Cancer Pain

Overview

• ~1.75 million people are diagnosed with cancer every year
• Up to 90% of patients with advanced cancer have pain that significantly impacts function, mood, sleep
• In 1984, WHO stepladder was introduced for management of cancer pain

• Pain management typically relies on the WHO stepladder, but analgesia may be inadequate for 10-25% of cancer patients
• Interventional options such as nerve blocks and intrathecal therapy may be appropriate
  • Celiac plexus block/neurolysis for abdominal pain
  • Superior hypogastric plexus block/neurolysis for pelvic pain
  • Intrathecal therapy for regional cancer-related nociceptive or neuropathic pain

Clinical Use

Clinical Challenges

• Cancer-related pain is very broad
• Can be directly caused by the tumor itself or be an effect of treatment
  • E.g. chemotherapy-induced peripheral neuropathy, arthritis from immunotherapy, radiation neuropathies
• May be either nociceptive or neuropathic
  • Nociceptive pain: bony metastases, soft tissue involvement, pathological fractures, visceral involvement
  • Neuropathic pain: tumor invasion, nerve injury after surgery (post-thoracotomy pain, post-mastectomy pain), radiation neuritis, tumor invasion into nerves
• Cancer pain is a moving target: disease may spread to many locations, cause different patterns of pain, or have mixed etiologies
• Side effects of treatment may overlap with underlying disease and treatment effects
  • For example, fatigue could be due to opioids, but also due to or compounded by chemotherapy treatment, disease progression or the experience of chronic pain itself.
  • Altered mental status may be due to opioids, but could also be due to or compounded by organ failure, metabolic derangements or metastatic brain disease. 

Clinical Recomendations

• Start with oral/parenteral medications for cancer pain 
• Don’t forget about adjuvant medications like neuropathic medications for cancer-related pain
• Progressive disease may require quick uptitration of opioid medications.
• Interventional options, such as nerve blocks and intrathecal pumps, are appropriate for patients with poorly controlled pain or intolerable side effects.

Special Considerations

• Patients’ cancer-targeted therapies may increase risk associated with interventional procedure:
  • Chemotherapeutics may cause myelosuppression leading to neutropenia, thrombocytopenia, or coagulopathies
  • Certain immunotherapeutics, such as bevacizumab, a VEGF inhibitor, can cause severe bleeding and poor wound healing
    • May want to avoid placing perioperative epidurals for these patients as well!
    • Bevacizimab must be held for 28 days before and after elective surgery.
• May have physiological alterations to gut, liver, kidneys as a result of cancer/surgical intervention that may affect absorption, pharmacokinetics of many medications