The management of cancer pain

Any therapeutic strategy developed for patients experiencing cancer pain depends on the goals of care, which can be broadly categorized as prolonging survival, optimizing comfort, and optimizing function. The relative priority of these goals for any individual should direct therapeutic decision-making. By combining primary treatments, systemic analgesic agents, and other techniques, most cancer patients can achieve satisfactory relief of pain. In cases where pain appears refractory to these interventions, invasive anesthetic or neurosurgical maneuvers may be necessary, and sedation may be offered to those with unrelieved pain at the end of life. The principles of analgesic therapy are presented, as well as the practical issues involved in drug administration, ranging from calculating dosage to adverse effects, and, when necessary, how to switch and/or combine therapies. Adjuvant analgesics, which are drugs indicated for purposes other than relief of pain but which may have analgesic effects, are also listed and discussed in some detail. Surgical and neurodestructive techniques, such as rhizotomy or cordotomy, although not frequently required or performed, represent yet other options for patients with unremitting pain and diminished hope of relief. Although cancer pain can be a complex medical problem arising from multiple sources, patients should be assured that suffering is not inevitable and that relief is attainable.     

The pharmacologic management of cancer pain

The management of cancer pain requires familiarity with a range of therapeutic strategies, including antineoplastic therapies, analgesic pharmacotherapy, and anesthetic, neurosurgical, psychological, and rehabilitation techniques. Successful pain management is characterized by implementation of the techniques with the most favorable therapeutic index for the prevailing circumstances, along with provision for repeated evaluations, so that a favorable balance between pain relief and adverse effects is maintained. For most patients, pain management involves the administration of specific analgesic approaches. In all cases, these analgesic treatments must be skillfully integrated with the management of other symptoms.     

Pharmacological management of cancer pain

Given modern techniques of pain assessment and management, it is now possible to be optimistic about cancer pain control. Assessment of cancer pain must include information about the site(s) of pain, pathophysiology, pain severity, and quantification of analgesic responses. Correct diagnosis of common pain patterns including breakthrough and incident pain are essential. The principles of analgesic use are well defined. The concept of rescue dosing in safe analgesic titration and management of breakthrough/incident pain is a key concept. Individualization of opioid dosing is important and this is facilitated by a number of dosing strategies. Choice of specific opioid is often less important than correct dosing, as side effects are similar among the commonly prescribed drugs. Anticipations and management of common side effects improve the therapeutic index. Alternate routes of administration are important, usually because of loss of the oral route of administration. Misunderstandings about opioids are common and patient and family education paramount. Adjuvant analgesics are necessary for good pain control, but have important differences in indications, usage, and side effects compared with opioids. First-rate pain management is a basic professional and humanitarian responsibility of the skilled clinical oncologist.     

Anesthetic management of cancer pain

Diagnostic and therapeutic nerve blocks are potent tools that can be utilized as one component of the armamentarium in the overall management of cancer pain. With the advent of the multidisciplinary approach to cancer pain management, the appropriate role of nerve blocks should be examined in terms of timing and risk-benefit ratio for each individual patient. Improved patient selection, prior utilization of other lower risk techniques, improved understanding of patient goals, and changes in pain experience may result in higher success. The ultimate goal is to provide comfort without sacrificing other functions important to the patient and/or family.     

Advances in cancer pain management

Although most patients with cancer pain can attain a favorable balance between analgesia and side effects with a conventional approach to opioid therapy, a substantial minority cannot. For these patients, an important subgroup of whom have neuropathic pain, alternative therapeutic strategies are needed. With a detailed assessment, clinicians should be able to choose among the large and diverse group of options available and implement an approach, or combination of approaches, that have a high probability of improving analgesic outcomes.     

Advances in cancer pain management

Control of malignant pain and related symptoms is paramount to clinical success in caring for cancer patients. To achieve the best quality of life for patients and families, oncologists and palliative care clinicians must work together to understand problems related to psychologic, social, and spiritual pain. Pain is the primary problem targeted for control using the World Health Organization’s (WHO) analgesic ladder. This article focuses on increased knowledge of analgesic action that may enable expansion of the WHO analgesic ladder to fulfill the broader objectives of palliative medicine. We discuss clinical experience with several classes of drugs that are currently used to treat cancer pain: 1) nonsteroidal anti-inflammatory drugs (NSAIDs), with emphasis on cyclooxygenase-2 (COX-2) inhibitors; 2) opioid analgesics, with specific emphasis on methadone and its newly recognized value in cancer pain; 3) ketamine, an antagonist at N-methyl D-aspartate (NMDA) receptors; and 4) bisphosphonates, used for pain resulting from bone metastases. New concepts that compare molecular actions of morphine at excitatory opioid receptors, and methadone at non-opioid receptor systems, are presented to underscore the importance of balancing central nervous system excitatory (anti-analgesic) versus inhibitory (analgesic) influences.     

癌痛管理相关进展及全球差异性

在全球范围内,癌痛仍然是一个重要的临床问题。癌症引发疼痛的机制复杂、多种多样。伴随癌痛的生物学进展,越来越多的人认为癌痛是肿瘤细胞与宿主免疫、周围神经系统与中枢神经系统之间的交叉效应所致的结果。癌痛管理是控制疼痛、提高病人生活质量的不可或缺的治疗手段,癌痛治疗的选择也应根据不同个体量身定制。阿片类药物仍然是治疗癌痛最有效的药物,而神经调节作为治疗神经性癌痛的新兴技术也发展迅速。当前,全球范围内镇痛药物的可用性存在差异,中低收入国家明显低于高收入国家。在未来的几十年,全球癌症负担将逐年加重,因此提高全社会的癌痛管理意识迫在眉睫。     

Interventional techniques for cancer pain management

Patients with cancer frequently experience pain, and even with increased modern knowledge and skills in drug and other therapy, this pain is poorly controlled in a significant proportion. For these patients, a range of interventional techniques can play a significant role in providing pain relief. These include neuraxial administration of opioids and other drugs, temporary or permanent blockade of nerve pathways and minimally invasive management of bony and other metastases. Those involved in the treatment of pain from cancer should be aware of the scope of these techniques and ready to call upon specialists in their use.     

Adjuvant analgesics in cancer pain management

Adjuvant analgesics are defined as drugs with a primary indication other than pain that have analgesic properties in some painful conditions. The group includes numerous drugs in diverse classes. Although the widespread use of these drugs as first-line agents in chronic nonmalignant pain syndromes suggests that the term "adjuvant" is a misnomer, they usually are combined with a less-than-satisfactory opioid regimen when administered for cancer pain. Some adjuvant analgesics are useful in several painful conditions and are described as multipurpose adjuvant analgesics (antidepressants, corticosteroids, alpha(2)-adrenergic agonists, neuroleptics), whereas others are specific for neuropathic pain (anticonvulsants, local anesthetics, N-methyl-D-aspartate receptor antagonists), bone pain (calcitonin, bisphosphonates, radiopharmaceuticals), musculoskeletal pain (muscle relaxants), or pain from bowel obstruction (octreotide, anticholinergics). This article reviews the evidence supporting the use of each class of adjuvant analgesic for the treatment of pain in cancer patients and provides a comprehensive outline of dosing recommendations, side effects, and drug interactions.     

Improving cancer pain management in Malaysia

Within Malaysia's otherwise highly accessible public healthcare system, palliative medicine is still an underdeveloped discipline. Government surveys have shown that opioid consumption in Malaysia is dramatically lower than the global average, indicating a failure to meet the need for adequate pain control in terminally ill patients. Indeed, based on daily defined doses, only 24% of patients suffering from cancer pain receive regular opioid analgesia. The main barriers to effective pain control in Malaysia relate to physicians' and patients' attitudes towards the use of opioids. In one survey of physicians, 46% felt they lacked knowledge to manage patients with severe cancer pain, and 64% feared effects such as respiratory depression. Fear of addiction is common amongst patients, as is confusion regarding the legality of opioids. Additional barriers include the fact that no training in palliative care is given to medical students, and that smaller clinics often lack facilities to prepare and stock cheap oral morphine. A number of initiatives aim to improve the situation, including the establishment of palliative care departments in hospitals and implementation of post-graduate training programmes. Campaigns to raise public awareness are expected to increase patient demand for adequate cancer pain relief as part of good care.