Managing Cancer Pain

Documents to Request

• Current medication list with all analgesics, doses, and schedules
• Pain assessment history (serial pain scores with dates)
• PDMP report (state prescription monitoring database)
• Relevant imaging (to identify pain source — bone metastases, nerve compression, visceral involvement)
• Renal function (CrCl) and hepatic function (LFTs, albumin, INR) labs
• Prior interventional pain procedures if applicable
• Palliative radiation therapy history if applicable
• Substance use disorder screening results

Step 1: Conduct Comprehensive Pain Assessment

OPQRSTUV mnemonic for cancer pain assessment:

Pain classification:

• Nociceptive (somatic): Well-localized, aching, throbbing — bone metastases, post-surgical
• Visceral: Poorly localized, deep, crampy — organ involvement, peritoneal disease
• Neuropathic: Burning, shooting, electric — nerve compression, plexopathy, chemotherapy-induced
• Mixed: Most cancer pain is mixed — identify each component for targeted treatment

Step 2: Apply the WHO Analgesic Ladder with Modifications

WHO Three-Step Ladder (modified for current oncology practice):

Adjuvant analgesics by pain type:

• Neuropathic pain: Gabapentin (300–3600mg/day), pregabalin (75–300mg BID), duloxetine (60mg/day), TCAs (nortriptyline, desipramine)
• Bone pain: NSAIDs, corticosteroids (dexamethasone 4–8mg), bisphosphonates (zoledronic acid), denosumab, palliative radiation
• Visceral pain: Corticosteroids for obstruction/capsular stretch, octreotide for bowel obstruction
• Muscle spasm: Baclofen, cyclobenzaprine, benzodiazepines (short-term)

Step 3: Opioid Initiation and Titration

For opioid-naive patients:

• Start with short-acting opioid: morphine 5–15mg PO q4h, or oxycodone 5–10mg PO q4h
• Avoid methadone and fentanyl patches in opioid-naive patients
• Assess response at 24–48 hours; titrate by 25–50% for inadequate relief

Conversion to long-acting (when stable dose established):

1. Calculate total 24-hour opioid consumption
2. Convert to morphine equivalent daily dose (MEDD) using equianalgesic table:

3. Reduce by 25–50% for incomplete cross-tolerance when switching opioids
4. Prescribe breakthrough dose: 10–20% of total 24-hour MEDD as immediate-release q1-2h PRN

Breakthrough pain management:

• Breakthrough dose = 10–20% of total 24-hour opioid dose
• If ≥4 breakthrough doses used per day, increase the around-the-clock dose by adding total breakthrough opioid used to the daily regimen
• Transmucosal fentanyl (TIRF products) for rapid-onset breakthrough: restricted to opioid-tolerant patients via TIRF REMS

Step 4: Manage Opioid Side Effects and Monitor Safety

Mandatory prophylaxis: Start a bowel regimen with every opioid prescription — senna + docusate or PEG daily. Opioid-induced constipation does not develop tolerance.

Common side effects and management:

Safety monitoring:

• PDMP check at initiation and periodically during treatment
• Urine drug testing: consider at baseline and periodically, applied with sensitivity in cancer patients
• Assess for opioid-induced hyperalgesia (increasing pain despite increasing doses without disease progression)
• Document risk-benefit assessment for opioid continuation at each visit

Checkpoint B: Post-Draft Alignment (Mandatory)

1. Is pain assessed using a standardized tool with documented pain score and functional impact?
2. Is the analgesic plan matched to pain severity (WHO step) and pain type (nociceptive, neuropathic, mixed)?
3. Are equianalgesic calculations documented for opioid conversions and rotations?
4. Is a breakthrough dose prescribed at 10–20% of total daily opioid and available on the regimen?
5. Are opioid side effects proactively managed (bowel regimen prescribed, nausea plan in place)?

Quality Audit

• Comprehensive pain assessment (OPQRSTUV or equivalent) documented
• Pain classified by type (nociceptive, visceral, neuropathic, mixed)
• WHO analgesic ladder step appropriate for pain severity
• Adjuvant analgesics prescribed for neuropathic or bone pain components
• Opioid selection appropriate for patient status (naive vs. tolerant)
• Equianalgesic calculations documented for opioid conversion
• Cross-tolerance reduction (25–50%) applied when rotating opioids
• Breakthrough dose calculated at 10–20% of total daily dose
• Bowel regimen prescribed with every opioid
• PDMP checked and documented
• Substance use disorder risk assessed with validated screening tool
• Pain score reassessment scheduled with specific timeline
• Non-pharmacologic interventions considered (radiation, nerve blocks, physical therapy)
• Naloxone prescribed for patients at risk of respiratory depression

Guidelines

• Cancer pain requires regular, around-the-clock dosing — PRN-only regimens are inadequate for moderate to severe chronic cancer pain
• There is no maximum dose for pure opioid agonists (morphine, oxycodone, hydromorphone, fentanyl) — titrate to effect as tolerated
• Always start a bowel regimen when initiating an opioid — opioid-induced constipation does not resolve with tolerance
• Fentanyl patches are only for opioid-tolerant patients (per FDA: ≥60mg oral morphine equivalent per day for ≥1 week)
• Avoid meperidine in cancer patients — neurotoxic metabolite (normeperidine) accumulates with repeated dosing
• Methadone has unique pharmacology (variable half-life, NMDA receptor activity, QTc prolongation risk) — initiate only with specialist guidance or established institutional protocol
• Palliative radiation for painful bone metastases can provide relief in 60–80% of patients — consider for localized pain
• Interventional procedures (nerve blocks, intrathecal pumps, vertebroplasty) should be considered when systemic opioid doses are escalating with inadequate relief or intolerable side effects