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Chronic cancer pain management: Current controversies in treatment
254
Chronic cancer pain management:
current controversies
in treatment.
Kathleen M. Foley, M.D.
Cornell University Medical College, New York, NY 1002 1 The evaluation and treatment of pain in patients with cancer has now evolved to encompass a series of clinical guidelines which define a comprehensive approach to the management of this difficult medical problem. Current knowledge in cancer pain includes the description of the common cancer pain syndromes in this population as well as their postulated neurophysiologic mechanisms; the classification of the types of patients with pain, the different types of pain (acute, chronic, breakthrough) and the psychological factors that contribute to and alter the pain complaint; the development and implementation of well validated pain measurement methodologies to assess pain intensity, degree of relief and mood (psychological distress); the modeling of pharmacokinetic/pharmacodynamic relationships to correlate opioid drug distribution with pain relief and side effects; and refined use of anesthetic and neurosurgical approaches and the broader integration of cognitive behavioral approaches. These advances have focused attention on the cancer patient as the clinical model of pain and have led to improved pain management of patients with medical illness. This patient population has offered the unique opportunity as a natural experiment to study the chronic administration of analgesic drugs, specifically the opioids, to non-addict populations, providing insight as well as controversy in their appropriate use for different types of pain and the phenomenon of clinical tolerance, and physical and psychological dependence. Data from the World Health Organization Cancer and Palliative Care Unit reports that 4.3 million cancer patients die each year with inadequate control of cancer pain. To remedy the situation the WHO has created a Cancer Pain Relief Program and through a series of experts panels has developed guidelines for the treatment of cancer pain. The program has achieved a broad international consensus based on the concept that analgesic drug therapy is the mainstay of treatment for the majority of patients with cancer pain. Field testing of the WHO Guidelines, in conjunction with clinical experience, has shown that SO-90% of cancer patients’pain can be controlled using a simple, inexpensive method described as the Three Step Analgesic Ladder. This approach is based on the use of a combination of non-opioid, opioid, and adjuvant drugs titrated to the individual needs of the patient, according to the severity of pain and its pathophysiology. Implementation of the analgesic guidelines, assurance of drug availability--specifically opioids; the education of health care professionals, and designating cancer pain a priority for all national cancer control programs are the major goals of the WHO effort. A series of controversies in the clinical use of opioids in cancer pain have evolved. The major controversial issues influencing the use of pharmacologic approaches include the role of opioids in the management of neuropathic pain. It has been suggested that neuropathic pain, which accounts for 1O20% of difficult to manage pain problems, is “opioid resistant” and that opioid drugs are ineffective and should not be used. From studies in cancer patients with both nociceptive and neuropathic pain as well as from controlled studies in non-malignant neuropatbic pain syndromes, neuropathic pain demonstrates a variable response. Patient characteristics, pain related factors, as well as drug selective effects influence this variable responsiveness. Controlled studies assessing the efficacy of opioids and adjuvant drugs in various cancer pain syndromes are critical to resolve the controversy and to provide scientifically based guidelines for neuropathic pain.
25s
A second controversy is the choice of opioid drug. New information on the pharmacology of morphine, coupled with. increasing information on the pharmacodynamics and pharmacokinetics of methadone, hydromorphone, fentanyl, levorphanol, and oxycodone have helped to clarify the observation that there is no “best” opioid drug. Individualized therapy is the critical factor to ensure effective analgesia and numerous other opioid drugs can be used to manage cancer pain. A third controversy includes the route of administration. Although the oral route represents the simplest and most commonly used approach, the impetus for the development of these novel routes of administration has come from the goal to maximize analgesia, minimize side effects and provide convenient dosing schedules for patients who require parenteral drug administration. Survey data demonstrate that the majority of patients with progressive disease and pain will require at least two, and in at least 25% of cases, three routes of drug administration. What remains controversial is the logic of both patient selection and timing and implementation of these alternative routes. Another controversy that is critical is the issue of the development of tolerance. From a series of studies assessing the patterns of opioid drug use in cancer pain patients, it is evident that the role of tolerance development various enormously among patients and is influenced by numerous environmental, behavioral and pharmacologic pain and patient-related factors. Tolerance develops at different rates to each of the opioid effects. Cross-tolerance is incomplete. There are currently multiple ways to provide analgesia to patients who are tolerant to opioid analgesics. Lastly, the most pressing controversy is the confusion on the part of health care professionals about pain management in the dying patient. It is the responsibility of the treating physician to manage pain in this patient population. The intent, goal, and conditions in which physicians and patients interact are directed toward the management of symptoms and should not be construed as euthanasia. Aggressive treatment of pain with increasing doses of opioids to provide analgesia should not be referred to as “hastening death”. Its intent and rationale are to manage uncontrollable or unendurable symptoms. The lack of understanding of the concept of tolerance, the dearth of pharmacologic data on drugs to provide terminal sedation, and the ambivalence on the part of patients, families, and physicians because of ethical concerns have thwarted the provision of appropriate medical care for the population of patients. Any debate that focuses on the needs of the dying patient and their options for care at the end of life must recognize that the education and training of physicians as well as patients and families is the first step in providing patients with access to care that will facilitate their choice of options.
References: 1.
2. 3. 4. 5.
Foley KM: N Engl J Med 31384-95, 1985. Foley KM: Cancer 63~2257-2266, 1989. Portenoy RK et al: Pain 43 ~273-286, 1990. Foley KM: In: Basbaum AI et al (eds) Toward a New Pharmacotherapy of Pain. Dahlem Conferenzen, Chicester: John Wiley & Sons Ltd., 18 l-204, 199 1. Foley KM: In: Chapman CR et al (eds) Current & Emerging Issues in Cancer Pain: Research & Practice, New York, Raven Press, 33 l-349, 1993.
Chronic cancer pain management:
current controversies
in treatment.
Kathleen M. Foley, M.D.
Cornell University Medical College, New York, NY 1002 1 The evaluation and treatment of pain in patients with cancer has now evolved to encompass a series of clinical guidelines which define a comprehensive approach to the management of this difficult medical problem. Current knowledge in cancer pain includes the description of the common cancer pain syndromes in this population as well as their postulated neurophysiologic mechanisms; the classification of the types of patients with pain, the different types of pain (acute, chronic, breakthrough) and the psychological factors that contribute to and alter the pain complaint; the development and implementation of well validated pain measurement methodologies to assess pain intensity, degree of relief and mood (psychological distress); the modeling of pharmacokinetic/pharmacodynamic relationships to correlate opioid drug distribution with pain relief and side effects; and refined use of anesthetic and neurosurgical approaches and the broader integration of cognitive behavioral approaches. These advances have focused attention on the cancer patient as the clinical model of pain and have led to improved pain management of patients with medical illness. This patient population has offered the unique opportunity as a natural experiment to study the chronic administration of analgesic drugs, specifically the opioids, to non-addict populations, providing insight as well as controversy in their appropriate use for different types of pain and the phenomenon of clinical tolerance, and physical and psychological dependence. Data from the World Health Organization Cancer and Palliative Care Unit reports that 4.3 million cancer patients die each year with inadequate control of cancer pain. To remedy the situation the WHO has created a Cancer Pain Relief Program and through a series of experts panels has developed guidelines for the treatment of cancer pain. The program has achieved a broad international consensus based on the concept that analgesic drug therapy is the mainstay of treatment for the majority of patients with cancer pain. Field testing of the WHO Guidelines, in conjunction with clinical experience, has shown that SO-90% of cancer patients’pain can be controlled using a simple, inexpensive method described as the Three Step Analgesic Ladder. This approach is based on the use of a combination of non-opioid, opioid, and adjuvant drugs titrated to the individual needs of the patient, according to the severity of pain and its pathophysiology. Implementation of the analgesic guidelines, assurance of drug availability--specifically opioids; the education of health care professionals, and designating cancer pain a priority for all national cancer control programs are the major goals of the WHO effort. A series of controversies in the clinical use of opioids in cancer pain have evolved. The major controversial issues influencing the use of pharmacologic approaches include the role of opioids in the management of neuropathic pain. It has been suggested that neuropathic pain, which accounts for 1O20% of difficult to manage pain problems, is “opioid resistant” and that opioid drugs are ineffective and should not be used. From studies in cancer patients with both nociceptive and neuropathic pain as well as from controlled studies in non-malignant neuropatbic pain syndromes, neuropathic pain demonstrates a variable response. Patient characteristics, pain related factors, as well as drug selective effects influence this variable responsiveness. Controlled studies assessing the efficacy of opioids and adjuvant drugs in various cancer pain syndromes are critical to resolve the controversy and to provide scientifically based guidelines for neuropathic pain.
25s
A second controversy is the choice of opioid drug. New information on the pharmacology of morphine, coupled with. increasing information on the pharmacodynamics and pharmacokinetics of methadone, hydromorphone, fentanyl, levorphanol, and oxycodone have helped to clarify the observation that there is no “best” opioid drug. Individualized therapy is the critical factor to ensure effective analgesia and numerous other opioid drugs can be used to manage cancer pain. A third controversy includes the route of administration. Although the oral route represents the simplest and most commonly used approach, the impetus for the development of these novel routes of administration has come from the goal to maximize analgesia, minimize side effects and provide convenient dosing schedules for patients who require parenteral drug administration. Survey data demonstrate that the majority of patients with progressive disease and pain will require at least two, and in at least 25% of cases, three routes of drug administration. What remains controversial is the logic of both patient selection and timing and implementation of these alternative routes. Another controversy that is critical is the issue of the development of tolerance. From a series of studies assessing the patterns of opioid drug use in cancer pain patients, it is evident that the role of tolerance development various enormously among patients and is influenced by numerous environmental, behavioral and pharmacologic pain and patient-related factors. Tolerance develops at different rates to each of the opioid effects. Cross-tolerance is incomplete. There are currently multiple ways to provide analgesia to patients who are tolerant to opioid analgesics. Lastly, the most pressing controversy is the confusion on the part of health care professionals about pain management in the dying patient. It is the responsibility of the treating physician to manage pain in this patient population. The intent, goal, and conditions in which physicians and patients interact are directed toward the management of symptoms and should not be construed as euthanasia. Aggressive treatment of pain with increasing doses of opioids to provide analgesia should not be referred to as “hastening death”. Its intent and rationale are to manage uncontrollable or unendurable symptoms. The lack of understanding of the concept of tolerance, the dearth of pharmacologic data on drugs to provide terminal sedation, and the ambivalence on the part of patients, families, and physicians because of ethical concerns have thwarted the provision of appropriate medical care for the population of patients. Any debate that focuses on the needs of the dying patient and their options for care at the end of life must recognize that the education and training of physicians as well as patients and families is the first step in providing patients with access to care that will facilitate their choice of options.
References: 1.
2. 3. 4. 5.
Foley KM: N Engl J Med 31384-95, 1985. Foley KM: Cancer 63~2257-2266, 1989. Portenoy RK et al: Pain 43 ~273-286, 1990. Foley KM: In: Basbaum AI et al (eds) Toward a New Pharmacotherapy of Pain. Dahlem Conferenzen, Chicester: John Wiley & Sons Ltd., 18 l-204, 199 1. Foley KM: In: Chapman CR et al (eds) Current & Emerging Issues in Cancer Pain: Research & Practice, New York, Raven Press, 33 l-349, 1993.