Acupuncture for cancer pain: a scoping review of systematic reviews and meta-analyses

Cancer-related pain is a reality that affects approximately 70% of oncology patients, representing one of the most complex and challenging symptoms in clinical management. This pain is not limited to physical sensation alone but profoundly interferes with patients' quality of life, affecting activities of daily living, cognitive function, sleep quality, and even emotional and psychological well-being. Although the conventional therapeutic arsenal includes opioids, anti-inflammatories, and anticonvulsants, these are often accompanied by significant side effects, including tolerance, physical dependence, constipation, nausea, vomiting, and respiratory depression. In this context, acupuncture has emerged as a promising therapeutic alternative and is in fact recommended by the American Society of Clinical Oncology and the National Comprehensive Cancer Network as part of nonpharmacological interventions for the management of cancer-related pain.

The primary aim of this study was to synthesize and evaluate the existing evidence on the efficacy and safety of acupuncture in the treatment of cancer-related pain through a scoping review of systematic reviews and meta-analyses. The method used was a scoping review conducted following PRISMA-ScR guidelines and the six-stage Arksey and O'Malley methodological framework. The researchers performed comprehensive searches in multiple electronic databases, including Cochrane Database, Web of Science, PubMed, Embase, and several Chinese databases, from inception through January 2022. Systematic reviews and meta-analyses examining any type of acupuncture for patients with cancer-related pain were included.

Two independent reviewers selected the studies and extracted the data, with methodological quality assessed using the AMSTAR2 tool. Only studies examining randomized or quasi-randomized clinical trials were included, ensuring a high standard of scientific evidence.

The analysis revealed encouraging results regarding the efficacy of acupuncture in managing cancer pain. All 25 included systematic reviews and meta-analyses stated that acupuncture is an effective method for the treatment of cancer-related pain. Manual acupuncture was the most frequently studied intervention, accounting for 48% of cases, followed by the combination of acupuncture with medication (28%) and auricular acupuncture (12%). Particularly important was the finding that 11 reviews specifically assessing safety confirmed that acupuncture is safe for the treatment of cancer pain.

In addition, the evidence suggests that acupuncture may be comparable to conventional medications in terms of analgesic efficacy, with the additional advantage of reducing common drug-related adverse effects such as nausea, vomiting, constipation, and dizziness. The most frequently evaluated outcomes were pain relief rate, visual analog scale pain scores, and duration of analgesia, demonstrating consistent improvements in these parameters.

For patients facing cancer-related pain, these results offer hope for an additional therapeutic option that can be integrated into the conventional treatment plan. Acupuncture may represent a particularly valuable alternative for those experiencing intolerable side effects from conventional medications or seeking to reduce their reliance on opioids. For health care professionals, the evidence suggests that acupuncture may be considered as part of a comprehensive pain management program, especially when combined with standard medical care. The demonstrated safety of acupuncture is especially relevant for oncology patients, who often already face multiple side effects from their primary treatments.

The results also indicate that different acupuncture modalities, including manual techniques, electroacupuncture, and auricular acupuncture, may offer benefits, providing flexibility in tailoring treatment to the individual patient's needs.

However, this review also identified important limitations that must be considered when interpreting the results. Most of the included studies were conducted in China, creating a significant geographic limitation that may affect the generalizability of the findings to other populations. In addition, the methodological quality of the included reviews was considered relatively low, with only two reviews rated as moderate to high quality. Another concerning aspect was that only two reviews described in detail the specific type of cancer pain studied, with most including multiple cancer types in their analyses.

This raises questions as to whether acupuncture may have variable efficacy depending on the specific cancer type and the underlying mechanism of pain. The absence of follow-up periods in most studies also limits our understanding of the long-term effects of acupuncture in cancer pain management.

In conclusion, although current evidence suggests that acupuncture is an effective and safe intervention for cancer-related pain, studies with higher methodological quality and greater geographic diversity are needed to strengthen these conclusions. Future research should focus on specific types of cancer pain, include longer follow-up periods, and be conducted in different cultural and geographic contexts. For patients considering acupuncture as a therapeutic option, it is advisable to discuss with their medical team how this therapy may be integrated into their current treatment plan, while always maintaining conventional medical care and seeking qualified, experienced clinicians in oncology acupuncture.