Traditional chinese medicine for cancer pain: a scoping review protocol of systematic reviews and meta-analyses

Pain is one of the most common and distressing symptoms among cancer patients. In 2022, approximately 20 million new cancer cases were diagnosed worldwide[1]. The overall incidence of cancer-related pain averages 50.7%, rising to 66.4% in patients with advanced cancer, of whom one-third experience severe pain[2]. Pain significantly impairs patients' quality of life and imposes a considerable economic burden. Studies have shown that the total medical costs for patients with cancer pain are 50% to 75% higher than those without pain[3,4]. Cancer pain management is recognized by the World Health Organization (WHO) as a central component of oncology palliative care[5]. The WHO analgesic ladder, which emphasizes opioid medications, remains a cornerstone of treatment. However, pharmacological interventions are often associated with adverse effects such as constipation and nausea, along with risks of tolerance and addiction[6]. Long-term opioid use may also lead to serious complications, including cognitive impairment and immunosuppression[7]. Traditional Chinese Medicine (TCM), as a holistic medical system, is widely used as a complementary therapy for cancer pain. TCM theory attributes cancer pain primarily to “qi stagnation and blood stasis” and “phlegm-dampness obstruction”. Treatment strategies focus on reinforcing healthy qi, eliminating pathogenic factors, and unblocking meridians to alleviate pain[8]. Various TCM modalities—including herbal decoctions, proprietary Chinese medicines, herbal injections, and topical applications—have demonstrated promising analgesic effects in clinical practice. For example, Cinobufacini preparations have shown overall response rates of 50.0% to 86.7% in moderate to severe cancer pain, particularly in cases related to gastrointestinal tumors, lung cancer, and bone metastases[9]. Similarly, Corydalis yanhusuo extract has achieved pain relief rates of 60.0% to 85.0% in cancer pain, while reducing opioid dosage and adverse reactions[10]. In recent years, a growing number of systematic reviews (SRs) and meta-analyses (MAs) have evaluated the efficacy and safety of TCM for cancer pain. Nevertheless, current research on TCM for cancer pain remains fragmented. Existing SRs and MAs often focus on single herbs or specific cancer types, and their methodological quality has not been comprehensively assessed. Therefore, this scoping review aims to: (1) summarize current evidence on the efficacy and safety of TCM for cancer pain; (2) evaluate the methodological quality of included SRs and MAs, and (3) provide a foundation for future meta-analyses and identify directions for future research.