Cancer Pain ManagementAdvancing towards optimal symptom management
The University of Texas MD Anderson Cancer Center, USA
With improved treatments for cardiovascular and infectious diseases, life expectancy is increasing. For this reason and environmental factors, the incidence and prevalence of cancer is rising worldwide. Pain and overall symptom burden remains problematic for cancer patients. Unrelieved pain leads to increased morbidity through multiple mechanisms: decrease in functional status... read morewith increased sedentary related complications such as deep venous thrombosis and pneumonia; depression, anxiety, and an associated lack of compliance with recommended treatments, including in some cases the inability to complete treatment protocols, and other adverse sequela. Studies show around 30 % of ambulatory cancer patients suffering moderate to severe pain. With progressive disease, the incidence is far higher. Breakthrough pain or episodic severe pain is often quite problematic for cancer patients.
Cancer pain stems from the tumor itself in most cases. Tumors cause pain due to invasion of bone, soft tissues, muscle and nervous structures. In some cases, rapid tumor growth or lysis is very painful. A less frequent cause of cancer pain is treatment related pain-including post chemotherapy neuropathic pain, post-surgical pain syndromes and post-radiation pain syndromes. A thorough examination to determine the etiology of the pain will assist in its successful management. The molecular basis for this nociception is currently being elucidated and may lead to more focused therapies in the future.
Pain can be further classified into the broad categories of nociceptive versus neuropathic pain. Nociceptive pain may be either somatic or visceral in origin. Some common examples of nociceptive somatic pain include bone metastasis and vertebral compression fractures. Classic nociceptive visceral pain includes pancreatic cancer pain. Neuropathic pain is seen with chemotherapy induced painful peripheral neuropathies, post-herpetic neuralgias, phantom limb pain, and others. Nociceptive pain syndromes are typically opioid responsive, whereas in neuropathic pain states adjuvant analgesics may be needed to obtain adequate analgesia.
In some patients, opioid doses are limited by intolerable side effects including sedation, confusion, constipation, nausea, and pruritis. These side effects are best managed with changing opioids, adding agents to treat the side effect, or using neuraxial, neural blockade, or other interventional pain techniques to lower systemic opioids doses
Some basic tenets of cancer pain management include the use of:
• Oral opioids whenever possible
• Combinations of long acting opioids for constant pain with short acting opioids for “breakthrough” pain
• Adjuvant co-analgesics including NSAIDS, anticonvulsants, antidepressants, and topicals to minimize opioid doses and concomitant opioid related side effects
• Prophylactic treatment of constipation and nausea
• Interventional options for pain control including: nerve blocks, parenteral infusions, neuraxial infusions, palliative XRT, palliative chemo and surgery in combination for optimal patient quality of life (the “art” of oncology)
In most cases, adequate pain and symptom control can be obtained through regular assessment and application of the relatively straightforward principles outlined above.