CANCER PAIN CANCER PAIN MANAGEMENTMANAGEMENT

Pain control should encompass “total pain”  Pain management specialists should not work in isolation Education is fundamental to good pain management

Cancer pain management

A survey of physicians actively involved in cancer care 1/3 wait until prognosis <6 months before giving maximal analgesia (Von Roenn et al. 1993) A study of 81 doctors only 5% could convert a parenteral dose of morphine to an equivalent of MST they were unfamiliar with palliative use of radiation (Mortimer and Bartlett 1997).  

Education in cancer pain management

Cancer pain has increased worldwidean ageing population

 WHO - 4 million people in the world have cancer painSite of primary tumour important Pain not usually significant in early disease 1/3 with metastatic disease have significant pain Most patients with end stage disease have pain >50% patients report <70% pain relief with analgesics

Breakthrough pain  Transitory exacerbation of severe pain on a background of otherwise stable chronic pain in a patient on regular opioids Incidence about 63% Median number 4 severe breakthroughs per day Median duration 30 minutesIncident pain is breakthrough pain related to movement(Portenoy & Hagen, 1990)

Basic pain management principles Decrease pain and improve quality of life

Do no further harmAllow patient and carers choices

Use resources as effectively as possible

Disease modification

SurgeryRadiationChemotherapyBiological therapy

Basic pain managementOral opioid analgesicsAdjuvant analgesicsWHO principles Neuropathic painIndividual variationOpioid switching

Clinical bottom line Paracetamol remains 1st line Topical NSAIDs do work (NNT = 3) - no GI side effects  NSAID Ibuprofen (<2400 mg/day) probably 1st choice

GI protection for those at risk COXIBs offer advantages in terms of GI safety

short prognosis

Adjuvant analgesics Tricyclic antidepressants NNT = 3.0 30% patients >50% pain relief30% minor adverse reactions 4% have to stop treatment

SSRIs less effective (50% reduction side effects)

No difference in efficacy across different pain conditions  

Adjuvant analgesics – anticonvulsants

NNT = 2.6 in trigeminal neuralgia

Evidence of efficacy in diabetic neuropathy Evidence of efficacy in migraine prophylaxis

Relatively high risk for minor adverse effects

Difficult cancer pain may need specialist pain management The WHO guidelines fail in 10-15% patients This may be due to: -

opioid resistanceintolerable drug side effectsinability to deliver drugs effectively e.g. GI problems

Alternatives  local anaesthetic/steroid somatic/sympathetic nerve blocks neurolytic blocksspinal ITDDneuro-destructive surgical procedures

Combined approach aimed at several different levels within the nervous system provides optimum relief with least adverse effects

Simple nerve blocks

ComplexNerve Blocks

Autonomic NerveBlocks

Spinal drug delivery Much smaller drug doses are needed

2% patients with cancer pain

When simpler and more economic methods have failed Indications failure of systemic treatment

intolerable drug side effects

Epidural or intrathecal drug delivery

External & internal systems

Choice of patient for spinal drugs Contraindications Local or systemic infectionNon-correctable co-aggulopathy Patient refusal  IndicationsSegmental pain or spasticity Not head pain ? Neuropathic pain, ? Visceral pain, incident and cutaneous pain

Investigations

Cord compression ?

Good CSF flow

Life expectancy

External or internal systems

Life expectancy > 3 months ?

Intrathecal or epidural drug delivery?

Intrathecal drugs need not pass dura

Used in lower doses (10-20% epidural dose).

Large volume epidurally - spinal cord compression

Change in epidural fat influences drug delivery.

Epidural catheters blocked by fibrosis

Intrathecal or epidural drug delivery? 

Complications within 20 days after implantIntrathecal 25% Epidural 8% CSF leak was the main intrathecal complication Complications after 20 days after implantIntrathecal 5% Epidural 55% Epidurals frequently obstruct or dislodge

Implantable or external system?

•Pain problem•Patient’s condition•Experience of the team

Spinal drugs – infection  Infection rates vary 1 per 168 - 1 per 2446 catheter days 20% cultures from cassettes, syringes and filterscolonised without clinical  Infection associated with prolonged catheter placement time > 100 min

Medtronic system

Spinal drug delivery Pain may change as patient approaches the end of life

Small pump reservoir may mean alternative method of analgesia needed

Clinical bottom line Pain relief better with intrathecal than epidural systemsTreatment failures more common with external epidural catheters compared with internal IT catheters  Treatment failures less common with internalised IT catheters than with internalised epidural catheters  Higher rates of system removal with internalised epidural catheters than with internalised IT catheters  Higher rates of catheter complications with epidural than with IT catheters

Spinal drugs OpioidsClonidineKetamineOctreotideMidazolamNeostigmineBaclofen Local anaesthetics Ziconatide

Spinal drugs – adverse effects Dose escalation - Spinal opioid rotation  Sedation or itching with opioidsHypotension with clonidine Motor block with local anaesthetics Subtle personality change with ketamine Hormonal and immune suppression with opioids

Conclusions A multi-disciplinary approach

Lessons now being applied to Non-cancer pain

>25,000 patients have been treated world-wide