Marie Fallon

Strategies to Manage the Adverse Effects of Oral Morphine: An Evidence-Based Report

Successful pain management with opioids requires that adequate analgesia be achieved without excessive adverse effects. By these criteria, a substantial minority of patients treated with oral morphine (10% to 30%) do not have a successful outcome because of (1) excessive adverse effects, (2) inadequate analgesia, or (3) a combination of both excessive adverse effects along with inadequate analgesia. The management of excessive adverse effects remains a major clinical challenge. Multiple approaches have been described to address this problem. The clinical challenge of selecting the best option is enhanced by the lack of definitive, evidence-based comparative data. Indeed, this aspect of opioid therapeutics has become a focus of substantial controversy. This study presents evidence-based recommendations for clinical-practice formulated by an Expert Working Group of the European Association of Palliative Care (EAPC) Research NETWORK: These recommendations highlight the need for careful evaluation to distinguish between morphine adverse effects from comorbidity, dehydration, or drug interactions, and initial consideration of dose reduction (possibly by the addition of a co analgesic). If side effects persist, the clinician should consider options of symptomatic management of the adverse effect, opioid rotation, or switching route of systemic administration. The approaches are described and guidelines are provided to aid in selecting between therapeutic options.

Multicenter, Double-Blind, Randomized, Placebo-Controlled, Parallel-Group Study of the Efficacy, Safety, and Tolerability of THC:CBD Extract and THC Extract in Patients with Intractable Cancer-Related Pain

This study compared the efficacy of a tetrahydrocannabinol:cannabidiol (THC:CBD) extract, a nonopioid analgesic endocannabinoid system modulator, and a THC extract, with placebo, in relieving pain in patients with advanced cancer. In total, 177 patients with cancer pain, who experienced inadequate analgesia despite chronic opioid dosing, entered a two-week, multicenter, double-blind, randomized, placebo-controlled, parallel-group trial. Patients were randomized to THC:CBD extract (n = 60), THC extract (n = 58), or placebo (n = 59). The primary analysis of change from baseline in mean pain Numerical Rating Scale (NRS) score was statistically significantly in favor of THC:CBD compared with placebo (improvement of -1.37 vs. -0.69), whereas the THC group showed a nonsignificant change (-1.01 vs. -0.69). Twice as many patients taking THC:CBD showed a reduction of more than 30% from baseline pain NRS score when compared with placebo (23 [43%] vs. 12 [21%]). The associated odds ratio was statistically significant, whereas the number of THC group responders was similar to placebo (12 [23%] vs. 12 [21%]) and did not reach statistical significance. There was no change from baseline in median dose of opioid background medication or mean number of doses of breakthrough medication across treatment groups. No significant group differences were found in the NRS sleep quality or nausea scores or the pain control assessment. However, the results from the European Organisation for Research and Treatment of Cancer Quality of Life Cancer Questionnaire showed a worsening in nausea and vomiting with THC:CBD compared with placebo (P = 0.02), whereas THC had no difference (P = 1.0). Most drug-related adverse events were mild/moderate in severity. This study shows that THC:CBD extract is efficacious for relief of pain in patients with advanced cancer pain not fully relieved by strong opioids.

Incidence, prevalence, and predictors of chemotherapy-induced peripheral neuropathy: A systematic review and meta-analysis

ABSTRACT Chemotherapy‐induced peripheral neuropathy (CIPN) is a disabling pain condition resulting from chemotherapy for cancer. Severe acute CIPN may require chemotherapy dose reduction or cessation. There is no effective CIPN prevention strategy; treatment of established chronic CIPN is limited, and the prevalence of CIPN is not known. Here we used a systematic review to identify studies reporting the prevalence of CIPN. We searched Embase, Medline, CAB Abstracts, CINAHL, PubMed central, Cochrane Library, and Web of Knowledge for relevant references and used random‐effects meta‐regression to estimate overall prevalence. We assessed study quality using the CONSORT and STROBE guidelines, and we report findings according to Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidance. We provide a qualitative summary of factors reported to alter the risk of CIPN. We included 31 studies with data from 4179 patients in our analysis. CIPN prevalence was 68.1% (57.7–78.4) when measured in the first month after chemotherapy, 60.0% (36.4–81.6) at 3 months and 30.0% (6.4–53.5) at 6 months or more. Different chemotherapy drugs were associated with differences in CIPN prevalence, and there was some evidence of publication bias. Genetic risk factors were reported in 4 studies. Clinical risk factors, identified in 4 of 31 studies, included neuropathy at baseline, smoking, abnormal creatinine clearance, and specific sensory changes during chemotherapy. Although CIPN prevalence decreases with time, at 6 months 30% of patients continue to suffer from CIPN. Routine CIPN surveillance during post‐chemotherapy follow‐up is needed. A number of genetic and clinical risk factors were identified that require further study.

Emotional distress in cancer patients: the Edinburgh Cancer Centre symptom study.

To: (1) estimate the prevalence of clinically significant emotional distress in patients attending a cancer outpatient department and (2) determine the associations between distress and demographic and clinical variables, we conducted a survey of outpatients attending selected clinics of a regional cancer centre in Edinburgh, UK. Patients completed the Hospital Anxiety and Depression Scale (HADS) on touch-screen computers and the scores were linked to clinical variables on the hospital database. Nearly one quarter of the cancer outpatients 674 out of 3071 (22%; 95% confidence interval (CI) 20–23%) met our criterion for clinically significant emotional distress (total HADS score 15 or more). Univariate analysis identified the following statistically significant associations: age <65, female gender, cancer type and extent of disease. Multivariate analysis indicated that age <65 (odds ratio 1.41; 95% CI 1.18–1.69), female gender (odds ratio 1.58; 95% CI 1.31–1.92) and active disease (odds ratio 1.72; 95% CI 1.43–2.05) but not cancer diagnosis, were the independent predictors of clinically significant emotional distress. Services to treat distress in cancer patients should be organised to target patients by characteristics other than their cancer diagnosis.

Nabiximols for Opioid-Treated Cancer Patients With Poorly-Controlled Chronic Pain: A Randomized, Placebo-Controlled, Graded-Dose Trial

UNLABELLED Patients with advanced cancer who have pain that responds poorly to opioid therapy pose a clinical challenge. Nabiximols (Nabiximols is the U.S. Adopted Name [USAN] for Sativex [GW Pharma Ltd, Wiltshire, U.K.], which does not yet have an INN), a novel cannabinoid formulation, is undergoing investigation as add-on therapy for this population. In a randomized, double-blind, placebo-controlled, graded-dose study, patients with advanced cancer and opioid-refractory pain received placebo or nabiximols at a low dose (1-4 sprays/day), medium dose (6-10 sprays/day), or high dose (11-16 sprays/day). Average pain, worst pain and sleep disruption were measured daily during 5 weeks of treatment; other questionnaires measured quality of life and mood. A total of 360 patients were randomized; 263 completed. There were no baseline differences across groups. The 30% responder rate primary analysis was not significant for nabiximols versus placebo (overall P = .59). A secondary continuous responder analysis of average daily pain from baseline to end of study demonstrated that the proportion of patients reporting analgesia was greater for nabiximols than placebo overall (P = .035), and specifically in the low-dose (P = .008) and medium-dose (P = .039) groups. In the low-dose group, results were similar for mean average pain (P = .006), mean worst pain (P = .011), and mean sleep disruption (P = .003). Other questionnaires showed no significant group differences. Adverse events were dose-related and only the high-dose group compared unfavorably with placebo. This study supports the efficacy and safety of nabiximols at the 2 lower-dose levels and provides important dose information for future trials. PERSPECTIVE Nabiximols, a novel cannabinoid formulation, may be a useful add-on analgesic for patients with opioid-refractory cancer pain. A randomized, double-blind, placebo-controlled, graded-dose study demonstrated efficacy and safety at low and medium doses.

Prevalence and natural history of pain in adults with multiple sclerosis: Systematic review and meta-analysis

The prevalence, associations, and natural history of pain in multiple sclerosis (MS) are poorly understood. The objective of this work was to study the prevalence of pain syndromes in MS both cross‐sectionally, and longitudinally during the MS disease course. We systematically identified prospective studies detailing pain prevalence in definite MS. We used pooled prevalence estimates, explored heterogeneity using meta‐regression, and analysed prevalence during the disease course using both estimates at disease milestones and longitudinal studies. Twenty‐eight articles (7101 subjects) describing overall pain, or pain syndromes, met inclusion criteria. Pooled overall pain prevalence (17 studies, 5319 subjects) was 63% (95% confidence interval [CI] 55–70%). Marked heterogeneity in this estimate was not significantly explained by selected study design variables (use of outpatient sample, timeframe prior to study over which pain was assessed) or sample demographic variables (mean Expanded Disability Status Scale, mean disease duration, proportion of female sex, and proportion with progressive MS). We quantified prevalence of headache (43%; 95% CI 33–52%), neuropathic extremity pain (26%; 95% CI 7–53%), back pain (20%; 95% CI 13–28%), painful spasms (15%; 95% CI 8.5–23%), Lhermitte sign (16%; 95% CI 10–25%), and trigeminal neuralgia (3.8%; 95% CI 2–6%) in included studies. Prevalence of pain at MS disease milestones (prior to onset, at onset, and at relapse) and during longitudinal follow‐up was poorly described. Pain is common in MS, as are specific pain syndromes. The clinical associations and natural history of pain in MS require clarification. Future study could be enhanced by standardised study design.

Neuropathic pain in cancer.

Cancer-related neuropathic pain is common; it can be disease related or related to the acute or chronic effects of cancer treatment. For example, chemotherapy-induced peripheral neuropathy occurs in 90% of patients receiving neurotoxic chemotherapy. Cancer treatments have become more effective; patients are living longer with cancer and there are more cancer survivors. However, side-effects (particularly neuropathy) have become more problematic. The key to management of cancer-related neuropathy is a considered assessment, remembering not to miss the opportunity of reversing the cause of the pain with appropriate oncological management. An increasing range of oncological therapies are available, including radiotherapy, chemotherapy, hormonal therapy, or one of the evolving approaches (e.g. immune therapies). Patients are often elderly and with comorbidities; therefore, all treatment decisions have to be made carefully and reviewed appropriately. Cancer pain is often of mixed aetiology or, if purely neuropathic, may be one of several pains experienced by a patient. For these reasons, opioids are used more frequently in patients with cancer-related neuropathic pain. Standard guidelines for the use of anticonvulsants (e.g. pregabalin and gabapentin), antidepressants (e.g. duloxetine and tricyclics), and topical treatments (e.g. capsaicin and lidocaine) may be applicable, but there is a lack of good-quality clinical trials in cancer-related neuropathic pain. Choice is dictated not just by age, drug interactions, and comorbidities, but also by the coexistence of many symptoms in patients with cancer. Treating more than one symptom with a particular neuropathic pain agent can avoid polypharmacy.

Pain, depression, and fatigue as a symptom cluster in advanced cancer.

CONTEXT Pain, depression, and fatigue are common symptoms in cancer populations. They often coexist and have been suggested as a specific symptom cluster. Systemic inflammation (SI) may be a possible common mechanism. OBJECTIVE This study examined whether pain, depression, and fatigue exist as a symptom cluster in advanced cancer patients with cachexia and might be related to the presence of SI. METHODS Secondary data analysis was undertaken of two clinical trials in patients with cancer cachexia (n = 654). Pain, depression, and fatigue were assessed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-C30. Plasma C-reactive protein (CRP) was measured as a marker of SI in a subgroup (n = 436). Multivariate analysis and a series of regression analyses were undertaken relating pain, depression, fatigue, and CRP. RESULTS Pain, depression, and fatigue clustered, with between two and four times as many patients having all three symptoms as would be expected if the symptoms only coexist by chance (P < 0.001). CRP was not related to the symptom cluster. There was a strong relationship between the pattern of symptoms and physical functioning (P < 0.001). CONCLUSION Pain, depression, and fatigue is an identifiable symptom cluster in a cohort of cachexic cancer patients and is associated with reduced physical functioning.

Challenges in cancer pain management – bone pain

Whilst not strictly a neuropathic injury, cancer-induced bone pain (CIBP) is a unique state with features of neuropathy and inflammation. Recent work has demonstrated that osteoclasts damage peripheral nerves (peptidergic C fibres and SNS) within trabeculated bone leading to deafferentation. In addition, glia cell activation and neuronal hyperexcitability within the dorsal horn, are all similar to a neuropathy. Gabapentin and carbamazepine (both anti-convulsants that modulate neuropathy) are effective at attenuating dorsal horn neuronal excitability and normalizing pain-like behaviours in a rat model of CIBP. However alterations in neuroreceptors in the dorsal horn do not mimic neuropathy, rather only dynorphin is upregulated, glia cells are active and hypertrophic and c-fos expression is increased post-noxious behavioural stimulus. CIBP perhaps illustrates best the complexity of cancer pains. Rarely are they purely neuropathic, inflammatory, ischaemic or visceral but rather a combination. Management is multimodal with radiotherapy, analgesics (opioids, NSAIDs), bisphosphonates, radioisotopes and tumouricidal therapies. The difficulty with opioids relates to efficacy on spontaneous pain at rest and movement-related pain. Potential adjuvants to standard analgesic therapies for CIBP are being explored in clinical trials and include inhibitors of glutamate release.

Translational medicine: cancer pain mechanisms and management

Cancer-induced bone pain (CIBP) is a major clinical problem with up to 85% of patients with bony metastases having pain, often associated with anxiety and depression, reduced performance status, and a poor quality of life. Malignant bone disease creates a chronic pain state through sensitization and synaptic plasticity within the spinal cord that amplifies nociceptive signals and their transmission to the brain. Fifty per cent of patients are expected to gain adequate analgesia from palliative radiotherapy within 4-6 weeks of treatment. Opioid analgesia does make a useful contribution to the management of CIBP, especially in terms of suppressing tonic background pain. However, CIBP remains a clinical challenge because the spontaneous and movement-related components are more difficult to treat with opioids and commonly used analgesic drugs, without unacceptable side-effects. Recently developed laboratory models of CIBP, which show congruency with the clinical syndrome, are contributing to an improved understanding of the neurobiology of CIBP. This chronic pain syndrome appears to be unique and distinct from other chronic pain states, such as inflammatory or neuropathic pain. This has clear implications for treatment and development of future therapies. A translational medicine approach, using a highly iterative process between the clinic and the laboratory, may allow improved understanding of the underlying mechanisms of CIBP to be rapidly translated into real clinical benefits in terms of improved pain management.