What is the best approach for managing cancer pain?

Cancer Pain Management

The best approach for managing cancer pain is to use the WHO analgesic ladder with stepwise escalation based on pain severity: non-opioids for mild pain, weak opioids or low-dose strong opioids for moderate pain, and strong opioids (morphine preferred) for severe pain, combined with around-the-clock dosing, breakthrough medication, and adjuvant analgesics when indicated. 1, 2, 3

Assessment at Every Clinical Encounter

Evaluate all cancer patients for pain at every visit using standardized self-reporting tools such as visual analog scales (VAS), numerical rating scales (NRS), or verbal rating scales (VRS). 1, 2, 3

• Characterize pain by type (nociceptive: somatic or visceral; neuropathic), location, intensity, duration, temporal patterns, and relieving/exacerbating factors. 1, 2
• Assess the impact on function and quality of life, as pain undermines quality of life considerably and is a clinically important indicator of tumor progression. 1
• Begin pain management during the diagnostic evaluation—do not wait for complete workup. 1

Pharmacologic Management by Pain Severity

Mild Pain (WHO Level I)

Start with non-opioid analgesics: acetaminophen/paracetamol (maximum 4000 mg/day) or NSAIDs. 1, 2, 3

• Provide gastroprotection when using NSAIDs long-term to prevent GI toxicity. 2, 3
• Use NSAIDs with caution in patients with renal impairment, heart failure, or hypertension. 2
• Selective COX-2 inhibitors may be considered for patients with gastric intolerance, though toxicity issues remain unsettled and efficacy data for cancer pain are lacking. 1

Moderate Pain (WHO Level II)

Add weak opioids (codeine, dihydrocodeine, tramadol) to non-opioid analgesics for moderate pain persisting despite adequate doses of non-opioids. 1, 3

• Low doses of morphine or equivalents are a reasonable alternative, especially if progressive pain is expected. 1, 3
• Weak opioids may be combined with ongoing use of a non-opioid analgesic but never with WHO level III analgesics. 1

Severe Pain (WHO Level III)

Morphine is the preferred strong opioid for severe pain. 1, 3

• Oral administration is the preferred route; if given parenterally, the equivalent dose is 1/3 of the oral medication. 1
• Hydromorphone or oxycodone (both normal release and modified release formulations) are effective alternatives to oral morphine. 1, 3
• Methadone is an alternative but may be more complicated to use because of pronounced inter-individual differences in plasma half-life and duration of action. 1
• Transdermal fentanyl is best reserved for patients whose opioid requirements are stable at a level corresponding to ≥60 mg/day of morphine. 1
• Strong opioids may be combined with ongoing use of a WHO level I agent. 1

Opioid Dosing Principles

Provide around-the-clock dosing for persistent pain rather than "as needed" administration. 1, 2, 3

• Include "breakthrough doses" (typically 10-15% of total daily dose) for transient pain exacerbations. 1, 2, 3
• Titrate opioid doses to effect as rapidly as possible. 1, 2
• If more than four breakthrough doses are necessary daily, increase the baseline opioid treatment with slow-release formulation. 1, 3

Common Pitfall to Avoid

Do not underdose opioids out of fear of addiction in cancer patients with legitimate pain—this is the most common cause of inadequate pain control. 1 Relief of pain is medically important and there is no medical benefit to suffering with pain. 1

Adjuvant Analgesics for Specific Pain Types

Neuropathic Pain

Add anticonvulsants or antidepressants as coanalgesics in combination with opioids for neuropathic pain. 1, 2, 3

• Gabapentin: Starting dose 100-300 mg nightly, increase to 900-3600 mg daily in divided doses 2-3 times daily. Dose increments of 50-100% every few days. Slower titration for elderly or medically frail. Dose adjustment required for renal insufficiency. 1
• Pregabalin: Starting dose 50 mg 3 times daily; increase to 100 mg 3 times daily. Pregabalin is more efficiently absorbed through the GI tract than gabapentin; may increase further to maximum 600 mg in divided doses 3 times daily. Dose adjustment required for renal insufficiency. 1
• Antidepressants: Duloxetine starting dose 30-60 mg daily, increase to 60-120 mg daily. Venlafaxine starting dose 50-75 mg daily, increase to 75-225 mg daily. 1

Bone Pain

Use bone-modifying agents (bisphosphonates, denosumab) for bone pain. 2, 3

• Consider radiation therapy for localized bone pain. 2, 3
• Consider surgical stabilization for impending fractures. 2, 3

Topical Agents

Lidocaine patch 5% can be applied daily to painful sites with minimal systemic absorption. 1

• Consider NSAID topical formulations: diclofenac gel 3 times daily or diclofenac patch 180 mg once or twice daily. 1

Interventional Approaches

Consider specialty consultation for interventional pain management when pain is inadequately controlled despite optimal pharmacologic therapy or when opioid side effects are intolerable. 2, 3

• Options include regional infusion of analgesics, nerve blocks, and vertebral augmentation (vertebroplasty/kyphoplasty) for vertebral pain with instability. 2, 3

Managing Opioid Side Effects

Anticipate and proactively manage common side effects: constipation, nausea/vomiting, and central nervous system toxicity. 3

• Provide prophylactic laxatives for all patients on opioids. 3
• Use antiemetics as needed. 3
• Consider dose reduction or opioid rotation if side effects are intolerable. 3

Psychosocial Support and Patient Education

Inform patients and families that emotional reactions to pain are normal and are evaluated and treated as part of pain treatment. 1

• Teach coping skills: for acute pain, use breathing exercises and distraction techniques; for chronic pain, add relaxation techniques, guided imagery, and hypnosis. 1
• Educate that pain management is a team effort involving oncologist, nurse, pain specialist, palliative care clinician, physiatrist, neurologist, psychologist, social worker, psychiatrist, physical therapist, and spiritual counselor. 1
• Emphasize that potent analgesics should be taken only as prescribed and by the person for whom the medication is prescribed; patients should not self-adjust dosage or frequency unless discussed with their healthcare provider. 1

Monitoring and Follow-Up

Obtain regular pain ratings and document them in medical records. 2, 3

• Adjust treatment based on changes in pain intensity, side effects, and disease progression. 2, 3
• Provide patients with written follow-up plans and instructions on medication adherence. 3

Key Clinical Context

Over 80% of cancer patients with advanced metastatic disease suffer pain caused mostly by direct tumor infiltration. 1, 3 Approximately 20% of pain in cancer patients may be attributed to effects of surgery, radiotherapy, or chemotherapy. 1, 3 Most cancer patients can attain satisfactory relief through an approach that incorporates primary anti-tumor treatments, systemic analgesic therapy, and non-invasive techniques such as psychological or rehabilitative interventions. 1