The current clinical use of adjuvant analgesics for refractory cancer pain in Japan: a nationwide cross-sectional survey.

BACKGROUND: Although adjuvant analgesics are used to treat opioid-refractory cancer pain, there is insufficient evidence to support this practice and limited data to guide the choice depending on cancer pain pathophysiology, dose titration and starting dose. This survey aimed to clarify the current use of adjuvant analgesics for treating opioid-refractory cancer pain. METHODS: In this cross-sectional study, we sent an online survey questionnaire to 208 certified palliative care specialists. Primary outcomes were (i) effective pathophysiological mechanism of cancer pain and (ii) initiating doses and time period to the first response to each adjuvant analgesic therapy. RESULTS: In total, 87 (42%) palliative care specialists responded. Of all patients with cancer pain, 40% of patients (median) with refractory cancer pain were prescribed adjuvant analgesics. Additionally, 94.3, 93.1 and 86.2% of palliative care specialists found dexamethasone/betamethasone effective for neuropathic pain caused by tumor-related spinal cord compression, pregabalin effective for malignant painful radiculopathy and dexamethasone/betamethasone effective for brain tumor or leptomeningeal metastases-related headache, respectively. The median starting dose of pregabalin, dexamethasone/betamethasone, lidocaine and ketamine were 75, 4, 200, and 50 mg/day, respectively, and the median time to the first response of those medications were 5, 3, 2 and 3 days, respectively. CONCLUSIONS: Many palliative care specialists select adjuvant analgesics depending on the pathophysiological mechanism of cancer pain in each case. They used such adjuvant analgesics in low doses for cancer pain with short first-response periods.

A narrative review of buprenorphine in adult cancer pain.

INTRODUCTION: Adult cancer pain is a disease state battled on a global scale. Proper pain management is essential to prevent health complications and promote patient well-being. Due to the opioid misuse crisis in the United States, providers are looking for alternatives to traditional opioids used for adult cancer pain. Buprenorphine has a unique pharmacologic profile, allowing it to be delivered in noninvasive ways; thus, it offers an alternative to traditional options. Randomized controlled trials have shown improved pain scores with transdermal buprenorphine, and they showed reductions in pain scores and increased improvement in quality of life scores versus other opioids. Sublingual buprenorphine has more limited, but promising data for reducing cancer pain. AREAS COVERED: We provide a narrative review of pathophysiological pathways of pain in cancer, how they are treated, and the unique properties of buprenorphine. Guidelines addressing pain management during cancer treatment are assessed to identify buprenorphine's place in therapy. Recent literature reporting efficacy and safety of buprenorphine use in pain management during cancer treatment will be presented. EXPERT OPINION: Current literature shows strong data for transdermal buprenorphine and promising data for sublingual buprenorphine. With this evidence, buprenorphine could have a more expanded role in managing adult cancer pain.

The role and pharmacological characteristics of ATP-gated ionotropic receptor P2X in cancer pain.

Many factors are involved in the development of cancer pain, which is a serious complication of cancer and affects the quality of life of patients, Normally, drugs are used to relieve pain in clinic, but the effect is not satisfactory to patients. Therefore, it is necessary to explore the molecular basis of the pathogenesis of cancer pain and carry out targeted therapy. Fortunately, the important role of P2X purine receptors dependent on ATP ion channels in the development of cancer pain has been recognized. In the development of cancer, ATP concentration in the tumor microenvironment is high enough to activate P2X purine receptors, sensitive peripheral receptors, enhance sensory nerve fiber information transmission, sensitize the central nervous system, and induce or aggravate pain. Here, we outlined the role of P2X purine receptors in the development of cancer, and discussed the intrinsic correlation between P2X purine receptors and cancer pain. Moreover, we also explored the pharmacological properties of P2X antagonists or inhibitors to inhibit cancer pain, and hope to provide some value for the treatment of cancer pain in the future. In short, up-regulation of P2X expression can induce or aggravate cancer pain, while reducing P2X expression level can inhibit cancer pain. Therefore, P2X may be another potential pharmacological target for the treatment of cancer pain.

Spinal Wnt5a Plays a Key Role in Spinal Dendritic Spine Remodeling in Neuropathic and Inflammatory Pain Models and in the Proalgesic Effects of Peripheral Wnt3a.

Wnt signaling represents a highly versatile signaling system, which plays critical roles in developmental morphogenesis as well as synaptic physiology in adult life and is implicated in a variety of neural disorders. Recently, we demonstrated that Wnt3a is able to recruit multiple noncanonical signaling pathways to alter peripheral sensory neuron function in a nociceptive modality-specific manner. Furthermore, several studies recently reported an important role for Wnt5a acting via canonical and noncanonical signaling in spinal processing of nociception in a number of pathologic pain disorders. Here, using diverse molecular, genetic, and behavioral approaches in mouse models of pain in vivo, we report a novel role for Wnt5a signaling in nociceptive modulation at the structural level. In models of chronic pain, using male and female mice, we found that Wnt5a is released spinally from peripheral sensory neurons, where it recruits the tyrosine kinase receptors Ror2 and Ryk to modulate dendritic spine rearrangement. Blocking the Wnt5a-Ryk/Ror2 axis in spinal dorsal horn neurons prevented activity-dependent dendritic spine remodeling and significantly reduced mechanical hypersensitivity induced by peripheral injury as well as inflammation. Moreover, we observed that peripheral Wnt3a signaling triggers the release of Wnt5a in the spinal cord, and inhibition of spinal Wnt5a signaling attenuates the functional impact of peripheral Wnt3a on nociceptive sensitivity. In conclusion, this study reports a novel role for the Wnt signaling axis in coordinating peripheral and spinal sensitization and shows that targeting Wnt5a-Ryk/ROR2 signaling alleviates both structural and functional mechanisms of nociceptive hypersensitivity in models of chronic pain in vivoSIGNIFICANCE STATEMENT There is a major need to elucidate molecular mechanisms underlying chronic pain disorders to develop novel therapeutic approaches. Wnt signaling represents a highly versatile signaling system, which plays critical roles during development and adult physiology, and it was implicated in several diseases, including chronic pain conditions. Using mouse models, our study identifies a novel role for Wnt5a signaling in nociceptive modulation at the spinal cord level. We observed that Wnt5a recruits Ror2 and Ryk receptors to enhance dendritic spine density, leading to nociceptive sensitization. Blocking the Wnt5a-Ryk/Ror2 interaction in the spinal dorsal horn prevented spine remodeling and significantly reduced inflammatory and neuropathic hypersensitivity. These findings provide proof-of-concept for targeting spinal Wnt signaling for alleviating nociceptive hypersensitivity in vivo.

Opioid receptors beyond pain control: The role in cancer pathology and the debated importance of their pharmacological modulation.

Stimulation of opioid receptors is widely used for relieving cancer pain in patients with advanced cancer. The expression of tissue opioid receptors varies depending on the types of cancer and it is regulated by several factors. This review provides a focused overview of the current evidence for the role of opioid receptors in modulating cancer progression, a discussion of the proposed underlying mechanisms and the pharmacological activity of opioid agonists and antagonists. Conflicting evidence from preclinical and clinical studies suggests the possible involvement of opioid receptor agonists in both the development and suppression of human cancer. Some retrospective clinical studies also show a possible detrimental effect on long-term patient outcomes. Among the opioid receptor agonists, morphine has been extensively studied in various cancer types. Moreover, various pathological processes of human cancer are affected by opioid receptor agonists, such as tumour growth, angiogenesis and immunosuppression. These findings highlight the functional value of opioid receptors in human cancer, and a potential double role of opioid receptor agonists and antagonists in human cancer treatment.

Clinically Actionable Strategies for Studying Neural Influences in Cancer.

Neuro-glial activation is a recently identified hallmark of growing cancers. Targeting tumor hyperinnervation in preclinical and small clinical trials has yielded promising antitumor effects, highlighting the need of systematic analysis of neural influences in cancer (NIC). Here, we outline the strategies translating these findings from bench to the clinic.

Antinociceptive activity of Schinus terebinthifolia leaf lectin (SteLL) in sarcoma 180-bearing mice.

ETHNOPHARMACOLOGY RELEVANCE: Schinus terebinthifolia Raddi leaves have been used in folk medicine due to several properties, including antitumor and analgesic effects. The variable efficacy and adverse effects of analgesic drugs have motivated the search for novel antinociceptive agents. It has been reported that the S. terebinthifolia leaf lectin (SteLL) has antitumor activity against sarcoma 180 in mice. AIM OF THE STUDY: This work aimed to evaluate whether SteLL would reduce cancer pain using an orthotopic tumor model. MATERIALS AND METHODS: A sarcoma 180 cell suspension was inoculated into the right hind paws of mice, and the treatments (150 mM NaCl, negative control; 10 mg/kg morphine, positive control; or SteLL at 1 and 2 mg/kg) were administered intraperitoneally 24 h after cell inoculation up to 14 days. Spontaneous nociception, mechanical hyperalgesia, and hot-plate tests were performed. Further, the volume and weight of the tumor-bearing paws were measured. RESULTS: SteLL (2 mg/kg) improved limb use during ambulation. The lectin (1 and 2 mg/kg) also inhibited mechanical hyperalgesia and increased the latency time during the hot-plate test. Naloxone was found to reverse this effect, indicating the involvement of opioid receptors. The tumor-bearing paws of mice treated with SteLL exhibited lower volume and weight. CONCLUSION: SteLL reduced hyperalgesia due to sarcoma 180 in the paws of mice, and this effect can be related to its antitumor action.

Quality of life among Ethiopian cancer patients.

PURPOSE: Cancer is of increasing prevalence in less-developed countries. However, research on the patients' quality of life (QoL) in these countries is very limited. The aim of this study was to examine QoL of cancer patients in Africa. METHOD: A sample of 256 cancer patients treated in an Ethiopian hospital was examined with the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire EORTC QLQ-C30, the Multidimensional Fatigue Inventory, and the Hospital Anxiety and Depression Scale. A group of 1664 German cancer patients served as a comparison group. RESULTS: Most of the scales of the EORTC QLQ-C30 showed acceptable reliability in the Ethiopian sample. Compared with the German cancer patients, the Ethiopian patients showed lower QoL in most dimensions, especially in financial difficulties, physical functioning, pain, and appetite loss (effect sizes between 0.52 and 0.75). Illiteracy, tumor stage, and treatment (surgery and chemotherapy) were associated with QoL in the Ethiopian sample. QoL was strongly correlated with fatigue, anxiety, and depression. CONCLUSION: The EORTC QLQ-C30 is a suitable instrument for measuring QoL in Ethiopia. The detriments in QoL in the Ethiopian patients indicate specific cancer care needs for the patients in a developing country.