Pain control in thoracic oncology

A thoracic surgeon's perspective (G. Massard)

The best that a surgeon can offer in order to reduce postoperative pain is to decrease operative trauma [10]. For this patient with presumably a cT1bN0 lung cancer, according to the American College of Chest Physicians (ACCP) guidelines for treatment of lung cancer, there is an obvious advantage to offering a video-assisted thoracoscopic surgery (VATS) approach with a grade II evidence [11]. The latter allows for an adequate cancer operation combining an anatomical resection (i.e. lobectomy) with a formal hilar and mediastinal node dissection, while incisions are reduced to stab wounds and use of a rib retractor is not required.

Several large data studies, including two systematic reviews [12, 13], two database studies from the USA and Europe [14, 15] and two meta-analyses [16, 17], concluded that VATS offers an advantage over thoracotomy in terms of significantly reducing complication rates, shortening hospital stay and enhancing recovery. The authors assume that reduced operative trauma and consequently reduced pain are the determining factors. A recently published randomised controlled trial by Bendixen et al. [18] which enrolled 206 patients confirms this assumption. Pain and self-reported quality of life during the first postoperative year were compared between the two groups, defined either by a four-port VATS approach or an anterolateral thoracotomy. The study demonstrated a statistically significant decrease in pain and an improved self-reported quality of life at different time points for up to 1 year in patients undergoing VATS versus anterolateral thoracotomy. The lower complication rate is confirmed in patients with disabled pulmonary function [19].

All these publications converge to the statement that VATS is a better surgical procedure for early-stage disease, and hence it appears unethical to proceed with an open thoracotomy. However, many colleagues remain reluctant to apply minimally invasive techniques; we may estimate from the French database Epithor that only 30% of eligible patients are operated by VATS (unpublished data).

A first series of questions concerns the oncologic value of minimally invasive procedures. These seem to be unfounded, because both anatomical resection and lymph node dissection can be safely and accurately performed [20, 21]. These assumptions have been swept away by two meta-analyses concluding similar overall long-term survival and disease-free survival [22]. In addition, a non-randomised study demonstrated that compliance to adjuvant chemotherapy is significantly improved with a VATS approach [23].

The second reason might be reluctance on the part of experienced consultant surgeons to change working habits and to learn a new technique, which still has the reputation of being complicated and subject to risk of intra-operative complications. However, there is evidence for a relatively short learning curve for experienced surgeons. The author's experience demonstrates that competence (i.e. confirmed oncologic quality) is acquired after 30 procedures, and efficacy (i.e. decreased operating time, conversion rate and air leak) after 90 procedures [24]. Simulation training may shorten the learning curve [25]. Surgical trainees may be directly oriented towards minimally invasive technique without extensive experience in open surgery [26], and VATS should be taught in any accredited training programme.

Which are the options for future development? There is currently a strong interest, supported by industry, in developing single-incision VATS; however, it remains controversial whether reducing the number of incisions will improve the immediate outcome, or might be deleterious for long-term survival [27]. The effects of market pressure can also be seen as medical centres strive to begin to offer robotically assisted VATS. For the moment, it appears that robot assistance does not improve outcomes, but increases operation time and cost [28]. However, the market is open to competition and the financial conditions may change. With improving technology, perhaps the future might be single-incision robotic surgery?

A pain specialist's perspective (C. Peeters-Asdourian)

Both thoracotomy and video-assisted minimally invasive anatomical resections may be associated with post-thoracotomy pain syndrome, though VATS is associated with less morbidity and a decreased incidence of persistent post-surgical pain syndrome. Overall, when following major surgical procedures, the incidence of persistent pain ranges from 20% to 50% 2 months after surgery [29].

Predictive factors for post-thoracotomy pain include moderate-to-severe perioperative pain, younger age (adults), preoperative anxiety and depression, female sex, radiation therapy to the area, neurotoxic chemotherapy and psychological vulnerability. Genetic predisposition as a result of functional polymorphism of catechol-O-methyltransferase (COMT) may also contribute to chronic pain [30].

The severity of acute postoperative pain may be the most relevant factor contributing to a persistent pain syndrome following surgery [31, 32].

Adequate pain control following thoracotomy and/or VATS includes a multimodal analgesic approach combining thoracic epidural analgesia usually between T4 and T8, provided that there are no pre-existing contraindications such as coagulopathy or sepsis, or paravertebral blocks with NSAIDs and other medications. Regional anaesthesia techniques have been shown to decrease the incidence and severity of post-thoracotomy pain. Paravertebral blocks with or without catheter placement and serratus blocks are an alternative to epidural analgesia and can be performed using ultrasound guidance.

Minimally invasive surgical techniques have also contributed to reducing long-term morbidity, as described above.

Non-opioid analgesics can also play an adjuvant role. These can include NSAIDS, N-methyl-D-aspartate (NMDA)-receptor antagonists, i.e. ketamine, alpha-2 agonists such as dexmedetomidine, and the alpha-2-delta subunit ligands of the voltage-gated calcium channels gabapentin and pregabalin. Use of these medications is limited by both patient tolerance and the presence of medical or surgical contraindication [33].

A pain specialist's perspective (M. Almalki)

A Pancoast tumour is defined by the ACCP [34] as: “a lung cancer arising in the apex of the lung that involves structures of the apical chest wall. Invasion of apical chest wall structures is required at the level of the first rib or above, but it is not necessary to have Horner syndrome or pain radiating down the arm. These lesions frequently invade the brachial plexus, subclavian vessels, or spine” [35].

Shoulder pain is usually the first and most common presentation owing to extension of the tumour to the extra-thoracic structures. As the tumour proliferates, patients can often develop paraesthesia and weakness along the ulnar nerve distribution. This occurs secondary to tumour invasion of the inferior aspect of the brachial plexus C8-T1 and can, in some cases, extend into the T2 territory (the axilla and medial aspect of the upper arm) as well. These musculoskeletal symptoms may delay the work-up and diagnosis [36]. As the tumour invades the sympathetic chain, a Horner's syndrome may develop in 15–50% of patients [37, 38]. In approximately 5% of patients, spinal cord compression can occur as the tumour spreads into the intervertebral foramina early in the course of disease [39].

The tumour can be seen on chest radiographs as a mass in the apex of the lung or as a pleural thickening. It is important to remember that it can be easily missed on the chest radiograph. A CT scan can confirm the location and the extension of the tumour.

An MRI should be obtained, as well, to better evaluate the extension of the tumour to the surrounding structures, including the brachial plexus, cervical plexus, neural foramen, vertebral body and adjacent vasculature.

Malignant, inflammatory, autoimmune and neuropathic processes of the tumour in the lung, pleura and brachial and cervical plexus can lead to different types of pain. Neuropathic pain is likely the primary aetiology of the pain associated with a Pancoast tumour due to its close proximity to both the cervical and brachial plexus. Neuropathic pain is usually described as burning”, “shock-like” or as an “electrical sensation”. It may be associated with allodynia (i.e. pain induced by non-painful stimuli), hyperalgesia (i.e. increased perception of painful stimuli) and other concomitant neurological findings, such as weakness or changes in reflexes, and autonomic dysfunction [40]. The prevalence of neuropathic pain is about 20% to 40% of all cancer pain [41]. Its higher incidence in Pancoast tumour pain is likely due to the reasons detailed above.

Pain control is an important factor in the management of every patient with a Pancoast tumour: through a multidisciplinary approach including radiotherapy, chemotherapy, surgical resection if feasible, pain medications and interventional pain procedures as indicated. The pain is often resistant to opioids alone and will require adjuvant neuropathic pain agents such as antidepressants and gabapentinoids.

Tricyclic antidepressants (amitriptyline, nortriptyline), serotonin-norepinephrine reuptake inhibitors (duloxetine, venlafaxine), and calcium-channel modulators (gabapentin and pregabalin) are the most frequently utilised neuropathic pain medications in the management of neuropathic cancer pain [42]. Topical therapies such as lidocaine patch, diclofenac patch, or compound creams containing a variety of medications ranging from local anaesthetics, neuropathic agents, muscle relaxants, and agents from clonidine to amantadine can also be trialled. Application of a capsaicin patch or ointment which is available in a range of concentrations, typically between 0.025% and 0.075%, can be trialled as well, though it should not be applied to any open skin or wounds [42].

If the pain is resistant to oral medications, an alternative drug delivery route or neuroablative procedure may be necessary. An intrathecal drug delivery system may be considered depending on the patient's life expectancy and prognosis; typically, patients are required to have a 3- to 6-month life expectancy prior to considering implant. A programmable intrathecal pump delivering morphine or hydromorphone as single agents, or in combination with clonidine, bupivacaine and/or ziconotide for their analgesic properties in the management of neuropathic pain, can be used [43].

Less invasive therapies, including stellate ganglion block or neurolysis, intercostal nerve block or neurolysis, and paravertebral blocks, can be considered and tailored to the individual patient depending on the location of pain and extension of the tumour. In cases of brachial plexus involvement, a single-shot ultrasound-guided brachial plexus injection using a combination of local anaesthetic and steroid can serve both a diagnostic and a therapeutic role. Placement of indwelling catheter or neurolysis may provide longer term pain relief [44].

Neuroablative procedures at the level of the dorsal route ganglion may constitute a very effective, well-tolerated and minimally invasive therapy. Such procedures are usually performed under fluoroscopic, CT or MRI guidance using radiofrequency ablative techniques. Cryotherapy can also be helpful (table 2) [45].

A radiation therapist's perspective (P. Van Houtte)

This is an interesting clinical case of superior sulcus tumour with a Pancoast tumour, which is probably not a candidate for a radical trimodality (surgery, radiotherapy, chemotherapy) approach owing to the tumour extent, especially the nodal involvement. N1 involvement would still allow for a reasonable postoperative outcome in a trimodality setting, especially in a low comorbidity context. Extension to the vertebral body or subclavian artery is not an absolute contraindication to a radical R0 resection per se.

One key question is how to define the best treatment approach for palliation but also aim for long-term loco-regional control of the disease. Radiation is a very effective treatment regarding pain management owing to bone involvement by tumour, with an early response rate above 60% including pain reduction and even a complete clearance of symptoms. In a series from our service dating back to more than 20 years, pain relief was achieved in 21 out of 28 treated patients [46].

This can be achieved with a short course of radiation (less than 2 weeks) with minimal side effect. It is a purely palliative approach without any aims at controlling the disease and with the risk of recurrence of pain later on, probably within the first year.

To sustain the pain control, which can only be achieved through loco-regional control of the disease, a higher radiation dose is needed to control the tumour while trying to avoid radiation injuries to the brachial plexus and the spinal cord. Currently, for locally advanced lung cancer, including such a superior sulcus tumour, the best approach is certainly to combine chemotherapy and radiotherapy by adding a cisplatin-based chemotherapy with a definitively high radiation dose above 60 Gy. The data clearly show an improved survival, due mainly to a better loco-regional control. This range of dose requires a high and precise radiation technology to cover the tumour, including the vertebral involvement and the positive nodes, without damaging the spinal cord. This may be achieved using an intensity-modulated radiotherapy combined with precise imaging at the linear accelerator to verify the correct positioning of the patient and delivery of the radiation. Such a treatment is more aggressive and takes 6–7 weeks. It may induce oesophagitis, the main acute side effect. Currently, different reports have demonstrated the feasibility of such an approach for superior sulcus tumour, leading to pain control and even long-term survival [47, 48].

A pain specialist's perspective (C. Peeters-Asdourian)

Bony metastases occur frequently in lung cancer, accounting for a large number of vertebral lesions. These vertebral metastases are associated with pain and morbidity. They have a significant impact on the patient's quality of life and can cause severe breakthrough pain with physical activity. Additionally, pathologic fractures can result in spinal cord compression.

Bone-targeted agents (BTAs) are an important part of the management of bony metastases. These include inhibitors of osteoclastogenesis and osteoclast activation and receptor activator factor kappa-B ligand (RANKL) inhibitors such as bisphosphonates and denosumab respectively. ESMO, NCCN and the American Society of Clinical Oncology support the use of BTAs in patients with breast cancer, prostate cancer and multiple myeloma to prevent and delay skeletal complications and pain. In lung cancer patients, the data shows some benefit in reducing skeletal-related events and bone pain, but further studies are needed to explore the impact of these agents on survival. Both bisphosphonates and denosumab are associated with complications including jaw osteonecrosis, hypocalcaemia and infections, which are more frequent with denosumab [49].

In addition to offering opioids and adjuvant medications such as NSAIDS, and gabapentin or pregabalin as tolerated, the pain specialist may offer less invasive treatment options than spine surgery.

Radiofrequency spinal tumour ablation (RFA) can be considered as it is safe and effective for well-selected patients. RFA can be performed with and without cement [50].

Cryoablation techniques have been used as well and may be safer in terms of risks for spinal complications.

Vertebral augmentation procedures, vertebroplasty and kyphoplasty, can certainly be considered. All of these techniques require imaging guidance, fluoroscopy or computed tomography (CT scans). These procedures are minimally invasive and are performed under conscious sedation or monitored anaesthesia care, but in some cases, may require a general anaesthethic.

Exclusion for these approaches includes posterior extension of the tumour into the spinal canal, bone fragment extension into the spinal canal or retropulsion, and spinal instability [51]. Various specialists can perform these procedures: interventional radiologists, spine surgeons or interventional pain specialists, depending on the country.

Pulsed radiofrequency of the dorsal root ganglion (DRG) can be used successfully for intractable vertebral metastatic pain. Radiofrequency has been effective in the management of neuropathic pain syndromes and will help in cases where a radiculopathy is a part of the pain presentation.

Contraindications are the same as for all the minimally invasive techniques and include coagulopathy and sepsis [45].

A spine surgeon's perspective (A.P. White)

This 55-year-old woman with lung adenocarcinoma had previously undergone chemo- and radiotherapies to address (in part) L1 and L2 vertebral lesions. 1 year later, back pain prompted imaging re-evaluation. Marrow-replacing lesions were found within the vertebral bodies of L1 and L4. The L1 lesion encroached upon the epidural space.

Patients with metastatic epidural spine lesions can benefit from surgical management when certain aspects of the spine anatomy become compromised [52]. When there is significant axial pain related to spine instability, and when the integrity of the neurological elements has been compromised (or may become compromised), surgery can be considered. Surgical decompression and stabilisation has been shown to reduce pain, to prolong the ability to walk, and to preserve bowel and bladder continence for patients with epidural metastasis.

The benefit of surgery is not applicable to all patients. One of the most relevant considerations is the overall prognosis of the patient [53]. If the patient were expected to survive for less than 6 months, many surgeons would not consider the short-term morbidity of the surgery (including short-term postoperative pain) to be worth the proposed benefit of longer-term pain relief and neurological preservation. For this reason, patients with longer-term survival expectations should be considered to be better candidates for surgery.

In this particular case, if the patient were expected to survive for 6 months or more, surgery would be considered to be helpful. The images indicate that there is significant compromise of the integrity of the L1 vertebrae. There is epidural involvement with stenosis. The risk of vertebral collapse will increase over time. The consequence of that may be significant, including lower extremity paraplegia with bowel and bladder incontinence. Surgery can effectively reduce that risk, and can also reduce pain associated with the instability, particularly in the long term.

Surgical decompression and stabilisation can be accomplished by a variety of approaches, each with its own risks and benefits [54, 55]. In patients with metastatic disease, the spinal reconstruction should be immediately robust. Overall, this patient population has a high risk of non-union following spinal fusion; the implanted hardware comprising the spinal reconstruction should be expected to remain intact and robust for the duration of the patient's life. One cannot rely on bone fusion or healing to provide additional stability. For these reasons, in part, spinal reconstructions for many patients (including this one) may involve combined anterior and posterior surgery.

Independent of the benefits of pain reduction, preservation of mobility, and preservation of continence, spine surgery should not be expected to prolong the life of the patient with metastatic disease. It can, however, be expected to improve comfort, maintain independence and preserve dignity for patients while they navigate the other aspects of this difficult disease.

A pain medicine specialist's perspective (C. Peeters-Asdourian and P.H. Rana)

This case illustrates the need for collaboration with the palliative care team for optimal analgesic management, with the thoracic oncologist for possible optional palliative chemotherapy and radiation therapy, and with the pain medicine specialist for consideration of the spinal route of opioid administration or other advanced interventional therapies. These interventions may be needed in 5%–15% of cancer patients who are in advanced or terminal stages of their disease [56]. Aetiology of pain in complex cancer patients is multifactorial, and the presence of pleural nodular thickening may contribute to the development of pleural effusion and visceral pain, which can be particularly challenging to manage.

The oral route (p.o.) is the preferred route in most cancer patients. However, a recent study shows, as expected, with our improved knowledge of pharmacokinetics, pharmacodynamics and pharmacogenetics, that patients may have varying responses to different medications, impacting their effectiveness as a treatment modality.

The CYP2D6 isoenzyme of the cytochrome P450-system is highly polymorphic.

Because of variations in the alleles of CYP2D6, about 10% of the Caucasian population is categorised as poor metabolisers and about 4–5% as ultra-rapid responders. These differences may account for the lack of effect in some patients and adverse drug reactions in others.

Poor metabolisers may not respond to codeine and not fully to tramadol [57].

Hepatic and renal function may have an impact on the drug efficacy, side-effects and toxicity. The addition of adjuvant drugs may create drug interactions that will modify the response to treatment as well (table 3).

One recent study demonstrated that terminal cancer patients may not be receiving strong opioids in a timely manner. The intravenous route should be considered, and in many cases preferred, when swift titration is required. The peak effect occurs more rapidly after approximately 15 min, as compared with a p.o. or subcutaneous route, which may take up to 30 min and is less reliable. Intravenous administration needs to be considered when absorption of the medication is suboptima, for example, in a patient with persistent pain receiving p.o. morphine sulphate immediate-release (MSIR) and with a short gut. Allowing the patient to self-titrate with a patient-controlled analgesia device can also be very helpful.

Intrathecal administration of opioids, local anaesthetics, clonidine (alpha-2 agonist) and ziconotide (N-type calcium channel blocker) as needed for neuropathic pain can be realised using an intrathecal catheter and an internalised pump which is both programmable and refillable. This approach requires a team with the appropriate expertise and a support team which, after implant, will be able to follow the patient, to adjust the regimen, refill the pump and programme it [55]. Contraindications include failed trial of intrathecal administration of analgesic, and systemic infection, while relative contraindications are coagulopathy, immunosuppression, poor support, and life expectancy. The EAPC has published evidence-based recommendations [7].

Pain due to chest wall invasion or rib metastases can be treated by intercostal neurolysis or DRG radiofrequency ablation or neurolysis [45]. Once again, specialised providers and support staff will be needed, as well as equipment, fluoroscopy or a CT scan for needle guidance, and an RFA machine, for the provision of these therapeutic modalities. In the USA and throughout the world, as restrictions on its use and decriminalisation take hold, many patients and caregivers enquire about the use of Cannabis sativa, more commonly known as marijuana, for the management of a multitude of cancer-related symptoms including pain, particularly at end of life.

Cannabinoid binds as agonists, antagonists or inverse agonists at the classical G protein-coupled CB1 and CB2 receptors, as well as at a multitude of non-cannabinoid receptors such as transient receptor potential vanilloid (TRPV). Cannabidiol (CBD), first isolated in 1963, has in animal models been shown to have an anti-emetic, analgesic and anti-inflammatory effect without displaying overt psychomimetic properties, making it attractive as a therapeutic agent [58, 59]. Whiting et al. [60] published a large systematic review involving 79 randomised trials and 6462 patients, a minority of whom were cancer patients; overall, the average number of patients who reported at least 30% improvement in pain was greater with cannabinoids than with placebo. Two recent trials involving the use of nabiximol, an oromucosal spray containing 2.7 mg of tetrahydrocannabinol (THC) and 2.5 mg CBD per 100 mL, in cancer patients with poorly controlled pain had mixed results. Johnson et al. (2010) noted a statistically significant improvement in NRS (Numerical Rating Scale) pain score in favour of CBD/THC versus placebo (improvement −1.37 versus −0.69) [61]. In a more recent study published in 2012, a continuous responder analysis demonstrated that the number of patients reporting analgesia was greater in the CBD group than in the placebo group (p=0.35); however, it failed to reach the primary outcome of 30% reduction in pain severity [62]. Overall, there is thought to be moderate evidence to support the use of cannabinoids as an adjuvant agent in the management of opioid refractory active cancer pain, though its use remains contentious and further investigation is required (table 4).

A chest physician's perspective (B. Grigoriu)

Pain, fatigue, cough and dyspnoea are the main symptoms experienced by patients with advanced intrathoracic tumours [63]. Mesothelioma patients are more prone to experiencing difficult-to-manage pain and dyspnoea owing to the local progression of the disease. In addition, this particular patient had bone metastases. Progressive tissue invasion generates pain that may be difficult to control with analgesics alone. A systematic review of chemotherapy trials showed that a minority of trials report symptom control, but in those that do, it has been shown that pain and dyspnoea may be improved by chemotherapy despite low response rates and variable effect on survival [64]. Modern treatments involving a new generation of antifolate and a platinum derivative significantly improve survival over platinum alone, but surprisingly, published data show no difference in any component of quality of life (which includes pain) [65]. However, old and less effective regimens such as MVP (methotrexate, vincristine, cisplatin) [66] or vinorelbine monotherapy [67] may improve symptoms in more than half of the patients. A feasibility study of active symptom control (ASC) alone or associated with chemotherapy (MVP regimen or vinorelbine alone) showed that this approach may be used for palliation of pain and possibly dyspnoea, leading to a doubling of the percentage of patients experiencing improvement compared to ASC alone [68]. A retrospective English cohort showed that two-thirds of patients experienced symptom improvement during chemotherapy [69]. However, a clinical improvement was noted in only one-third of patients receiving cisplatin, doxorubicin and mitomycin in an older Italian Phase II trial [70]. A three-arm randomised trial comparing ASC either alone or with MVP or vinorelbine showed no significant difference in symptom control (global physical functioning, pain, dyspnoea and global quality of life) in patients receiving chemotherapy despite the fact that in the first 3 months chemotherapy seems to generate a decrease in moderate and severe chest pain [71].

Dyspnoea is almost invariably present in mesothelioma and may be related to both tumour development and pleural fluid accumulation. Indwelling pleural catheters (IPCs) offer an option as they allow for convenient pleural fluid removal [72]. A randomised trial showed that IPCs offer the same level of improvement as pleurodesis, but the trial is not specific to mesothelioma [73, 74]. The diffuse nature of mesothelioma infiltration renders lung expansion difficult, so direct pleurodesis is rarely possible in advanced cases. Thus, the use of IPCs is a convenient option for dyspnoea management.

A palliative care specialist's perspective (D. Lossignol)

Pain is a major problem in cancer as it occurs in 30–50% patients in earlier stages and in 70–90% of these patients with advanced disease and is often associated with other symptoms (dyspnoea, gastrointestinal tract disorders, neurological syndromes, etc.) [75].

The three-step framework for cancer-related pain management was published for the first time in 1986. Step I recommends non-opioid analgesics (NSAIDs, paracetamol) for mild pain. Step II specifies the use of weak opioids for moderate pain (codeine, tramadol). Step III comprises the use of strong opioids for severe pain (morphine, methadone, fentanyl, hydromorphone).

To achieve better pain relief, an appropriate application of adjuvant analgesics (i.e. for neuropathic pain), supportive drugs (for the prevention and treatment of opioid adverse effects), and non-pharmacological measures such as radiotherapy and invasive procedures (nerve blockades and neurolytic blocks) should be considered and applied [76].

There is a growing recognition of the importance of the psychological impact of pain on cancer patients, regardless of the type of cancer, especially as the number of cancer survivors increases. Psychological factors can exert an important influence across a range of pain-related behaviour, treatment outcomes, and social and familial activities [77–80].

Dyspnoea due to pleural effusion, lymphangitis or bronchial obstruction remains a challenge at the end of life, especially because the patient will not benefit from intensive care and invasive procedures.

Non-invasive ventilation offers an option but remains unusual in palliative care because it remains difficult to identify patients who will benefit from this technique, and this option remains controversial in patients who have elected specific limits to life support [81, 82]. Thoracocentesis, chemical or talc pleurodesis, and minimally invasive palliative treatment options such as chronic IPCs may all be helpful in cases of pleural effusion. Steroids are proposed in cases of pulmonary lymphangitis. The effect on dyspnoea is short in duration because of progressive disease. Intercostal muscle atrophy is of concern, especially in debilitated or cachectic patients. Nebulised or parenteral morphine may be helpful, but its effectiveness is controversial [83].

Continuous sedation is a therapeutic option that makes it possible to relieve a patient from unbearable suffering related to refractory symptoms [84–86].

A symptom is considered refractory when the clinician believes that interventions, invasive or not, will no longer provide adequate relief, that their use will produce intolerable or excessive morbidity, or that it is not possible to hope for relief in an acceptable period of time. The suffering that occurs is considered to be intolerable by the patient. These terms obviously have subjective value and must be interpreted within a closely monitored medical context. The decision to put a patient into a state of irreversible unconsciousness is not without ethical consequence, and it is essential to have a clearer view of the practice of sedation [87]. The essential role of the palliative care specialist is to alleviate the burden of suffering and to do more good than harm in respect of the patient's expectations.