What is the role of cannabis tablets in cancer pain management?

Cannabis Tablets in Cancer Pain Management

Cannabis tablets may be considered as an adjuvant analgesic for cancer pain management after conventional treatments have failed, but should not be used as first-line therapy due to limited evidence of efficacy and potential risks. 1, 2

Current Evidence and Recommendations

• The American Society of Clinical Oncology (ASCO) guidelines state that clinicians may follow specific state regulations that allow access to medical cannabis for patients with chronic pain after considering potential benefits and risks of available formulations 1
• However, there is insufficient evidence to recommend medical cannabis for first-line management of chronic pain in cancer survivors 1
• The NCCN guidelines note that data supporting cannabinoids as adjuvant analgesics for cancer pain are extremely limited with somewhat conflicting results 1
• A 2023 Cochrane review found moderate-certainty evidence that oromucosal cannabis preparations (nabiximols) are ineffective in relieving moderate-to-severe opioid-refractory cancer pain 3

Treatment Algorithm for Cancer Pain Management

1. First-line options:

   • Non-opioid analgesics (acetaminophen, NSAIDs)
   • Adjuvant analgesics (anticonvulsants like gabapentin/pregabalin for neuropathic pain)
   • Topical analgesics
   • Weak opioids for moderate pain

2. Second-line options:

   • Strong opioids (morphine, oxycodone, etc.) for severe pain

3. Consider cannabis tablets only when:

   • Conventional treatments have failed to provide adequate relief
   • Patient has persistent moderate-to-severe pain despite optimized conventional therapy
   • Benefits may outweigh risks for the individual patient
   • Legal in your jurisdiction

Formulations and Evidence

• No particular preparation of cannabis has proven superior to others 1
• FDA has not approved any drug product containing or derived from botanical marijuana 1
• Limited evidence suggests that combination THC/CBD products may be more effective than THC alone:
  • Two randomized controlled trials showed that nabiximols (THC/CBD combination) significantly reduced cancer-related pain compared to placebo in patients with inadequate analgesia despite chronic opioid administration 1
  • THC extract alone did not show significant benefit compared to placebo 1

Potential Benefits

• May provide modest analgesia as an adjuvant therapy 1, 2
• May help with multiple symptoms beyond pain:
  • Sleep problems (small improvement with weighted mean difference on 10-cm VAS: -0.19) 2
  • Nausea/vomiting 4
  • Poor appetite 4
  • Anxiety 4

Risks and Side Effects

• Common adverse effects include:

  • Somnolence, fatigue, dizziness, confusion 1
  • Dry mouth, hypotension 1
  • Short-term cognitive impairment 2

• Serious concerns include:

  • Increased risk for motor vehicle accidents 2
  • Psychotic symptoms (contraindicated in patients with history of psychosis) 2
  • Potential for cannabis use disorder 2
  • Route-dependent risks (edible products associated with higher rates of emergency department visits) 1

Clinical Considerations

• Nearly 20% of cancer patients seeking specialized symptom management test positive for THC, suggesting significant unsanctioned self-treatment 5
• Cannabis users tend to be younger, more likely male, and have more recently diagnosed cancer 5
• Patients using cannabis often report more severe symptoms than non-users, which may indicate self-selection by those with more difficult-to-manage symptoms 5, 4
• Assess for current cannabinoid use and provide education on state and federal regulations 1
• Document the discussion of potential benefits and risks with patients

Monitoring

• Regular assessment of pain relief, functional improvement, and side effects
• Screen for cannabis use disorder
• Monitor for drug interactions, particularly with medications metabolized by CYP450 enzymes
• Reassess the need for continued cannabis use at regular intervals