Paradigm Shift in Cancer Pain Management
In spite of the reported high success rate in its management, national and international health organizations (e.g., World Health Organization) have concluded that cancer pain remains under-reported and under-treated. In patients with a potentially life-threatening disease, pain can add greatly to the debilitating effects of the disease, foster hopelessness and fear, and reduce the ability of the patient to comply with interventions directed at the disease itself. Generally, current treatment approaches work from a biomedical model to manage carcinoma-related pain in patients with early-staged disease. When pain presents in advanced disease and/or persists, treatment only then involves an interdisciplinary approach within a biopsychosocial context. The present paper reviews the current application of an interdisciplinary model in cancer pain management and explores the lessons that we can learn from other pain populations.
In 2002, the American Society of Clinical Oncology’s (ASCO) strategic plan listed interdisciplinary collaborations in the prevention, management, and research of the wide trajectory of cancer as its main priority. To date, bits and pieces of this commitment can be seen in many areas of cancer; however, such collaborations appear to be lacking in cancer pain management. Indeed, the application of an interdisciplinary model to address pain in an oncology population ranges from being entirely absent to being in the early stages of infancy compared to non-cancer pain populations.1 This is not necessarily unexpected. Recent large-scale reviews have concluded that 90% of cancer pain in patients with early-staged disease can be effectively managed by simple medical interventions.2,3 In spite of these impressive rates, many health organizations have recently described the current treatment paradigm in addressing malignant pain as suboptimal.3-6 The complex nature of cancer and the cascade of physical and emotional consequences that accompany the disease may contribute to the under-estimation of cancer pain and/or lead to its chronicity.
Until recently, interdisciplinary approaches for non-cancer pain patients were reserved for those with more chronic, treatment-reticent pain. However, a burgeoning body of empiricism has begun to show that such approaches during the acute stage (three months or less) of pain may help prevent it from persisting.7-10 In terms of cancer pain, there is a relative paucity of data on the benefits of introducing interdisciplinary strategies to relieve pain in cancer patients with early-staged disease. Using musculoskeletal pain as a backdrop, this paper considers the current strategies in cancer pain management within an interdisciplinary, biopsychosocial context. As such, we pose the following question: Is a shift in paradigm needed in cancer pain management? Central to this paper will be the review of: (1) the current strategies for treating malignant pain; (2) the research supporting the application of an interdisciplinary model in musculoskeletal pain during the acute phase; and (3) the rationale and barriers to an interdisciplinary approach in addressing pain in patients with early-staged disease.
Definition and Epidemiology of Cancer Pain
Historically, both research and clinical realms have differentiated pain populations by classifying their pain as either malignant or non-malignant, the former referring to pain associated with a fatal (or potentially fatal) disease and the latter referring to pain without such disease. These labels were predicated upon the premise that only malignant pain was to be treated with opioids. Although dated, this distinction somewhat lingers, in that each pain population undergoes different treatment approaches. Treatment for chronic, non-malignant pain patients often involves a tertiary level of care bearing an interdisciplinary approach within a biopsychosocial context. Perhaps we view this population as having a more complex pain presentation and history than malignant pain. In turn, we recommend treatment approaches that recognize and appreciate this complexity. Alternatively, we view patients with pain related to a carcinoma as having an unremarkable pain history with symptoms that can be managed adequately by the treating physician—with anticipation that palliative care services will oversee cases of advanced disease with complicated pain.
However, we must consider several criteria in addressing cancer pain. First, the disease site often determines whether the need for pain management will arise. Certain types of cancer, as a function of location, are more painful than other types. The pain site not only suggests the presence of a tumor, but also provides a point of reference as to the difficulty in relieving the symptoms. In addition, the stage of disease also influences the risk for cancer pain, in which pain issues may only manifest in advanced-staged disease (e.g., pain resulting from tumor penetration of tissue). Alternatively, cancer pain may not stem from the malignancy itself but, instead, as a product of cancer treatment. Finally, it would be erroneous to assume that all pain reports from cancer patients relate to their carcinoma. Collectively, these issues underscore the importance of a comprehensive assessment to guide treatment planning and delivery.
Health care providers estimate that many cancer patients will experience disease- or treatment-related pain at a level of severity that will warrant clinical intervention.11-15 Approximately 1/3 of cancer patients undergoing active therapy, and 3/4 of cancer patients with advanced disease are estimated to suffer from a clinical level of pain.16,17 It is reported that the prevalence of chronic pain is about 30-50% among cancer patients during the active phase of treatment for a solid tumor. Direct tumor involvement represents the most common cause of cancer pain (approximately 85% of patients on inpatient pain services, and up to 65% of patients in outpatient pain clinics.18 The second most common type of cancer pain involves tumor infiltration of the nerve, followed by tumor infiltration of the hollow viscus (see Table 1). Even with well-controlled pain, approximately 2/3 of cancer patients experience breakthrough pain. The increased awareness of this symptom likely provided the impetus in the recent development of treatment guidelines for oncology populations, many of which, as will be discussed, advocate for an interdisciplinary approach.