Ketamine for cancer pain: what is the evidence?

Area of Science:

• Oncology
• Pain Management
• Pharmacology

Background:

• Ketamine, an N-methyl-D-aspartate receptor antagonist, offers analgesic properties at low doses.
• It is often used as an adjuvant therapy for opioid-resistant cancer pain or neuropathic pain.
• Clinical practice shows varied responses to ketamine in managing difficult cancer pain scenarios.

Purpose of the Study:

• To review the efficacy of ketamine in treating terminal cancer pain refractory to opioids or complicated by neuropathy.
• To reconcile conflicting findings between randomized controlled trials and observational studies regarding ketamine's benefit.

Main Methods:

• A literature search was conducted to identify randomized controlled trials (RCTs) on ketamine for opioid-refractory cancer pain.
• Observational studies, including open-label studies and case series, were also considered.
• Methodological differences between study types were analyzed to explain outcome discrepancies.

Main Results:

• Four RCTs found no clinically significant benefit of ketamine in reducing pain or opioid consumption.
• Conversely, numerous open-label studies and case series reported positive outcomes with ketamine treatment.
• This discrepancy suggests potential methodological limitations influencing study results.

Conclusions:

• Current evidence from RCTs indicates a lack of benefit for ketamine as an adjuvant analgesic in cancer pain.
• However, the consistent positive findings in observational data warrant further investigation.
• There is insufficient evidence to definitively conclude that ketamine is ineffective for cancer pain management.