Cancer Pain Management

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Cancer Pain Fundamentals - The Painful Truth

  • Prevalence: Affects 50-80% of cancer patients, severely impacting Quality of Life (QoL).
  • Etiology: Tumor invasion/compression, treatment side-effects (chemo, radio, surgery), paraneoplastic syndromes.
  • Types: Nociceptive (somatic, visceral), neuropathic; often mixed.
  • Assessment: Crucial. Use PQRST mnemonic (📌). Scales: Numeric Rating Scale (NRS 0-10), Visual Analog Scale (VAS), Brief Pain Inventory (BPI).

    ⭐ The WHO three-step analgesic ladder is a cornerstone of cancer pain management, guiding stepwise opioid and adjuvant use. oka

WHO Ladder & Basics - Stepping Up Relief

WHO 3-step ladder: Key principles are "By the mouth", "By the clock", "By the ladder", and individualized therapy.

  • Step 1 (Mild Pain): Non-opioid (e.g., Paracetamol, NSAID) ± Adjuvant.
  • Step 2 (Moderate Pain): Weak opioid (e.g., Tramadol, Codeine) ± Non-opioid ± Adjuvant.
  • Step 3 (Severe Pain): Strong opioid (e.g., Morphine, Fentanyl) ± Non-opioid ± Adjuvant.
    • Adjuvants (e.g., Gabapentinoids, TCAs) for specific pain types.

WHO Analgesic Ladder for Cancer Pain Management

⭐ Prophylactic laxatives (e.g., senna + docusate) should be prescribed with opioids to prevent constipation.

Opioid Arsenal - Potent Painkillers

  • Morphine: Gold standard (PO, IV, SC).
    • M6G (active metabolite, renal excretion).
    • SE: Nausea, constipation, sedation, resp. depression.
  • Fentanyl: Potent (80-100x morphine).
    • Patch (stable chronic pain), transmucosal (BTcP).
    • Safer in renal failure.
  • Methadone: Long, variable T½. Mu-agonist, NMDA antagonist (neuropathic pain).
    • ⚠️ QT prolongation risk; careful titration.
  • Tapentadol: Mu-agonist & NRI (Norepinephrine Reuptake Inhibitor).
    • ↓ constipation compared to other opioids.
  • Buprenorphine: Partial mu-agonist.
    • Ceiling effect on respiratory depression.
    • Sublingual, transdermal routes.
  • Tramadol: Weak mu-agonist, SNRI.
    • Max dose 400mg/day.
    • Seizure risk; serotonin syndrome risk.

⭐ M6G (morphine's active metabolite) accumulates in renal failure; consider dose ↓ or switch opioid (e.g., to fentanyl or methadone).

Adjuvants & Co-analgesics - Helper Meds

  • Purpose: Enhance opioid efficacy, manage specific pain types (neuropathic, bone), reduce opioid side effects.
  • Neuropathic Pain:
    • Antidepressants: Amitriptyline (10-25 mg HS), Duloxetine (30-60 mg OD).
    • Anticonvulsants: Gabapentin (start 100-300 mg), Pregabalin (start 25-75 mg).
  • Bone Pain:
    • NSAIDs (use cautiously).
    • Corticosteroids: Dexamethasone (4-8 mg BD) for inflammation, nerve compression.
    • Bisphosphonates (e.g., Zoledronic acid), Denosumab.
  • Other Key Adjuvants:
    • Ketamine (low dose): Refractory neuropathic pain, opioid-induced hyperalgesia.

⭐ For neuropathic cancer pain, gabapentinoids (Gabapentin, Pregabalin) and TCAs (Amitriptyline) are often first-line adjuvants.

Interventional Strategies - Beyond Pills

  • Neurolytic Blocks: Chemical (alcohol) or thermal ablation.
    • Celiac plexus (pancreatic, upper GI cancer).
    • Superior hypogastric plexus (pelvic pain).
    • Ganglion Impar (perineal, coccygeal pain).
  • Intrathecal Drug Delivery (IDDS): Refractory pain; opioids, ziconotide.
  • Spinal Cord Stimulation (SCS): Neuropathic pain.
  • Vertebroplasty/Kyphoplasty: Painful vertebral fractures.
  • Cordotomy: For intractable unilateral somatic pain.

⭐ Celiac plexus neurolysis offers significant pain relief for 60-90% of patients with pancreatic cancer pain.

High‑Yield Points - ⚡ Biggest Takeaways

  • The WHO analgesic ladder (non-opioid → weak opioid → strong opioid) is fundamental for cancer pain management.
  • Opioids (e.g., morphine, fentanyl) are central; titrate to effect and proactively manage side effects like constipation.
  • Adjuvant analgesics (gabapentinoids, TCAs, corticosteroids) are crucial for neuropathic or bone pain.
  • Non-opioid analgesics (NSAIDs, paracetamol) are used for mild pain or as adjuncts; monitor NSAID toxicity.
  • Interventional techniques (nerve blocks, neurolysis, spinal opioids) are considered for severe, refractory pain.
  • Address breakthrough pain with short-acting opioids; regular pain assessment and reassessment are vital for effective therapy.
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Practice Questions: Cancer Pain Management

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Isotopes used in the relief of metastatic bone pain include – a) Strontium–89 b) I–131 c) Gold–198 d) P–32 e) Rhenium–186

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Flashcards: Cancer Pain Management

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What kind of pain (musculoskeletal/neurogenic) can be managed using transcutaneous electrical nerve stimulation (TENS)?_____

TAP TO REVEAL ANSWER

What kind of pain (musculoskeletal/neurogenic) can be managed using transcutaneous electrical nerve stimulation (TENS)?_____

Both

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