Topical Traditional Chinese Medicines for Cancer Pain: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Abstract

Background and objectives: Safe and effective management of cancer-related pain is a worldwide challenge. In the search for treatment options, natural products used in Chinese herbal medicines (CHMs) have received attention in clinical studies for their effects on cancer-related pain. The objective of this systematic review is to evaluate the clinical evidence for topically applied CHMs as adjunctive treatments for cancer pain management.

Methods: Nine biomedical databases and 4 clinical trial registries were searched for randomized-controlled trials (RCTs) that reported measures of pain and/or quality of life. Risk of bias was assessed using the Cochrane tool. Meta-analysis employed mean difference (MD) with 95% confidence intervals (random effects).

Results: Twenty (20) RCTs (1636 participants) met the inclusion criteria. Meta-analyses were grouped based on the comparisons and outcome measures. For pain intensity, there was a greater reduction in the topical CHM group versus placebo (MD -0.72 [-1.04, -0.40]), no difference when compared to tramadol (MD -0.15 [-0.38, 0.08]), and a greater reduction when topical CHMs were combined with conventional analgesic medications (MD -0.67 [-0.93, -0.40]). Analgesic onset time was reduced in the CHM group compared to tramadol (MD -26.02 [-27.57, -24.47] minutes), and for CHMs combined with conventional medications (MD -19.17 [-21.83, -16.52] minutes). When CHMs were combined with analgesic medications, improvements were found for duration of analgesia (MD 1.65 [0.78, 2.51] hours), analgesic maintenance dose (MD -31.72 [-50.43, -13.01] milligrams/day), and quality of life.

Conclusion: Addition of topical CHMs to conventional analgesic medications was associated with improved outcomes for pain intensity, some other pain-related outcomes, and measures of quality of life. Limitations included methodological issues in some studies and considerable heterogeneity in some pooled results.

Keywords: Chinese medicine; cancer pain; herbal medicine; meta-analysis; natural products; topical analgesic; traditional medicine.

Figure 1.

PRISMA flow diagram of study selection.

Figure 2.

Forest Plots. (a) Cancer Pain Intensity. (b) Analgesic Onset Time (minutes). (c) Analgesia Duration (hours). (d) Analgesic dose. (e) Quality of Life. (f) Karnofsky Performance Status.