Red flags
- New back pain + limb weakness/sensory level/sphincter disturbance - malignant spinal cord compression - MRI whole spine + dexamethasone within hours, not days
- Sudden severe pain at a known metastasis site after minor trauma/movement - pathological fracture
- Severe unremitting abdominal pain with distension - bowel obstruction
- New headache + neurological signs - raised ICP / brain metastases
- Pain out of proportion, unresponsive to escalating opioid + agitation - consider undiagnosed cause (obstruction, retention, fracture), not simply "worsening cancer pain"
- Rapidly escalating opioid requirement - reassess mechanism/diagnosis before just increasing dose
Differential by mechanism
By mechanism
- Nociceptive - somatic - bone metastases, soft tissue infiltration, post-surgical - well localised, aching/throbbing
- Nociceptive - visceral - organ capsule stretch, obstruction - poorly localised, cramping/colicky, referred
- Neuropathic - nerve/plexus infiltration, chemotherapy-induced peripheral neuropathy, post-herpetic - burning, shooting, allodynia
- Mixed - very common in advanced cancer (e.g. vertebral metastasis with cord/root involvement)
By cause (in the palliative population, not all pain is cancer pain)
- Disease-related - tumour mass effect, bone metastases, nerve infiltration, organ obstruction
- Treatment-related - post-surgical, radiotherapy fibrosis/plexopathy, chemotherapy neuropathy, mucositis
- Debility-related - pressure injury, constipation, urinary retention, muscle spasm/contracture
- Unrelated comorbid pain - osteoarthritis, pre-existing back pain - do not attribute all pain to the malignancy
Focused history
Characterise systematically
- Site(s) - pain is frequently multifocal in advanced cancer, characterise each site separately
- Character, radiation, timing (constant vs incident/breakthrough), severity (0-10)
- Aggravating/relieving factors - incident pain (movement-related) needs a different strategy to background pain
- Current analgesia, response, side effects, adherence
Screen for the total pain concept
- Psychological distress, spiritual/existential distress, social/family concerns, financial stress - all modulate the pain experience and response to analgesia
- Sleep disturbance, mood, prior substance use history (informs opioid stewardship, not a reason to withhold)
Focused examination
- Examine each reported pain site directly - deformity, tenderness, swelling, neurological deficit
- Full neurological exam if any back/neck pain - power, sensation, reflexes, sphincter tone, saddle sensation
- Abdominal exam - distension, bowel sounds, palpable bladder/mass
- Assess function - mobility, ability to perform ADLs, impact on sleep
Investigation strategy
- Often clinical - do not over-investigate if goals of care are comfort-focused and findings would not change management
- Imaging when it changes management: MRI spine for suspected cord compression (urgent), plain film/CT for suspected pathological fracture, bone scan/CT for staging new pain sites
- Bloods - calcium (hypercalcaemia can present as pain + confusion), renal function (guides opioid choice/dose)
- Reassess response to analgesia as an ongoing "investigation" - a validated pain score at each review
Management
Principle - match the drug to the mechanism, not a rigid ladder step
- The WHO analgesic ladder remains a useful concept but is not a mandatory stepwise sequence - move directly to strong opioids for severe pain rather than trialling weak opioids first
By mechanism
| Pain type | First-line |
|---|---|
| Nociceptive | Paracetamol, NSAID (if not contraindicated), opioid titrated to effect |
| Neuropathic | Adjuvant - amitriptyline or gabapentin/pregabalin; opioids less reliably effective alone |
| Bone metastases | NSAID, radiotherapy (single-fraction as effective as multi-fraction for uncomplicated bone pain), bisphosphonate/denosumab, opioid |
| Bowel colic | Avoid stimulant laxatives/prokinetics if obstructive; hyoscine butylbromide for spasm |
Opioid titration
- Start with an immediate-release opioid, titrate to effect, then convert total 24h dose to a modified-release background + immediate-release breakthrough (1/6-1/10 of the 24h dose)
- Always co-prescribe a laxative with any regular opioid - constipation is near-universal, not a side effect to wait out
- Anticipate and manage nausea (common in first days, usually settles)
- Opioid switching/rotation for inadequate analgesia or intolerable side effects - use published equianalgesic tables and reduce the calculated dose by 25-50% for incomplete cross-tolerance
- Renal impairment - avoid morphine accumulation (active metabolites); fentanyl or buprenorphine safer
Incident/breakthrough pain
- Fast-onset formulation (e.g. sublingual/transmucosal fentanyl) timed before a predictable trigger (dressing change, transfer)
Non-pharmacological
- Radiotherapy, nerve blocks/interventional procedures, physiotherapy, TENS, psychological support - address the total pain, not analgesia alone
Traps
- Assuming all new pain is progressive cancer - always consider a treatable unrelated cause (retention, constipation, fracture, unrelated arthritis)
- Rigidly following the WHO ladder in severe pain, delaying an effective strong opioid
- Starting an opioid without a laxative
- Treating neuropathic pain with opioid dose escalation alone rather than adding an appropriate adjuvant
- Missing spinal cord compression because back pain is attributed reflexively to "bone mets, as usual"
- Fear of opioid use ("opiophobia") in staff or family leading to undertreatment at end of life - appropriate titration to comfort is not hastening death
Talk track
1. Characterise before treating
- "I map every pain site separately and ask what kind of pain it is - nociceptive, neuropathic, or mixed - because that dictates the drug."
2. Exclude the emergency
- "New back pain always gets a neuro exam - I'm not missing cord compression."
3. Match drug to mechanism, don't just climb a ladder
- "Severe pain gets a strong opioid directly; neuropathic pain gets an adjuvant, not just more opioid."
4. Titrate, convert, and always cover the side effects
- "Immediate-release to find the dose, then a background plus breakthrough regimen, with a laxative from day one."
5. Remember total pain
- "Psychological and existential distress amplify physical pain - I address both."
8 of 8 sections written · drafted 2026-09-13