Cancer pain management





A 57-year-old man presented to the pain management specialist complaining of epigastric pain radiating to the back. His sclerae were mildly icteric. Magnetic resonance imaging (MRI) showed a mass at the head of the pancreas.




1


What is the incidence of cancer pain?


The number of new cases of cancer in the United States is almost 2 million per year. Of these, approximately 50% of patients with intermediate-stage cancers and 75% of patients with advanced-stage cancers have pain. The incidence of cancer pain is approximately 1 million cases per year.




2


What is the prevalence of cancer pain by organ system?


Different organ systems are variably associated with cancer pain. Pancreatic cancer is the most common type of cancer associated with pain. Bone cancer is the second most common malignancy producing pain. Both cancers cause pain in >80% of cases. Breast, lung, and colon cancers are associated with pain in >70% of cases. Lymphomas and leukemias produce pain in about 60% of patients.




3


What are the different causes of pain in patients with cancer?


There are multiple causes of cancer pain. In approximately 65% of cases, pain is caused by direct invasion, involvement of nerves or the neuraxis, obstruction of a viscus, or metastasis to distant tissues. Anticancer treatments are responsible for 25% of cancer pain. Treatment-related pain is due to surgery, diagnostic procedures, chemotherapy side effects, and radiation complications. Syndromes unrelated to cancer cause 10% of pain in oncology patients. Patients with cancer may also have common non–cancer-related pain syndromes, such as lower back pain and headaches.




4


What is the who ladder?


The World Health Organization (WHO) devised a protocol ( Box 72-1 ) for treating pain using a tiered approach. This protocol allows for the use of less potent medications initially (first tier), followed by increasingly more potent medications (second and third tiers) which are added in a stepwise approach until the patient is comfortable. According to the WHO, about 85% of cancer patients can be kept comfortable using this protocol.



BOX 72-1

Sequence for Management of Cancer Pain




  • •

    WHO ladder



    • •

      Tier 1—nonopioid analgesics


    • •

      Tier 2—“weak opioids” (in combination with acetaminophen or NSAIDs)


    • •

      Tier 3—pure opioids



  • •

    Tunneled epidural catheters


  • •

    Implantable analgesic devices


  • •

    Neuroablative procedures




In the WHO ladder, first-tier medications include nonopioid analgesics such as nonsteroidal antiinflammatory drugs (NSAIDs), antidepressants, and anticonvulsants. Second-tier medications include “weak opioids,” which have ceiling dosages owing to their combination with acetaminophen or NSAIDs. Third-tier analgesics include all sole opioid preparations, both short-acting and extended-release preparations. Despite the addition of large doses of opioids in the third tier, the nonopioid medications from tier 1 should be continued, taking advantage of their different mechanism of action in treating pain. A good knowledge of opioid equipotency conversions is necessary to be able to change from one opioid to another.


The WHO ladder can be further extrapolated clinically to include invasive techniques. Oral analgesics are tried first, followed by intravenous opioids, analgesia via tunneled epidural catheters, implantable analgesic devices (e.g., intrathecal infusion pumps), and finally neuroablative procedures.




5


What guidelines can be followed in devising a long-term analgesic regimen for treating cancer pain?


Guidelines frequently followed when treating cancer pain use a combination of different classes of analgesics to minimize the side effects of any one medication. The combination should use drugs that work on pain pathways at different levels to take advantage of their additive and synergistic effects, as follows:


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Jul 14, 2019 | Posted by in ANESTHESIA | Comments Off on Cancer pain management

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