Opioid Analgesia in Aged Cancer Patients

In this issue of ONCOLOGY, Marvin Omar Delgado-Guay and Eduardo Bruera give a comprehensive overview of cancer pain management in the elderly. Their article briefly addresses the prevalence and pathophysiology of pain in older patients, assessment of pain and distress in the elderly (including cognitively impaired patients), and pharmacologic and interdisciplinary pain management strategies in this population.

Public Health Issue

Cancer pain management in the elderly is truly a public health and quality-of-care issue. Most of the cancer patients and cancer survivors are 65 years old or older. The median age of the 1.5 million new cancer patients diagnosed in the United States in 2007 was 67 years (for all sites combined).[1] Approximately 60% of the estimated 10.8 million cancer survivors in the US today are older than 65 years.[2] Nevertheless, age appears to be one of the barriers to the delivery of the quality cancer care including pain management.

Studies have demonstrated that the presence of comorbid health conditions and perceived health vulnerability of elderly cancer patients can lead to undertreatment of the elderly, with resulting poor prognoses.[3] In a recently published large population study, late or unstaged cancer was diagnosed in 62% of 1,907 elderly Medicaid-insured nursing home residents. With only 28% of patients having access to hospice care, mortality within 3 months of diagnosis was seen in 48%. Only 22% patients in this study received cancer-directed surgery, and only 6% of patients received chemotherapy and/or radiation. Patients aged 71 to 75 years were twice as likely to have cancer-directed surgery than patients aged 86 years and older. It is striking that other demographic characteristics and comorbid conditions had little predictive value with regard to cancer treatment or hospice use in nursing home patients.[4]

Opioid Dosing in the Elderly

How to approach opioid analgesia in the elderly remains a controversy.[5-8] It has been suggested that elderly cancer patients may require lower doses of opioid medication to achieve the same analgesia as younger adults.[9,10] In other studies, a slight increase in the pain threshold in elderly adults was associated with moderate to substantial decreases in pain tolerance.[11-13] Zhen et al reported that topical application of capsaicin produced a longer-lasting mechanical hyperalgesia among older subjects.[14] Similarly, an enhanced temporal summation and reduced habituation to repetitive thermal stimulation was shown in experimental pain in elderly patients.[15]

Washington et al examined the effects of repeated immersion of the hand in cold water on thermal and electrical pain thresholds in samples of young and elderly volunteers.[16] The results of the study indicated that the increase in thresholds during the postimmersion period was significantly greater among younger subjects, suggesting potential age-related decrements in pain-modulatory capacity. Accumulated evidence, therefore, indicates that endogenous analgesic mechanisms decline in the elderly, increasing their susceptibility to pain.[17]

In a recent large clinical study of 100 cancer patients, Mercadante et al evaluated the differences in opioid titration between younger (< 65) and older (75 and over) patients. Pain intensity, dose of opioids, need for opioid rotation, routes of administration, and opioid-related symptoms were measured from admission until dose stabilization. Despite differences in opioid doses at admission (lower in older patients), no differences were found between younger and older patients in terms of daily opioid dose increase, routes, need to switch, or other parameters. Similarly, adverse effects did not significantly differ between the groups, although an overall distress score worsened in older patients during acute titration and then improved at stabilization time. These data contradict the assumption that older patients are more susceptible than younger adults to side effects during opioid titration.[18]

Barriers to Pain Control

The assumption that older patients require a lower amount of opioid analgesia than younger adults (and that older patients are more likely to be affected by opioid-related side effects) may lead to undertreatment of elderly patients with cancer pain. The attitudes, beliefs, and preferences of patients and their families may be influencing treatment choices as well.[19] Elderly patients may be reluctant to report uncontrolled pain because they fear caregiver burnout, which may lead to their institutionalization. Elderly patients may also be concerned about the sedating side effects of analgesic medications, wary of the potential for falls, injuries, and a resulting loss of independence.

Concerns of the caregivers may become an additional barrier to appropriate cancer pain management. In Australia, approximately 75% of the caregivers demonstrated concerns about addiction, a belief likely to affect the use of prescribed opioids in the home.[20] It is essential to get to know the individual caregiver's views on pain and analgesia. Adult children, who are the dominant caregivers for disabled women, and wives, who are the dominant caregivers for disabled men,[21] regulate the frail patient's access to analgesic medications. Caregiver education as well as routine screening for caregiver burnout and patient abuse may improve patient access to analgesics and overall analgesia.

Conclusions

Of the two-thirds of cancer patients who experience pain during the course of their illness, the majority will require opioid analgesics for appropriate pain control. Considering comorbid conditions, opioids in the elderly need to be titrated up cautiously but aggressively in accordance with National Comprehensive Cancer Network and American Pain Society guidelines.[22,23] Careful titration based on the individual response seems appropriate irrespective of age. An analgesic regimen should be tailored to the patient's needs and based on the preferred route of administration, degree of tolerance for opioids, medical condition, and previous experience with opioids. Age should not prevent appropriate treatment of cancer or cancer-associated pain in older individuals.

Financial Disclosure:The author has no significant financial interest or other relationship with the manufacturers of any products or providers of any service mentioned in this article.

References:

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23. American Pain Society: Principles of Analgesic Use in the Treatment of Acute Pain and Cancer Pain, 5th ed. Glenview, Illinois, American Pain Society, 2007.