What are the recommended approaches for pain relief in cancer patients?

Pain Relief for Cancer Patients

Cancer pain should be managed using the WHO analgesic ladder, starting with non-opioids for mild pain, progressing to weak opioids or low-dose strong opioids for moderate pain, and using strong opioids (morphine preferred) for severe pain, with around-the-clock dosing rather than as-needed administration. 1, 2

Pain Assessment at Every Visit

• Evaluate all cancer patients for pain at every clinical encounter using standardized self-reporting tools such as numerical rating scales (NRS), visual analog scales (VAS), or verbal rating scales 1, 2
• Score pain intensity as mild (NRS ≤4), moderate (NRS 5-6), or severe (NRS ≥7) to guide treatment selection 1
• For cognitively impaired patients, observe pain-related behaviors including facial expressions, body movements, and vocalizations 2
• Begin pain management during the diagnostic evaluation rather than waiting for definitive diagnosis 1

Mild Pain (NRS ≤4): WHO Step 1

• Use paracetamol/acetaminophen (maximum 4000 mg/day) or NSAIDs as first-line therapy 1, 2
• However, recent high-quality evidence shows paracetamol provides no additional benefit when added to strong opioids, so avoid using it in patients already on Step 3 medications 3, 4
• NSAIDs are superior to placebo in single-dose studies, though no specific NSAID demonstrates superior efficacy or safety over others 1
• Consider selective COX-2 inhibitors for patients with gastric intolerance, though solid efficacy data for cancer pain are lacking 1

Moderate Pain (NRS 5-6): WHO Step 2

• Add weak opioids (codeine, dihydrocodeine, tramadol) to non-opioid analgesics 1
• Alternatively, use low doses of strong opioids (morphine or equivalents) instead of weak opioids, especially when progressive pain is anticipated 1, 2
• The second step has significant limitations: no definitive proof of efficacy over non-opioids alone, ceiling effect preventing dose escalation, and effectiveness typically limited to 30-40 days 1
• Many experts advocate skipping Step 2 entirely and moving directly to low-dose morphine for moderate pain 1

Severe Pain (NRS ≥7): WHO Step 3

• Morphine is the preferred strong opioid for severe cancer pain 1, 2
• Oral administration is the preferred route; if parenteral administration is necessary, use one-third of the oral dose 1
• Alternative strong opioids include hydromorphone, oxycodone (both available in immediate-release and modified-release formulations), methadone (complicated by inter-individual variability in half-life), and transdermal fentanyl 1, 2
• Reserve transdermal fentanyl for patients with stable opioid requirements corresponding to ≥60 mg/day of oral morphine 1

Critical Dosing Principles

• Provide around-the-clock scheduled dosing for persistent pain, not "as needed" administration 1, 2
• Prescribe breakthrough doses equivalent to 10-15% of the total daily dose for transient pain exacerbations 1, 2
• If more than four breakthrough doses are required daily, increase the baseline long-acting opioid regimen 1, 2
• Titrate opioid doses rapidly to effect to prevent unnecessary suffering 1, 2

Managing Opioid Side Effects

• Anticipate and proactively manage constipation with prophylactic stimulant laxatives (with or without stool softeners) in all patients starting opioids 1, 2
• Treat nausea with antiemetics, drowsiness with psychostimulants, and confusion with major tranquilizers 1
• Consider opioid rotation (switching to another opioid agonist) or route change if side effects are intolerable despite dose adjustments 1, 2
• Reduce opioid dose by adding co-analgesics or using alternative approaches such as nerve blocks or radiotherapy 1

Adjuvant Analgesics for Specific Pain Types

• Use anticonvulsants (gabapentin, pregabalin) or antidepressants (tricyclics, SNRIs) for neuropathic pain characterized by shooting, sharp, stabbing, or tingling sensations 2
• Add corticosteroids to reduce inflammation and nerve compression 2
• Prescribe bisphosphonates or denosumab for bone pain from metastases 2, 4
• Note that evidence for anticonvulsants, antidepressants, and corticosteroids in cancer pain requires further research despite guideline recommendations 4

Non-Pharmacological and Interventional Approaches

• Use radiation therapy for localized bone pain from metastases 2, 4
• Consider surgical stabilization for impending pathological fractures 2
• Employ interventional strategies (regional analgesic infusions, nerve blocks, vertebral augmentation) when pain remains inadequately controlled despite optimal pharmacotherapy or when opioid side effects are intolerable 2
• Incorporate psychological interventions to address anxiety and depression that amplify pain perception 1, 2

Common Pitfalls to Avoid

• Do not combine weak opioids (Step 2) with strong opioids (Step 3) 1
• Avoid using paracetamol in patients already taking strong opioids, as it provides no additional analgesic benefit 3, 4
• Do not wait for scheduled dosing intervals when rapid titration is needed for severe pain 1
• Never undertreat acute cancer pain, as this decreases subsequent responsiveness to opioid analgesics 5

Monitoring Requirements

• Document pain ratings at every visit using standardized scales 2
• Adjust treatment based on changes in pain intensity, side effects, and disease progression 2
• Provide written follow-up plans and medication adherence instructions 2

Context and Prevalence

• Over 80% of patients with advanced metastatic cancer experience pain, primarily from direct tumor infiltration 1, 2
• Approximately 20% of cancer pain results from treatment effects (surgery, radiotherapy, chemotherapy) rather than the cancer itself 1
• Despite decades of guideline implementation, cancer pain remains undertreated in at least one-third of patients with moderate to severe pain 5, 4