Cancer Pain Management & Palliative Care

The WHO analgesic ladder seems straightforward — until a patient with bone metastases rates pain at 8/10 and you must decide whether to hold the opioid because they're sedated. Palliative pain management is where comfort meets clinical judgment.

Cancer pain management follows the WHO three-step analgesic ladder: Step 1 (mild pain 1-3) uses non-opioids like acetaminophen or NSAIDs; Step 2 (moderate pain 4-6) adds weak opioids such as tramadol or codeine; Step 3 (severe pain 7-10) uses strong opioids like morphine, hydromorphone, or fentanyl. The guiding principle is around-the-clock (ATC) dosing for constant pain with breakthrough doses (typically 10-15% of the total 24-hour opioid dose) available as needed. Adjuvant medications are added at any step: corticosteroids and bisphosphonates for bone pain, gabapentin or pregabalin for neuropathic pain, antidepressants for mixed pain syndromes. In palliative care, the goal shifts from cure to comfort. Respiratory depression risk decreases in opioid-tolerant patients because tolerance to respiratory depression develops alongside analgesic tolerance. Sedation precedes respiratory depression — monitor sedation level as the earliest warning sign. Pain is whatever the patient says it is; the nurse advocates for adequate dosing even when the patient appears comfortable between assessments. Equianalgesic dosing is essential when rotating opioids: oral morphine 30 mg ≈ IV morphine 10 mg ≈ oral hydromorphone 4 mg. When switching opioids, reduce the calculated equianalgesic dose by 25-50% to account for incomplete cross-tolerance.

Key Distinctions

Don't confuse physical dependence (expected physiologic adaptation) with addiction (compulsive drug-seeking despite harm) — withholding opioids based on addiction fears undertreats cancer pain. Students mix up tolerance (needing higher doses for the same effect) with disease progression causing increased pain — both require dose increases, but the clinical reasoning differs. Sedation is the earliest sign of respiratory depression, not a decreased respiratory rate — assess sedation scales before counting breaths.

Clinical Pearl

Sedation before respiration: if your opioid patient is increasingly drowsy, the respiratory depression alarm is already ringing. Check sedation level first, respiratory rate second.