Association of mu-opioid receptor expression with lymph node metastasis in esophageal squamous cell carcinoma

Exploring the Effects of Opioid-Related Drugs on the Clinical Outcome of Prostate Cancer Patients Via Integrated Bioinformatics Analysis

Opioids are the primary regimens for perioperative analgesia with controversial effects on oncological survival. The underlying mechanism remains unexplored. This study developed survival-related gene co-expression networks based on RNA-seq and clinical characteristics from TCGA cohort. Two survival-related networks were identified, and drug-induced transcriptional profiles were predicted. Immune cell infiltration algorithm, least absolute shrinkage and selection operator (LASSO) regression, and cox proportional models were executed to explore the correlation between opioid-related drugs and prostate cancer patient prognosis. The opioid receptor agonists, represented by tramadol, were evidenced for anti-survival effects on prostate cancer by facilitating the DNA replication and cell cycle, and immune cell infiltration. Conversely, opioid receptor antagonists showed pro-survival effects. A novel prognostic model containing CNIH2, MCCC1, and Gleason scores was established and validated in two independent cohorts. This study revealed opioids' effect on prostate cancer progression, and provided a novel model to predict these regulations in clinical outcomes.

Effects of Intraoperative Opioid Use and a Combined Anesthesia Protocol in Patients Undergoing Radical Cystectomy for Urothelial Carcinoma of the Bladder-A Single-Center Experience

BACKGROUND

An increased intraoperative opioid dose seems to lead to worse outcomes in several types of cancer. We assessed the effect of intraoperatively administered opioids as well as the type of anesthesia on survival, recurrence rates and major perioperative outcomes in patients who underwent radical cystectomy (RC) for urothelial carcinoma of the urinary bladder.

METHODS

We included patients who underwent open RC at our center between 2015 and 2022. The role of the type and dosage of intraoperative opioid agents, such as remifentanil, sufentanil and morphine milligram equivalents (MME), as well as the type of anesthesia (intravenous only versus intravenous/epidural), was assessed regarding perioperative and long-term outcomes after RC.

RESULTS

A total of 508 patients with a median age of 73 years (IQR: 64-78) were included. Overall, 92 (18%) patients received intravenous anesthesia, whereas 416 (82%) received combined anesthesia. At a median follow-up of 270 days (IQR: 98-808), 108 (21%) deaths and 106 (21%) recurrences occurred. Combined anesthesia was associated with better survival (HR:0.63, 95% CI: 0.4-0.97, p = 0.037) and lower intensive care unit admission rates (OR: 0.49, 95% CI: 0.31-0.77, p = 0.002) in the univariate analysis (unadjusted). The type and dosage of intraoperative opioid agents did not affect long-term survival and recurrence rates, as well as major perioperative outcomes. Nevertheless, the findings of our study were limited by its single-center, retrospective design.

CONCLUSION

The use of intraoperative opioids was not associated with worse outcomes in our cohort, while the use of additional epidural anesthesia seems to be beneficial in terms of overall survival and intensive care unit admissions. Nevertheless, further research is mandatory to validate the safety of opioids in patients undergoing RC.

Activation of epidermal growth factor receptors in triple-negative breast cancer cells by morphine; analysis through Raman spectroscopy and machine learning

Triple negative breast cancer (TNBC) is a very aggressive form of breast cancer, and the analgesic drug morphine has been shown to promote the proliferation of TNBC cells. This article investigates whether morphine causes activation of epidermal growth factor receptors (EGFR), the roles of μ-opioid and EGFR receptors on TNBC cell proliferation and migration. While examining the changes with molecular techniques, we also aimed to investigate the analysis ability of Raman spectroscopy and machine learning-based approach. Effects of morphine on the proliferation and migration of MDA.MB.231 cells were evaluated by MTT and scratch wound-healing tests, respectively. Morphine-induced phosphorylation of the EGFR was analyzed by western blotting in the presence and absence of μ-receptor antagonist naltrexone and the EGFR-tyrosine kinase inhibitor gefitinib. Morphine-induced EGFR phosphorylation and cell migration were significantly inhibited by pretreatments with both naltrexone and gefitinib; however, morphine-increased cell proliferation was inhibited only by naltrexone. While morphine-induced changes were observed in the Raman scatterings of the cells, the inhibitory effect of naltrexone was analyzed with similarity to the control group. Principal component analysis (PCA) of the Raman confirmed the epidermal growth factor (EGF)-like effect of morphine and was inhibited by naltrexone and partly by gefitinib pretreatments. Our in vitro results suggest that combining morphine with an EGFR inhibitor or a peripherally acting opioidergic receptor antagonist may be a good strategy for pain relief without triggering cancer proliferation and migration in TNBC patients. In addition, our results demonstrated the feasibility of the Raman spectroscopy and machine learning-based approach as an effective method to investigate the effects of agents in cancer cells without the need for complex and time-consuming sample preparation. The support vector machine (SVM) with linear kernel automatically classified the effects of drugs on cancer cells with ∼95% accuracy.

The effects of ultrasound-guided QLB and TAPB combined with opioid-free anesthesia (OFA) on clinical efficacy of the patients undergoing abdominal surgery

Background

Although opioids provide effective analgesia for abdominal surgery, they also present serious unwanted side effects. Ultrasound-guild quadratus lumborum block (QLB) and transversus abdominis plane block (TAPB) have been proven to offer long-lasting and efficient analgesia during abdominal surgery. However, the clinical efficacy of ultrasound-guided QLB and TAPB combined with opioid-free anesthesia (OFA) in abdominal surgery remains unclear.

Objective

This study aimed to investigate the impact of ultrasound-guided QLB and TAPB combined with opioid-free anesthesia (OFA) on the clinical efficacy of abdominal surgery.

Methods

A total of 122 patients scheduled for abdominal surgery at People's Hospital of Wanning between March 2021 and April 2022 were enrolled in this study. Participants were randomly divided into two groups: the experimental group (QLB/TAPB + OFA, 62 patients) and the control group (opioid anesthesia, 60 patients). The clinical efficacy of the QLB/TAPB combined with OFA technique was evaluated by analyzing patients' vital signs, postoperative consciousness recovery time, numeric rating scale (NRS) score, and immune function in both groups.

Results

We observed that systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) in experimental group were significantly higher than those in control group after induction (p < 0.05). Heart rate (HR) in experimental group was significantly lower than in the control group at intraoperative 1h (p < 0.05). Additionally, bispectral index (BIS), state entropy (SE), and response entropy (RE) levels in the experimental group were significantly higher than those in the control group (p < 0.05). Furthermore, extubation and awakening time were significantly shorter in the experimental group compared to the control group (p < 0.05). The NRS scores in the experimental group were markedly lower than those in the control group. Moreover, IL-6 and CRP levels in the experimental group were obviously lower than in the control group after postoperative 1d (p < 0.05). Interestingly, IL-6 (p < 0.001), CRP (p < 0.001), and PCT (p = 0.037) levels in female patients of the experimental group were all significantly lower than those in the control group after postoperative 1d.

Conclusions

Ultrasound-guided QLB and TAPB combined with OFA technique can reduce pain intensity and enhance the patients' immune function in abdominal surgery.

Mapping the Evidence for Opioid-Mediated Changes in Malignancy and Chemotherapeutic Efficacy: Protocol for a Scoping Review

BACKGROUND

Numerous reports contend opioids can augment or inhibit malignancy. At present, there is no consensus on the risk or benefit posed by opioids on malignancy or chemotherapeutic activity. Distinguishing the consequences of opioid use from pain and its management is challenging. Additionally, opioid concentration data is often lacking in clinical studies. A scoping review approach inclusive of preclinical and clinical data will improve our understanding of the risk-benefit relationship concerning commonly prescribed opioids and cancer and cancer treatment.

OBJECTIVE

The aim of the study is to map diverse studies spanning from preclinical to clinical regarding opioids with malignancy and its treatment.

METHODS

This scoping review will use the Arksey six stages framework to (1) identify the research question; (2) identify relevant studies; (3) select studies meeting criteria; (4) extract and chart data; (5) collate, summarize, and report results; and (6) conduct expert consultation. An initial pilot study was undertaken to (1) parameterize the extent and scale of existing data for an evidence review, (2) identify key factors to be extracted in systematic charting efforts, and (3) assess opioid concentration as a variable for its relevance to the central hypothesis. Six databases will be searched with no filters: MEDLINE, Embase, CINAHL Complete, Cochrane Library, Biological Sciences Collection, and International Pharmaceutical Abstracts. Trial registries will include ClinicalTrials.gov, Cochrane CENTRAL, International Standard Randomised Controlled Trial Number Registry, European Union Clinical Trials Register, and World Health Organization International Clinical Trials Registry. Eligibility criteria will include preclinical and clinical study data on opioids effects on tumor growth or survival, or alteration on the antineoplastic activity of chemotherapeutics. We will chart data on (1) opioid concentration from human subjects with cancer, yielding a "physiologic range" to better interpret available preclinical data; (2) patterns of opioid exposure with disease and treatment-related patient outcomes; and (3) the influence of opioids on cancer cell survival, as well as opioid-related changes to cancer cell susceptibility for chemotherapeutics.

RESULTS

This scoping review will present results in narrative forms as well as with the use of tables and diagrams. Initiated in February 2021 at the University of Utah, this protocol is anticipated to generate a scoping review by August 2023. The results of the scoping review will be disseminated through scientific conference proceedings and presentations, stakeholder meetings, and by publication in a peer-reviewed journal.

CONCLUSIONS

The findings of this scoping review will provide a comprehensive description of the consequences of prescription opioids on malignancy and its treatment. By incorporating preclinical and clinical data, this scoping review will invite novel comparisons across study types that could inform new basic, translational, and clinical studies regarding risks and benefits of opioid use among patients with cancer.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/38167.

Mu opioid receptor mRNA overexpression predicts poor prognosis among 18 common solid cancers: A pan-cancer analysis

Background

Opioids are widely used for patients with solid tumors during surgery and for cancer pain relief. We conducted a pan-cancer genomic analysis to investigate the prognostic features of Mu opioid receptor (MOR) mRNA expression across 18 primary solid cancers.

Methods

All the data of cancer with MOR mRNA were retrieved from cBioPortal for Cancer Genomics. Logistic regression was used to determine the associations between MOR mRNA expression and clinicopathological features. Log-rank test and Cox regression was used for survival analysis. Subgroup analysis and propensity score matching were also carried out.

Results

7,274 patients, including 1,112 patients with positive MOR mRNA expression, were included for data analyses. Positive MOR mRNA expression was associated with more advanced stage of T (adjusted Odds ratio [OR], 1.176; 95% confidence interval [CI], 1.022-1.354; P=0.024), M (adjusted OR, 1.548; 95% CI, 1.095-2.189; P=0.013) except N (adjusted OR, 1.145; 95% CI, 0.975-1.346; P=0.101), and worse prognosis for overall survival (Hazard ratio [HR] 1.347, 95% CI 1.200-1.512, P&lt;0.001), progression-free survival (HR 1.359, 95% CI 1.220-1.513, P&lt;0.001), disease-free survival (HR 1.269, 95% CI 1.016-1.585, P&lt;0.001) and disease-specific survival (HR 1.474, 95% CI 1.284-1.693, P&lt;0.001). Patients with positive MOR mRNA expression tended to be classified as tumor microenvironment immune types II, representing low PD-L1 and low CD8A expression.

Conclusion

MOR mRNA overexpression is associated with poor prognosis and poor response to PD-L1 therapy.

Effect of Opioids on Survival in Patients with Cancer

Opioids are commonly used for pain management in patients with cancer. They have a range of unwanted effects, including some that potentially influence cancer growth. This article reviews the data assessing the effects of opioids on survival in patients with cancer. Many studies assessing this show an association between opioids and decreased survival. This effect is present even at very low doses of opioids. These studies do not assess causality, so it is not known if it is a direct effect of opioids on survival. As the control groups are not matched to the opioid group it might be that opioids are being used to control pain and patients receiving opioids have more aggressive cancers and it is the underlying cancer which is causing the decreased survival. Furthermore, although some studies allude to different opioids having different effects on survival, often all opioids are pooled in analysis. Future work needs to try to ascertain causality and differentiate between different opioids, pain, and cancer-mediated effects on survival in specific cancer types. Until then, opioids should continue to be used in patients with cancer as part of measures to optimise comfort and quality of life.

The µ-Opioid Receptor in Cancer and Its Role in Perineural Invasion: A Short Review and New Evidence

Cancer is a significant public health problem worldwide. While there has been a steady decrease in the cancer death rate over the last two decades, the number of survivors has increased and, thus, cancer-related sequela. Pain affects the life of patients with cancer and survivors. Prescription opioids continue as the analgesic of choice to treat moderate-to-severe cancer-related pain. There has been controversy on whether opioids impact cancer progression by acting on cancer cells or the tumor microenvironment. The μ-opioid receptor is the site of action of prescription opioids. This receptor can participate in an important mechanism of cancer spread, such as perineural invasion. In this review, current evidence on the role of the μ-opioid receptor in cancer growth is summarized and preliminary evidence about its effect on the cross-talk between sensory neurons and malignant cells is provided.

MOR promotes epithelial-mesenchymal transition and proliferation via PI3K/AKT signaling pathway in human colorectal cancer

The mu-opioid receptor (MOR), a membrane-bound G protein-coupled receptor, is implicated in progression and long-term outcome of several types of tumors. However, the expression and clinical significance of MOR in colorectal cancer (CRC) remain unclear. In this study, a total of 180 paraffin-embedded samples of paired tumors and normal tissues from CRC patients are used to explore expression levels of MOR by immunohistochemistry (IHC). Results show that MOR is highly expressed in tumors compared with that in paired normal tissues (P<0.0001). MOR expression levels are associated with the degree of differentiation (P<0.001) and the regional lymph node metastasis (P<0.001). In addition, a significant difference is also found in the overall survival (OS) between MOR low- and high-expression groups (P=0.002), especially in patients with TNM stage III or IV CRC (P=0.007). Both univariate (P=0.002) and multivariate (P=0.013) analyses indicated that MOR is an independent risk factor associated with CRC prognosis. We further investigate the mechanism in MOR-positive CRC cell line HCT116. The results show that silencing of MOR significantly suppresses epithelial-mesenchymal transition (EMT), in addition to suppressing cell proliferation, migration, and invasion. In addition, the expression of downstream p-AKT is also significantly downregulated, and the above suppression effect could be rescued by PI3K/AKT signaling agonist. We conclude that MOR mediates EMT via PI3K/AKT signaling, facilitating lymph node metastasis and resulting in poor survival of CRC patients. Our findings suggest that MOR is a novel prognostic indicator and the application of opioid receptor antagonists may be a novel therapeutic strategy for CRC patients with high MOR expression.

Antagonists of the Mu-Opioid Receptor in the Cancer Patient: Fact or Fiction?

Purpose of Review

Antagonists of mu-opioid receptor role in cancer progression remains to be elucidated. The objective of this review was to summarize the available evidence on antagonists of mu-opioid receptor effect on tumor progression and prognosis in different types of cancers and an evaluation of the available findings on their mechanism of action.

Recent Findings

We have found studies related to methylnaltrexone (MNTX) and naltrexone (NTX) usage in cancer outcomes-related setting. We found consistent preclinical evidence of a potential action of MNTX and NTX on cancer growth and spread mediated mainly by effect on the opioid growth factor receptor (OGFr) axis, which results in depressed cell replication. However, clinical results are scarce and limited to poor-quality evidence.

Summary

Further high-quality studies are warranted to study antagonists of mu-opioid receptor role as a therapeutic option in different types of cancer, especially in patients where the classical treatment causes unacceptable side effects.

Opioid Receptor Expression in Colorectal Cancer: A Nested Matched Case-Control Study

Background

There is growing interest in the possible effect of perioperative anesthetic management on the growth and spread of cancer. The impact of perioperative use of opioids on cancer recurrence remains controversial and an assessment cannot yet be established based on current publications. This study aimed to assess the differential expression of opioid receptors between healthy and tumor tissues in patients with stage II and III colorectal cancer undergoing elective surgery by immunohistochemistry (IHC).

Methods

Propensity-score matched case-control study nested in a retrospective cohort of patients with stage II or III colorectal. The primary endpoint was the difference in µ-opioid receptor (MOR) expression measured by IHC between tumor and healthy tissue in subject with or without recurrence. Secondary endpoints were to evaluate the differences in Opioid Growth Factor Receptor (OGFR), cyclic adenosine monophosphate (cAMP) production and protein kinase A (PKA) in the matched sample and from a from samples of colorectal cancer stored in the Cancer Genome Atlas (TCGA) and Genotype Tissue Expression Project (GTEx).

Results

There was a significant difference in MOR receptor (median 3 [intequartile range IQR: 1-3] and 0 [IQR: 0-2], P<0.001) and OGFR receptor (median 6 [IQR: 5-6] and 2 [IQR: 1-2], P<0.001) in tumor and control tissue respectively. However, there were no significant differences in cAMP nor PKA expression between both types of tissues and in expression in any of the analyzed variables by recurrence status. The MOR and OGFR expression data from TCGA database were similar to our sample size data with lower expression of MOR and higher expression of OGFR in tumoural samples with a skewed distribution for MOR expression in tumor tissue both in patients with and without recurrence.

Conclusion

In patients with stage II and III colorectal cancer, overall expression of MOR and OGFR was significantly increased but was not different between previously matched patients with or without recurrence. No differences were found in the analyzed metabolic pathway of cAMP-PKA: These results were confirmed by an in silico analysis of samples from the TCGA-GTEx database.

Agonists Specific for κ-Opioid Receptor Induces Apoptosis of HCC Cells Through Enhanced Endoplasmic Reticulum Stress

Cancer pain is an important factor affecting life quality of patients especially in the advanced stage and relieving pain is one of fundamental strategies for cancer treatment. Opioids such as morphine are the most widely used in clinics. However, they have been reported to be associated with the occurrence and development of several types of cancer. Thus, search for an opioid that has analgesic effect and can retard cancer progress simultaneously is critical for cancer management. In this study, we first examined the expression of μ and κ (MOR and KOR) in cell lines and tumor tissues of hepatocellular carcinoma (HCC), a malignant tumor with high mortality, and then compared the effects of opioid receptors-specific agonists on malignant phenotypes of HCC cells in vitro and tumor growth in an HCC xenograft mouse model. KOR and MOR were found to be highly expressed in HCC cell lines and HCC tissues. The KOR-specific agonist U50488h, oxycodone (agonist for both KOR and MOR) and the MOR-specific agonist morphine inhibited HCC cell proliferation, while only U50488h and oxycodone suppressed colony formation and migration of HCC cells. U50488h and oxycodone, but not morphine, induced HCC apoptosis. Further detection of PERK, GRP78 and CHOP revealed that PERK signaling was upregulated by treatment with U50488h, while treatment with the PERK inhibitor GSK2656157 partially reversed the promotion of apoptosis and inhibition of cell proliferation by U50488h, indicating that endoplasmic reticulum stress is associated with its suppressing effect on HCC malignant phenotypes. Similar to the in vitro results, HCC growth was significantly reduced by administration of U50488h and oxycodone, but not by morphine, in the HCC xenograft mouse model. PERK and caspase-3 in the HCC tissues were up-regulated by U50488h treatment as detected by immunohistochemistry and western blotting. Taken together, our results revealed that activation of KOR by U50488h inhibited malignant phenotypes of HCC both in vitro and in vivo, while activation of MOR by morphine did not have such effect. Because of their dual roles in the relief of pain and in the suppression of malignant phenotypes, opioids such as U50488h that act on KOR should be considered as the first choice for HCC management.

Less Well-Known Consequences of the Long-Term Use of Opioid Analgesics: A Comprehensive Literature Review

BACKGROUND

The adverse effects of short-term opioid analgesics are well known and acknowledged; however, the spectrum of the sequelae of long-term use seems less clear. Some effects may remain undetected but still have the potential to cause harm and reduce patients' quality of life.

OBJECTIVE

To review the literature on the adverse effects of long-term opioid therapy.

METHODS

We performed a quasi-systematic search, analyzing articles published in the MEDLINE database between January 2000 and March 2021 that identified adverse effects of opioids used for chronic pain treatment.

RESULTS

Growing evidence indicates that there are multiple serious adverse effects of opioid treatment. Long-term opioid use may have significant effects on the endocrine, immune, cardiovascular, respiratory, gastrointestinal, and neural systems. Studies show that long-term opioid treatment increases the risk of fractures, infections, cardiovascular complications, sleep-disordered breathing, bowel dysfunction, overdose, and mortality. Opioids may potentially affect cancer development. Most consequences of the long-term use of opioids have been identified in studies of patients with non-malignant pain.

CONCLUSION

Studies indicate that long-term use of opioids increases the risk of drug-related events in a significant number of patients. Clinicians should be aware of these complications associated with prescribing opioids, discuss them with patients, prevent complications, if possible, and diagnose them early and manage adequately. More human studies are needed to assess the risk, including trials with individual opioids, because they have different adverse effect profiles.

Solid Tumor Opioid Receptor Expression and Oncologic Outcomes: Analysis of the Cancer Genome Atlas and Genotype Tissue Expression Project

Background

Opioid receptors are expressed not only by neural cells in the central nervous system, but also by many solid tumor cancer cells. Whether perioperative opioids given for analgesia after tumor resection surgery might inadvertently activate tumor cells, promoting recurrence or metastasis, remains controversial. We analysed large public gene repositories of solid tumors to investigate differences in opioid receptor expression between normal and tumor tissues and their association with long-term oncologic outcomes.

Methods

We investigated the normalized gene expression of µ, κ, δ opioid receptors (MOR, KOR, DOR), Opioid Growth Factor (OGFR), and Toll-Like 4 (TLR4) receptors in normal and tumor samples from twelve solid tumor types. We carried out mixed multivariable logistic and Cox regression analysis on whether there was an association between these receptors' gene expression and the tissue where found, i.e., tumor or normal tissue. We also evaluated the association between tumor opioid receptor gene expression and patient disease-free interval (DFI) and overall survival (OS).

Results

We retrieved 8,780 tissue samples, 5,852 from tumor and 2,928 from normal tissue, of which 2,252 were from the Genotype Tissue Expression Project (GTEx) and 672 from the Cancer Genome Atlas (TCGA) repository. The Odds Ratio (OR) [95%CI] for gene expression of the specific opioid receptors in the examined tumors varied: MOR: 0.74 [0.63-0.87], KOR: 1.27 [1.17-1.37], DOR: 1.66 [1.48-1.87], TLR4: 0.29 [0.26-0.32], OGFR: 2.39 [2.05-2.78]. After controlling all confounding variables, including age and cancer stage, there was no association between tumor opioid receptor expression and long-term oncologic outcomes.

Conclusion

Opioid receptor gene expression varies between different solid tumor types. There was no association between tumor opioid receptor expression and recurrence. Understanding the significance of opioid receptor expression on tumor cells remains elusive.

Antitumor Anesthetic Strategy in the Perioperatory Period of the Oncological Patient: A Review

The stress response triggered by the surgical aggression and the transient immunosuppression produced by anesthetic agents stimulate the inadvertent dispersion of neoplastic cells and, paradoxically, tumor progression during the perioperative period. Anesthetic agents and techniques, in relation to metastatic development, are investigated for their impact on long-term survival. Scientific evidence indicates that inhaled anesthetics and opioids benefit immunosuppression, cell proliferation, and angiogenesis, providing the ideal microenvironment for tumor progression. The likely benefit of reducing their use, or even replacing them as much as possible with anesthetic techniques that protect patients from the metastatic process, is still being investigated. The possibility of using "immunoprotective" or "antitumor" anesthetic techniques would represent a turning point in clinical practice. Through understanding of pharmacological mechanisms of anesthetics and their effects on tumor cells, new perioperative approaches emerge with the aim of halting and controlling metastatic development. Epidural anesthesia and propofol have been shown to maintain immune activity and reduce catecholaminergic and inflammatory responses, considering the protective techniques against tumor spread. The current data generate hypotheses about the influence of anesthesia on metastatic development, although prospective trials that determinate causality are necessary to make changes in clinical practice.

Can Acute Postoperative Pain Management After Tumour Resection Surgery Modulate Risk of Later Recurrence or Metastasis?

Background

Cancer is a leading cause of mortality worldwide, but death is rarely from the primary tumour: Rather it is multi-organ dysfunction from metastatic disease that is responsible for up to 90% of cancer-related deaths. Surgical resection of the primary tumour is indicated in 70% of cases. The perioperative stress response, tissue hypoxia at the site of surgery, and acute pain contribute to immunosuppression and neo-angiogenesis, potentially promoting tumour survival, proliferation, and metastasis. Poorly controlled acute postoperative pain decreases Natural Killer (NK) immune cell activity, which could potentially facilitate circulating tumour cells from evading immune detection. This consequently promotes tumour growth and distal metastasis.

Methods

We conducted a comprehensive literature search for links between acute pain and cancer outcomes using multiple online databases. Relevant articles from January 1st, 2010 to September 1st, 2021 were analysed and appraised on whether postoperative pain control can modulate the risk of recurrence, metastasis, and overall cancer survival.

Results

Although experimental and retrospective clinical data suggest a plausible role for regional anaesthesia in cancer outcome modulation, this has not been supported by the single, largest prospective trial to date concerning breast cancer. While there are mixed results on anaesthesiology drug-related interventions, the most plausible data relates to total intravenous anaesthesia with propofol, and to systemic administration of lidocaine.

Conclusion

The hypothesis that anaesthetic and analgesic technique during cancer surgery could influence risk of subsequent recurrence or metastasis has been prevalent for >15 years. The first, large-scale definitive trial among women with breast cancer found robust equivalent findings between volatile anaesthesia with opioid analgesia and regional anaesthesia. Therefore, while regional anaesthesia during tumour resection does not seem to have any effect on cancer outcomes, it remains plausible that other anaesthetic techniques (e.g. total intravenous anaesthesia and systemic lidocaine infusion) might influence oncologic outcome in other major tumour resection surgery (e.g. colorectal and lung). Therefore, another large trial is needed to definitively answer these specific research questions. Until such evidence is available, perioperative analgesia for cancer surgery of curative intent should be based on patient co-morbidity and non-cancer endpoints, such as optimising analgesia and minimising postoperative complications.

Morphine promotes the malignant biological behavior of non-small cell lung cancer cells through the MOR/Src/mTOR pathway

BACKGROUND

Morphine, a µ-opioid receptor (MOR) agonist, has been shown to be related to the activity of cancer cells, and a higher morphine dosage reduces the survival time of patients with lung cancer. However, the effect of morphine on the malignant behavior of lung cancer cells remains unclear. The aim of this study was to investigate the specific molecular mechanism by which morphine regulates the malignant biological behavior of non-small cell lung cancer.

METHODS

Immunofluorescence staining and Western blot analyses were performed to detect MOR expression. H460 non-small cell lung cancer cells were used in this study, and cell proliferation, the cell cycle and apoptosis were evaluated using Cell Counting Kit-8 (CCK-8) and flow cytometry assays, respectively. Cell migration and invasion were detected using wound healing and Transwell assays. The effect of morphine on lung cancer development in vivo was examined by performing a xenograft tumor assay following morphine treatment.

RESULTS

Morphine promoted the growth of H460 cells both in vivo and in vitro. Morphine enhanced cell migration and invasion, modified cell cycle progression through the S/G₂ transition and exerted an antiapoptotic effect on H460 cells. Additionally, morphine increased Rous sarcoma oncogene cellular homolog (Src) phosphorylation and activated the phosphoinositide 3 kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway. Treatment with the MOR antagonist methylnaltrexone (MNTX) and the Src inhibitor protein phosphatase 1 (PP1) reduced the phosphorylation induced by morphine. Furthermore, MNTX, PP1, and the PI3K/AKT inhibitor deguelin reversed the antiapoptotic effect of morphine on lung cancer cells.

CONCLUSION

Morphine promotes the malignant biological behavior of H460 cells by activating the MOR and Src/mTOR signaling pathways.

Opioids and Breast Cancer Recurrence: A Systematic Review

Breast cancer has the greatest epidemiological impact in women. Opioids represent the most prescribed analgesics, both in surgical time and in immediate postoperative period, as well as in chronic pain management as palliative care. We made a systematic review analyzing the literature's evidence about the safety of opioids in breast cancer treatment, focusing our attention on the link between opioid administration and increased relapses. The research has been conducted using the PubMed database. Preclinical studies, retrospective and prospective clinical studies, review articles and original articles were analyzed. In the literature, there are several preclinical in vitro and in vivo studies, suggesting a possible linkage between opioids administration and progression of cancer disease. Nevertheless, these results are not confirmed by clinical studies. The most recent evidence reassures the safety of opioids during surgical time as analgesic associated with anesthetics drugs, during postoperative period for optimal cancer-related pain management and in chronic use. Currently, there is controversial evidence suggesting a possible impact of opioids on breast cancer progression, but to date, it remains an unresolved issue. Although there is no conclusive evidence, we hope to arouse interest in the scientific community to always ensure the best standards of care for these patients.

Targeting the mu-Opioid Receptor for Cancer Treatment

PURPOSE OF REVIEW

Opioids are still the most effective and widely used treatments for acute and chronic pain in cancer patients. This review focuses on the impact of opioids and mu-opioid receptors (MOR) on tumor progression and providing new ideas for targeting the MOR in cancer treatment.

RECENT FINDINGS

Studies estimated that opioids facilitate tumor progression and are related to the worse prognosis in cancer patients. As the primary receptor of opioids, MOR is involved in the regulation of malignant transformation of tumors and participating in proliferation, invasion, metastasis, and angiogenesis. MOR may be a new molecular marker of malignant tumors and thus become a new target for cancer therapy, which may be beneficial to the outcomes of cancer patients.

Early maternal separation enhances melanoma progression in adult female mice by immune mechanisms

Maternal separation (MS) is a risk factor for major depressive disorder. Both cancer and depression seem to share a common biological link. Here, we evaluated the progression of melanoma and the underlying mechanisms related to this progression, namely cell proliferation and apoptosis, in adult female mice exposed to MS. Female C57BL/6 mice were exposed to MS for 60 min/day during the first 2 postnatal weeks (here called MS mice) or left undisturbed (here called non-MS mice). Melanoma cells were inoculated subcutaneously into the axillary region of adult animals, and tumor progression was evaluated for 25 days. Adult MS mice presented depressive-like behavior and working memory deficits. MS accelerated murine melanoma growth by mechanisms related to decreased apoptosis and increased cell proliferation rate, such as increased expression of IL-6 and mTOR. MS stimulated eukaryotic elongation factor 2 expression and increased the number of circulating monocytes and DNA damage in peripheral blood leukocytes, an effect associated with oxidative DNA damage. In conclusion, MS accelerated the progression of murine melanoma by mechanisms related to tumor proliferation and apoptosis, revealing a relationship between adverse childhood experiences and cancer progression, particularly melanoma.

Association of Mu-Opioid Receptor(MOR) Expression and Opioids Requirement With Survival in Patients With Stage I-III Pancreatic Ductal Adenocarcinoma

Background

The use of opioids in patients with metastatic pancreatic ductal adenocarcinoma (PDAC) is associated with shorter survival and not dependent on the expression of the mu-opioid receptor (MOR). The role of opioid use and MOR expression in stage I-III PDAC has not been investigated.

Methods

We conducted retrospective study in patients with stage I-III PDAC. MOR expression and OPRM1 gene expression in tumour tissue and non-tumour tissue was measured. Primary endpoints were overall survival (OS) and disease-free survival (DFS). Secondary endpoints included perineural invasion, intraoperative sufentanil consumption, and length of stay. We performed a subgroup group analysis to evaluate the interaction between levels of MOR expression, amount of opioids use (high versus low) and its association with survival.

Results

A total of 236 patients were enrolled in this study.There were no significantly difference in OS rates in patients with high versus low levels of MOR (1-year OS: 65.2% versus 70.6%, P=0.064; 3-year: 31.4% versus 35.8%, P=0.071; 5-year: 19.4% versus. 16.2%, P=0.153, respectively) in the tumours. The DFS rates between the groups were no significantly difference. Of note, a high expression of MOR combined with high opioid consumption was associated with poor prognosis in stage I-III PDAC patients. Tumor expressing high levels of MOR show higher rates of perineural invasion.

Conclusion

MOR is not an independent predictor of poor survival in stage I-III PDAC but associated with perineural invasion. Patients requiring high amounts of opioids intraoperatively show worse outcome if they are expressing high levels of MOR.

Morphine promotes tumorigenesis and cetuximab resistance via EGFR signaling activation in human colorectal cancer

Morphine, a mu-opioid receptor (MOR) agonist, has been extensively used to treat advanced cancer pain. In particular, in patients with cancer metastasis, both morphine and anticancer drugs are given simultaneously. However, evidence showed that morphine might be a risk factor in promoting the tumor's malignant potential. In this study, we report that treatment with morphine could activate MOR and lead to the promotion of proliferation, migration, and invasion in HCT116 and DLD1 colorectal cancer (CRC) cells with time-concentration dependence. Moreover, morphine can also contribute to cetuximab's drug resistance, a targeted drug widely used to treat advanced CRC by inducing the activation of epidermal growth factor receptor (EGFR). The cell phenotype includes proliferation, migration, invasion, and drug resistance, which may be reversed by MOR knockdown or adding nalmefene, the MOR receptor antagonist. Receptor tyrosine kinase array analysis revealed that morphine selectively induced the transactivation of EGFR. EGFR transactivation resulted in the activation of ERK1/2 and AKT. In conclusion, morphine induces the transactivation of EGFR via MOR. It activates the downstream signal pathway AKT-MTOR and RAS-MAPK, increases proliferation, migration, and invasion, and promotes resistance to EGFR inhibitors in a CRC cell line. Furthermore, we verified that EGFR inhibition by cetuximab strongly reversed the protumoral effects of morphine in vitro and in vivo. Collectively, we provide evidence that morphine-EGFR signaling might be a promising therapeutic target for CRC patients, especially for cetuximab-resistant CRC patients.

Mu-Opioid Receptor Expression in Laryngeal Cancer

OBJECTIVES

Expression of mu-opioid receptors (MORs) has not been investigated in head and neck cancer. In this study, we aimed to assess the expression of opioids receptors in laryngeal cancer, compared to adjacent non-malignant tissue.

STUDY DESIGN

A retrospective case series in a single academic center.

METHODS

Sixty-four specimens were taken from 32 matched patients, diagnosed with laryngeal-carcinoma (20 supraglottic and 12 glottic), and were analyzed using immunohistochemical stains for MOR. All sections were examined and evaluated with a semi-quantitative analysis for staining intensity and cell count for a percentage of the positively stained cells. Survival of patients was compared based on MOR expression.

RESULTS

MOR staining intensity was significantly increased in laryngeal-carcinoma compared to the normal tissue adjacent to the carcinoma (P = 0.019). The percentage of stained cells in non-involved supraglottis was significantly higher compared to the non-involved glottis (P = 0.022), yet this difference was no longer found between supra- and glottic-carcinoma tissues.

CONCLUSION

MOR may play a role in the laryngeal cancer environment, as the expression in tumor cells alters from adjacent non-cancerous tissue.

Opioids and cancer prognosis: A summary of the clinical evidence

Pain is a common and devastating symptom among cancer patients. It can be caused by the cancer itself or by certain therapies like surgery, radiation or chemotherapy. Opioids are the first line of treatment for moderate to severe cancer-related pain. Opioids alone or in combination with non-opioid analgesics and adjuvant medications are important components for pain management during the perioperative period for cancer patients. Opioids act on the μ-opioid receptor (MOR), which is expressed in cancer cells and non-malignant cells of the tumor microenvironment. Retrospective studies suggest an association between the expression of MOR in cancers and shorter survival. In addition, recent evidence suggests that opium use and prescription opioids can influence clinical oncological outcomes. In this review, we will summarize the clinical evidence regarding the effect of opioid administration and survival in patients with cancer as well as the current evidence involving MOR expression and cancer progression.

The role of regional anaesthesia in the emerging subspecialty of onco-anaesthesia: a state-of-the-art review

Cancer accounts for millions of deaths globally each year, predominantly due to recurrence and metastatic disease. The majority of patients with primary solid organ cancers require surgery, however, some degree of tumour dissemination related to surgery is inevitable. The surgical stress response and associated immunosuppression, pain, inflammation, tissue hypoxia and angiogenesis have all been implicated in promoting tumour survival, proliferation and recurrence. Regional anaesthesia was hypothesised to reduce the surgical stress response and immunosuppression, minimise the need for volatile anaesthesia and reduce pain and opioid requirements, thus mitigating pro-tumour pathways associated with the peri-operative period and improving long-term oncological outcomes. While some retrospective studies suggested an association between regional anaesthesia and reduced cancer recurrence, the first large randomised controlled trial on the effect of anaesthetic technique on cancer outcome found no significant difference between paravertebral regional anaesthesia and volatile anaesthesia with opioid analgesia in patients undergoing breast cancer surgery. Randomised controlled trials on the long-term oncological outcomes of regional anaesthesia in other tumour types are ongoing. The focus on how peri-operative interventions, especially regional anaesthesia, during cancer resection surgery, may enhance short-term recovery and perhaps influence long-term outcome has spawned the global emergence of the subspecialty of onco-anaesthesia. This review aims to discuss the most recent evidence on the use of regional anaesthesia in cancer surgery and the significance of its role in onco-anaesthesia.

The association of prescription opioid use with incident cancer: A Surveillance, Epidemiology, and End Results-Medicare population-based case-control study

BACKGROUND

Cancer is the second leading cause of death globally, and researchers seek to identify modifiable risk factors Over the past several decades, there has been ongoing debate whether opioids are associated with cancer development, metastasis, or recurrence. Basic science, clinical, and observational studies have produced conflicting results. The authors examined the association between prescription opioids and incident cancers using the Surveillance, Epidemiology, and End Results (SEER)-Medicare database. A complex relation was observed between prescription opioids and incident cancer, and cancer site may be an important determinant.

METHODS

By using linked SEER cancer registry and Medicare claims from 2008 through 2013, a case-control study was conducted examining the relation between cancer onset and prior opioid exposure. Logistic regression was used to account for differences between cases and controls for 10 cancer sites.

RESULTS

Of the population studied (n = 348,319), 34% were prescribed opioids, 79.5% were white, 36.9% were dually eligible (for both Medicare and Medicaid), 13% lived in a rural area, 52.7% had ≥1 comorbidity, and 16% had a smoking-related diagnosis. Patients exposed to opioids had a lower odds ratio (OR) associated with breast cancer (adjusted OR, 0.96; 95% CI, 0.92-0.99) and colon cancer (adjusted OR, 0.90; 95% CI, 0.86-0.93) compared with controls. Higher ORs for kidney cancer, leukemia, liver cancer, lung cancer, and lymphoma, ranging from lung cancer (OR, 1.04; 95% CI, 1.01-1.07) to liver cancer (OR, 1.19; 95% CI, 1.08-1.31), were present in the exposed population.

CONCLUSIONS

The current results suggest that an association exists between prescription opioids and incident cancer and that cancer site may play an important role. These findings can direct future research on specific patient populations that may benefit or be harmed by prescription opioid exposure.

Increased mu-opioid receptor expression is associated with reduced disease-free and overall survival in laryngeal squamous cell carcinoma

BACKGROUND

Expression of the mu-opioid receptor (MOR) is associated with poor long-term outcomes in various types of cancer. The association between MOR expression and clinical outcomes in laryngeal squamous cell carcinoma (LSCC) is not clear.

METHODS

This retrospective study included patients who underwent laryngectomy for LSCC. The expression pattern of the MOR protein and OPRM1 gene in tumours and corresponding adjacent non-carcinoma specimens was measured. Propensity score matching was used to minimise bias. The primary endpoints were overall survival (OS) and disease-free survival (DFS). The secondary endpoints were intraoperative sufentanil consumption, grade of surgical complications according to the Clavien-Dindo classification, and hospital length of stay.

RESULTS

A total of 207 LSCC patients were enrolled. After propensity score matching, there was a significant difference in DFS between groups at 1, 3, and 5 yr (60.2% vs 81.2%, P=0.019; 39.4% vs 50.2%, P=0.026; 37.5% vs 42.5%, P=0.023, respectively) in patients with high MOR expression. The OS rates at 1, 3, and 5 yr were significantly lower in the high MOR expression group (81.2% vs 93.2%, P=0.027; 57.7% vs 78.3%, P<0.001; 42.5% vs 60.3%, P<0.001, respectively). The multivariate analysis indicated that high MOR expression was associated with worse DFS and OS (hazard ratio: 1.52, 95% confidence interval: 1.07, 2.25, P=0.034; hazard ratio: 1.42, 95% confidence interval: 1.17, 2.34, P=0.032).

CONCLUSION

High MOR expression may be associated with poor prognosis in patients with LSCC, suggesting that MOR could be used as a valuable molecular biomarker to predict prognosis of LSCC patients.

Opioids and Cancer Mortality

OPINION STATEMENT

Opioids are the gold standard for the treatment of cancer-related pain. Preclinical studies have associated opioids with cancer progression and overall survival. In mice models, opioids have been shown to possess pro-tumor activity secondary to immunosuppression, migration of tumor cells, increased activity of vascular endothelial growth factor receptors, and angiogenesis leading to tumor progression. In contrast, opioids have also been associated with having antitumor activity by activation of apoptosis and phagocytosis. However, high-quality randomized controlled trials in humans that are focused on the association between opioids and survival in cancer patients are lacking, which underscores the importance of being cautious when interpreting the results of the preclinical studies. Cancer-related pain is complex and multifactorial and may worsen as the disease progresses leading to higher opioid utilization. Moreover, cancer pain by itself has been associated with poor survival. The survival in these advanced cancer patients taking opioids may be more likely to be associated with cancer progression and not the opioid use. Adequate treatment of cancer pain has the potential to improve quality of life and performance status, highlighting the importance of continuing to use opioids to manage pain efficiently. More research is clearly needed.

Mu Opioid Receptor 1 (MOR-1) Expression in Colorectal Cancer and Oncological Long-Term Outcomes: A Five-Year Retrospective Longitudinal Cohort Study

Preclinical evidence has shown increased expression of mu opioid receptor 1 (MOR-1) in colorectal cancer although its association with disease-free and overall survival (DFS and OS) has not been investigated. We hypothesized that MOR-1 was overexpressed in tumor samples compared to normal tissue and this was associated with decreased DFS and OS. We carried out a retrospective study assessing the association of MOR-1 tumor expression with long-term outcomes by immunohistochemistry in normal and tumor samples from 174 colorectal cancer patients. The primary endpoint was five years of DFS. Secondary endpoints were five years of OS, the difference in MOR-1 expression between normal and tumor tissue and the occurrence of postoperative complications. Multivariable Cox regression showed no significant association between MOR-1 expression and DFS (HR 0.791, 95% CI 0.603–1.039, p = 0.092). MOR-1 expression was higher in tumor tissue compared to non-tumor tissue. No associations were found between MOR-1 expression and OS or postoperative complications. These findings suggest that although MOR-1 is over-expressed in colorectal cancer samples there is no association to increased risk of recurrence or mortality. Future studies are warranted to elucidate the role of cancer stage, genetic polymorphism, and quantitative assessment of MOR-1 over-expression on long-term outcomes in colorectal cancer.

Effects of Intraperitoneal and Intrathecal Morphine Analgesia on the Expression of μ-Opioid Receptors in Bone Cancer Pain Rats

Backgrounds

This study compared analgesic effects and μ-opioid receptor expression levels during long-term intraperitoneal and intrathecal treatment in a bone cancer pain rat.

Methods

Twenty-four female Sprague-Dawley rats were injected Walker 256 tumor cells into the femur to create a bone cancer pain model. The control group was injected with saline intraperitoneally and intrathecally. The intraperitoneal group was injected with morphine intraperitoneally and saline intrathecally. The intrathecal group was injected saline intraperitoneally and morphine intrathecally. Changes in pain threshold, μ-opioid receptor expression levels in spinal cord, and tumor tissue were compared between 3 groups.

Results

The intrathecal morphine group and the intraperitoneal group showed no difference in analgesia effects (P > .05). Western blot and immunohistochemical staining of μ-opioid receptors demonstrated that its level in the intrathecal group was significantly lower than the intraperitoneal group (P < .05) and without significant difference with the control group (P > .05). The expression levels of μ-opioid receptor in the spinal cord tissue did not reveal a difference among these 3 groups (P > .05).

Conclusion

Intrathecal group and intraperitoneal group showed significant difference in μ-opioid receptor expressions although with no difference in analgesia effects. Long-term intrathecal morphine administration provided similar analgesia compared to systemic morphine.

Effects of Intraoperative Opioid Use on Recurrence-Free and Overall Survival in Patients With Esophageal Adenocarcinoma and Squamous Cell Carcinoma

BACKGROUND

Perioperative opioid use is associated with poor survival in patients with esophageal squamous cell carcinoma. The most common histological type of esophageal cancer in western countries is adenocarcinoma. The objective of this study was to evaluate the association between intraoperative opioid consumption and survival in patients with adenocarcinoma and squamous cell carcinoma of the esophagus.

METHODS

Records of patients who had undergone esophageal cancer surgery between January 2000 and January 2017 were reviewed. Comparisons were made between patients who received high versus low intraoperative doses of opioids. Groups were divided using the recursive partitioning method. Multicovariate Cox proportional hazards models were fitted to evaluate the impact of intraoperative opioid use on recurrence-free survival (RFS) and overall survival (OS).

RESULTS

For patients with esophageal squamous cell carcinoma, the univariable analysis indicated that lower opioid dosages (<710 μg fentanyl equivalents) were significantly associated with worse RFS (P = .009) and OS (P = .002). With the adjustment of age, stage, and adjuvant chemotherapy, multivariable analysis confirmed significant associations between higher dosages of intraoperative fentanyl equivalents and better RFS (P = .002; hazard ratio [HR], 0.376; 95% confidence interval [CI], 0.201~0.704). Likewise, higher intraoperative fentanyl equivalents administered was associated with improved OS (P = .002; HR, 0.346; 95% CI, 0.177~0.676). In the adenocarcinoma population, the association between intraoperative opioid dosage and RFS (P = .15) or OS (P = .36) was not significant from univariable analysis. With the adjustment of age, body mass index, tumor staging, neoadjuvant chemotherapy, and adjuvant chemotherapy, multivariable analysis demonstrated marginal significant association between intraoperative fentanyl equivalents and RFS (P = .0866; HR, 0.806; 95% CI, 0.629~1.032). The association between intraoperative fentanyl equivalents and OS was not significant (P = .51).

CONCLUSIONS

The results of this study indicate that the amounts of intraoperative opioids used are associated with recurrence and OS in patients with esophageal squamous cell carcinoma. The association between the dose of intraoperative opioids used and RFS was marginally significant in patients with adenocarcinoma. Until confirmation on our findings by future studies, opioids should continue to be a key component of balanced anesthesia in patients with esophageal cancer.

Influence of perioperative anaesthetic and analgesic interventions on oncological outcomes: a narrative review

Surgery is an important treatment modality for the majority of solid organ cancers. Unfortunately, cancer recurrence following surgery of curative intent is common, and typically results in refractory disease and patient death. Surgery and other perioperative interventions induce a biological state conducive to the survival and growth of residual cancer cells released from the primary tumour intraoperatively, which may influence the risk of a subsequent metastatic disease. Evidence is accumulating that anaesthetic and analgesic interventions could affect many of these pathophysiological processes, influencing risk of cancer recurrence in either a beneficial or detrimental way. Much of this evidence is from experimental in vitro and in vivo models, with clinical evidence largely limited to retrospective observational studies or post hoc analysis of RCTs originally designed to evaluate non-cancer outcomes. This narrative review summarises the current state of evidence regarding the potential effect of perioperative anaesthetic and analgesic interventions on cancer biology and clinical outcomes. Proving a causal link will require data from prospective RCTs with oncological outcomes as primary endpoints, a number of which will report in the coming years. Until then, there is insufficient evidence to recommend any particular anaesthetic or analgesic technique for patients undergoing tumour resection surgery on the basis that it might alter the risk of recurrence or metastasis.

Long-Term Oncologic Outcomes, Opioid Use, and Complications after Esophageal Cancer Surgery

Effective and adequate opioid use and prevention of postoperative complications are important for enhanced recovery after surgery. We examined the effects of postoperative opioid use and postoperative complications on overall survival and recurrence-free survival after esophageal cancer surgery. This retrospective cohort study analyzed the records of patients diagnosed with esophageal cancer who underwent the Ivor Lewis operation between January 2005 and December 2011. We collected data on total opioid use for 8 days postoperatively, as well as information on postoperative complications (Clavien-Dindo classification). One hundred and twenty-one patients were included in the final analysis. Total opioid use was not significantly associated with overall survival (p = 0.520) and recurrence-free survival (p = 0.818). In contrast, the hazard ratio of postoperative overall survival was significantly higher with respect to Clavien-Dindo classification 1-2 (hazard ratio: 2.009, p = 0.046), 3a-3b (hazard ratio: 5.759, p < 0.001), and 4a-5 (hazard ratio: 3.982, p = 0.020) complications compared to no complications. Additionally, the hazard ratio of the recurrence-free survival was significantly higher in class 1-2 complications (hazard ratio: 2.336, p = 0.028) compared to none. Our study demonstrates that postoperative opioid use is not associated with survival and recurrence-free survival after esophageal cancer surgery, while postoperative complications may increase the hazard ratio for survival and recurrence-free survival.

Intravenous opioid drug abuse as an independent risk factor for supraglottic squamous cell carcinoma-A case-control study

OBJECTIVES

Intravenous opioid drug abuse (IVDA) was previously correlated with laryngeal cancer. However, discrimination of this correlation by anatomical subsites has not yet been described. In this study, we aim to further establish the association between IVDA and laryngeal squamous cell carcinoma (SCC) and to indicate the laryngeal subsites that are predisposed for this correlation.

DESIGN

A retrospective matched case-control study.

SETTING AND PARTICIPANTS

Patients diagnosed with supraglottic SCC (SG-SCC) between 1996 and 2016 treated in a tertiary academic referral centre were enrolled to the case group. The control group comprised of matched patients diagnosed with glottis SCC (G-SCC). Matching was based on gender, age and socio-economic rank.

MAIN OUTCOME MEASURES

Variables studies as risk factors included the following: smoking, alcohol consumption, history of IVDA and infectious diseases. The variables were tested for association with the 2 groups and with each other.

RESULTS

Forty-eight patients with SG-SCC were matched with 48 patients with G-SCC. IVDA rates significantly increased among patients with SG-SCC. Of the SG-SCC group, 18.8% had a positive history for IVDA compared with 2.1% of the G-SCC (P = .008). A history of IVDA was found to be a risk factor for SG-SCC, independent of smoking, excessive alcohol and socio-economic status. The odds ratio for patients with an IVDA history to have SG-SCC relatively to G-SCC was 10.846 (95% CI: 1.3-89.4).

CONCLUSIONS

Intravenous opioid drug abuse represents an independent risk factor for SG-SCC. The pathogenesis should be investigated not just as a risk factor, as opioids are commonly used for pain management in oncologic patients.

Association of high-dose postoperative opioids with recurrence risk in esophageal squamous cell carcinoma: reinterpreting ERAS protocols for long-term oncologic surgery outcomes

Esophageal squamous cell carcinoma (ESCC) is associated with a poor prognosis and high postoperative recurrence rate. Although postoperative opioid use has been associated with cancer recurrence, its relevance in ESCC has not been determined. Therefore, this study investigated whether high-dose postoperative opioid use was associated with recurrence risk in patients with ESCC. For this retrospective analysis, the medical records of patients who were diagnosed with ESCC and who underwent surgery between January 2006 and December 2010 in the National Cancer Center, Korea were evaluated. Total opioid administration over a 10-day period, from during surgery to postoperative day 9, was calculated. A cutoff value was determined using receiver operating characteristic curve analysis, and patients were classified into the high-use and low-use groups. The primary and secondary outcomes of the study were freedom from recurrence and overall survival, respectively. After propensity score matching, the effect of opioid use on freedom from recurrence and overall survival was evaluated using the Kaplan-Meier method. The final analysis set included 258 patients. The cumulative opioid dose cutoff point was 1783.5 mg of oral morphine. High-dose postoperative opioid use was a significant factor affecting recurrence (Hazard ratio [HR], 2.162; 95% confidence interval [CI], 1.583-2.954; P < 0.0001). In contrast, postoperative opioid use was not associated with death (HR, 1.274; 95% CI, 0.922-1.761; P = 0.1422). In patients with ESCC, compared with low-dose opioid use, high-dose intraoperative and postoperative opioid use was significantly associated with an increased risk of recurrence. However, opioid dosage did not affect overall survival.

Influence of opioids on immune function in patients with cancer pain: from bench to bedside

In patients with cancer, opioids are principally used for the management of acute surgical and chronic cancer-related pain. However, opioids have many non-analgesic effects, including direct and indirect effects on cancer cells and on anti-tumour immunity (NK cells, macrophages and T-cells). Direct effects on immune cells are manifested via opioid and non-opioid toll-like receptors, whereas indirect effects are manifested via the sympathetic nervous system and hypothalamic-pituitary-adrenal axis. Opioids can also decrease/alter immune cell infiltration into the tumour micro-environment. Animal models have shown that this is not a class effect, in that morphine and fentanyl suppress NK cell cytotoxicity; buprenorphine does not affect NK cell cytotoxicity, whereas tramadol increases NK cell cytotoxicity, reducing metastasis. In healthy individuals, morphine suppresses and fentanyl enhances NK cell cytotoxicity. In patients undergoing surgery, fentanyl decreased and tramadol increased NK cell cytotoxicity; clinical outcomes were not determined. Meta-analyses of opioid-sparing surgical studies report an association between improved recurrence-free and/or overall survival with regional/neuraxial anaesthesia compared with systemic opioids. In patients receiving opioids for non-surgical cancer-related pain, morphine has variable effects on immunity; clinical outcomes were not assessed. Although there is a potential association between systemic opioid administration and shorter survival in cancer patients with a prognosis of months to years, studies have not been designed to primarily assess survival, as a consequence of which causality cannot be apportioned. Pain is immunosuppressive, so analgesia is important. Opioids for cancer-related pain will continue to be recommended until definitive data on the effects of opioids on clinical outcomes in specific patient groups becomes available.

LINKED ARTICLES

This article is part of a themed section on Emerging Areas of Opioid Pharmacology. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.14/issuetoc.

A systematic review of the impact of pain on overall survival in patients with cancer

PURPOSE

Pain commonly occurs in cancer patients, and has been associated with shorter survival. However, the importance of pain is less clear when analyzed with other known prognostic variables. This systematic review was performed to better understand how pain impacts overall survival (OS) in common cancers when key clinical variables are included in multivariate analysis.

METHODS

A Medline search was completed to find studies examining the relationship between pain, clinical variables, and OS in patients with breast, colorectal, lung, or prostate cancer. Multivariate analysis included known prognostic variables including age, performance status, disease burden, and laboratory parameters.

RESULTS

Fifty studies met inclusion criteria. In patients with breast, colorectal, and lung cancer, pain was not a significant prognostic factor for OS on multivariate analysis in most studies. In contrast, several studies suggest that pain is an independent prognostic factor for OS in advanced prostate cancer, even when relevant clinical prognostic variables are included. However, analgesic use was often used as a surrogate for prostate cancer pain, making it difficult to determine whether pain or opioid exposure was more important in influencing survival.

CONCLUSIONS

Pain may be associated with shorter survival in patients with cancer, but the mechanism for this relationship is unknown. The available evidence is insufficient to definitively determine if pain independently influences survival in patients with breast, colorectal, or lung cancer. The majority of studies in prostate cancer show pain to be an independent prognostic factor for OS, and often also incorporate opioid analgesic use in multivariate analysis. Prospective studies are needed to better understand how opioid utilization and pain may affect cancer progression and survival in diverse malignancies.

Endogenous Opiates and Behavior: 2015

This paper is the thirty-eighth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2015 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

The mu opioid receptor: A new target for cancer therapy?

Mu opioids are among the most widely used drugs for patients with cancer with both acute and chronic pain as well as in the perioperative period. Several retrospective studies have suggested that opioid use might promote tumor progression and as a result negatively impact survival in patients with advanced cancer; however, in the absence of appropriate prospective validation, any changes in recommendations for opioid use are not warranted. In this review, the authors present preclinical and clinical data that support their hypothesis that the mu opioid receptor is a potential target for cancer therapy because of its plausible role in tumor progression. The authors also propose the hypothesis that peripheral opioid antagonists such as methylnaltrexone, which reverses the peripheral effects of mu opioids but maintains centrally mediated analgesia and is approved by the US Food and Drug Administration for the treatment of opioid-induced constipation, can be used to target the mu opioid receptor.

MOR1 expression in gastric cancer: a biomarker associated with poor outcome

BACKGROUND

At present, the expression of MOR1 and its function in gastric cancer remains unclear with evidence suggesting that it is to be involved in tumor progression and metastasis. The study was to assess the clinicopathologic relevance and prognostic value of MOR1 expression in gastric cancer.

METHODS

Real-time quantitative RT-PCR and immunohistochemical staining were used to detect MOR1 expression in primary gastric cancerous surgical specimens and adjacent nontumorous tissues.

RESULTS

High MOR1 expression was detected in cancerous tumor compared with their adjacent nontumorous tissues. In addition, the chi-square test revealed that high MOR1 expression was significantly correlated with depth of invasion (p = 0.006), lymph node metastasis (p = 0.001), distant metastasis (p = 0.017), and TNM staging (p = 0.027). Moreover, Kaplan-Meier analysis revealed a significant association between MOR1 expression and overall survival. High expression of MOR1 was identified as an independent and significant predictor gene of reduced postoperative survival.

CONCLUSION

We conclude that MOR1 expression may be a useful biomarker for better prediction of the clinical outcome and management of gastric cancer patients.