Antitumor and antinociceptive approaches to control cancer pain

CT-guided pain procedures for intractable pain in malignancy

CT-guided stereotactic percutaneous destructive procedures, i.e. percutaneous cordotomy, trigeminal tractotomy, and extralemniscal myelotomy, have been routinely used for the treatment of localized intractable pain in malignancy since 1987. In 67 cases if local pain due to malignancy, CT guided percutaneous cordotomy was performed and in 97% complete pain control was achieved. In 45 of these cases, a "selective cordotomy" was performed meaning that analgesia was produced only in the painful region of the body. CT guided trigeminal tractotomy was applied to a total of 19 cases in 5 of which pain had been caused by malignancy. The results were satisfactory. 12 cases, suffering from visceral pain due to malignancy, were treated by CT-guided extralemniscal myelotomy and in 10 cases pain relief was achieved.

Cancer pain management. Current strategy

Pain is among the most prevalent symptoms experienced by cancer patients. A strategy for the management of cancer pain is now widely accepted, and when well implemented, is usually effective. Unfortunately, many oncologists are ill-prepared for the task of pain assessment and management, and the outcomes achieved in clinical practice are often suboptimal. The various elements in the pain management strategy are described. Patient assessment, the use of primary therapies and systemically administered nonopioid and opioid analgesics are pivotal to the strategy. Practical aspects of opioid pharmacotherapy encompass drug selection and dosing considerations including selection of an appropriate route of administration, dose titration, and the management of side effects. Specific approaches are described for the treatment of patients for whom an acceptable balance between relief and side effects of opioids is not achieved. These comprise noninvasive interventions, including the use of adjuvant analgesics, psychological therapies, and physiatric techniques, and invasive interventions, such as the use of intraspinal opioids, neural blockade, and neuroablative techniques. Finally, the use of sedation in the treatment of patients with pain that is refractory to other interventions is addressed. The skilled application of this strategy can provide adequate relief to the vast majority of patients, most of whom will respond to systemic pharmacotherapy alone. Patients with refractory pain should see specialists in pain management or palliative medicine who can address these difficult problems.

On the putative uniqueness of cancer pain: do psychological principles apply?

A large volume of evidence has supported the important role of psychological principles and variables related to the perception of, and response to, nociceptive stimulation. On the basis of this research, a number of psychological interventions have been developed and used successfully with pain patients. Despite the evidence, there has been a tendency for practitioners to neglect the contributing role of cognitive, affective, and behavioral factors in reports of pain by cancer patients. Cancer seems to hold a unique status in medicine and society at large. In this paper, the cancer pain literature is briefly reviewed and evidence is presented for various psychological determinants of the pain report and response that may be extended to pain associated with cancer. The implications of these data for understanding and treatment of cancer patients are described.

Neurosurgery in the treatment of cancer pain

Patients with pain syndromes resulting from recurrent or metastatic cancer should be evaluated carefully to determine the cause of their pain and the need for appropriate antitumor treatment. Currently, opioid analgesics are the mainstay of pain control, but side effects limit their use in some patients. When pharmacologic pain control is inadequate or associated with intolerable side effects, neurosurgery should be considered. Currently the implantation of a pump for the intraspinal infusion of opioid analgesics is the most popular procedure, but its usefulness may be limited by the development of opioid tolerance. The most effective ablative pain control procedure at the current time is cordotomy, which is indicated in patients with unilateral pain. Although the place of neurostimulatory procedures in controlling cancer pain is not well established, they are attractive because of their nondestructive nature and potential usefulness in the treatment of bilateral pain syndromes. Specific antitumor surgical procedures should be considered in patients with certain spinal and plexopathy syndromes, because such intervention offers the prospect of both pain relief and tumor control. In this article, the neurosurgical procedures used in the management of cancer pain are reviewed.

Integration of pain management into comprehensive cancer care

Pain management is an integral component of comprehensive cancer care. Designing an effective pain control strategy for the individual patient requires knowledge of the ways in which a patient's cancer, cancer therapy, and pain therapy can interact. Two important aspects of cancer that affect the way in which pain is managed are the cancer's treatability and components of its pathophysiology that themselves do not cause pain (the cancer's "nonpain" pathophysiology). Cancer treatability modifies the need for pain management and the appropriateness of invasive pain procedures. Cancer nonpain pathophysiology can interfere with the oral administration of medications, narrow the patient's therapeutic window for analgesic drugs, limit the effectiveness of psychologic pain therapies, and complicate or preclude invasive pain-relieving procedures. In addition, cancer therapy can interfere with or enhance pain therapy and vice versa. Cancer therapy can interfere with pain therapy by causing pain or by producing other adverse effects. Cancer therapy can enhance pain therapy by reducing the extent of cancer, by acting as a coanalgesic, and by providing intravenous access for parenteral drug administration to patients who require it. Pain therapy can interfere with cancer therapy by increasing or complicating the adverse effects of cancer therapy. Pain therapy can enhance cancer therapy by improving patient performance, and certain palliative surgical procedures may have the ancillary effect of improving organ function. Five case descriptions are presented as illustrations of effective integration of pain management into comprehensive cancer care.

Diagnosis and treatment of cancer in aged animals

Considerable morbidity can be associated with cancer and the diagnosis and treatment of cancer. Knowledge of a tumor's likely clinical behavior and an awareness of the benefits and morbidity associated with treatment will help the clinician and the owner find the most appropriate plan of action for the aged pet with cancer. Tumor cell heterogeneity is a concept of enormous importance in our understanding of neoplasia. Phenotypic variations within cancer cell populations often confound our attempts to cure a patient's cancer. Frequently, we are forced to settle for palliative therapy when our patient's cancer has advanced beyond our ability to rescue.