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Cancer is frequently associated with a host of distressing physical and psychosocial symptoms that can occur throughout the disease trajectory (1). Access to a multidisciplinary supportive care service is imperative for patients with cancer experiencing distressing symptoms, including fatigue, pain, anorexia, nausea, dyspnea, anxiety, depression, and weight loss, to improve the quality of life of patients. Without optimal symptom control, administration of anticancer therapies may be delayed or discontinued (Table 58-1).
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Uncontrolled pain has been reported by 42% of patients seen in the outpatient cancer center (1) and 50% of hospitalized patients with cancer (2). Pain was the most common symptom (82%) among patients with cancer referred to a palliative care service (3). In patients with cancer, pain may be the only symptom present prior to diagnosis and can indicate the recurrence or spread of the disease.
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As many as 30% to 50% of patients receiving active anticancer therapy experience pain (1). Pain resulting from the tumor burden occurs in approximately 65% to 85% of patients with advanced cancer (4). In addition, treatment-related pain is reported by approximately 15% to 25% of patients, and 3%-10% of patients with cancer develop chronic nonmalignant pain syndromes similar to the general population (eg, low back pain associated with degenerative disk disease).
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The pathophysiologic classification of pain forms the basis for therapeutic choices. Pain may be broadly divided into those associated with ongoing tissue damage (nociceptive) and those resulting from nervous system dysfunction (neuropathic). Nociceptive pain can be classified as either somatic or visceral and results from the activation of nociceptors in cutaneous or deep tissues. Nociceptive pain is described by patients as localized aching, throbbing, and gnawing discomfort. Visceral pain is the result of activation of nociceptors resulting from distention, stretching, and inflammation of internal organs. It is often poorly localized discomfort, described as a deep aching or cramping or a pressure-like sensation. An example of visceral pain is abdominal pain due to pancreatic cancer. Breakthrough pain is defined as a transitory exacerbation of discomfort that occurs on a background of stable persistent chronic pain. Causes of breakthrough pain include end-of-dose failure of opioids and pain exacerbation by activity or spontaneous occurrence. Breakthrough pain is also characterized by a short duration, often less than 3 minutes in 43% of cases according to previous prospective surveys (...