This study collects bibliometric data on acupuncture and cancer pain research for its review. To avoid omissions, the authors conducted the synonyms for “cancer” and “acupuncture” through the MeSH Database in PubMed. All data were collected from the online database Science Citation Index-Expanded (SCI-E) of the Web of Science (WOS). The search time was from database inception to 12 October 2022. The language was restricted to English. There were no restrictions in terms of document type, data category, or document year. The specific search strategy and results are shown in Table 1 . There were 841 original records in total, including articles, editorial materials, letters, meeting abstracts, and reviews. Finally, we imported these articles into CiteSpace for de-duplication, which removed 51 documents, and thus, 790 results were retained.

To evaluate the final corpus of 790 articles related to acupuncture for cancer pain, this study adopts a bibliometric analysis approach for its review. Bibliometrics on acupuncture and cancer pain were visualized by using CiteSpace (Version 6.1 R3), R software (version 4.2.1), the bibliometrix R package, VOSviewer (Version 1.6.18), and Microsoft Excel 2019. Two researchers independently completed the literature selection, data extraction, and analysis to ensure the reliability of the results. CiteSpace was used for co-authorship network of countries, institutions, authors, cited journals, and references. In order to have a more comprehensive understanding of topics and research frontiers in this field, we used the bibliometrix R package and VOSviewer to analyze keywords at the same time.

The parameters of CiteSpace were set as follows: time slices were 1985-2022, the number of years in each slice was 1, the term source was selected for all selections, and Pruning was Pathfinder and Pruning sliced Networks.

Based on the above search methods and data processing, a total of 790 publications were obtained, which were published from 1985 to 2022. There were 584 articles (73.92%) and 208 reviews (26.33%) among the 790 included documents, averaging 21 publications per year. The annual distribution of the number of publications is shown in Figure 1 , showing an increasing growth trend. Before 2005, the annual number of research articles on acupuncture for cancer pain was less than 10 documents. Since then, the publications of related literature on acupuncture and cancer pain showed a small fluctuating upward trend, reaching three peaks in 2014, 2018, and 2021. And 2021 (97 publications, 12.28%) was the most prolific year for publications. To ensure whether the growth of publications on studies of acupuncture for cancer pain conformed to Price’s law, the acquired data were exponentially adjusted and linearly fitted. We obtain the equation y = -1.6+2.6e^{((x-1985)/6.47)}(R² = 0.98)from its exponential curve, with the result of good fitting. As a result, the continuous increase in publications over time indicates that the cancer pain aspect of acupuncture therapy is attracting increasing attention, which can provide recommendations for future research.

A country collaboration network map was generated by CiteSpace ( Figure 2 ). The top 5 most productive countries are presented in Table 2 . This research involved a set of 54 countries with 118 links. The countries with the most publications were mainly China and the United States. China contributed the highest number of articles (288, 36.46% of all articles), followed by the United States (281, 35.57%), South Korea (67, 8.49%), and England (53, 6.71%). The top five countries by centrality were the United States (0.42), China (0.26), Japan (0.15), Italy (0.09) and Saudi Arabia (0.09). As seen from it, the United States and China have published a large amount of relevant literatures and established collaborative relationships with many countries. Meanwhile, the United States also showed the highest centrality.

According to the CiteSpace, a total of 458 institutions were involved in this field ( Figure 3 ). The 10 institutions with the highest number of articles were obtained ( Table 3 ). Mem Sloan Kettering Canc Ctr (38 records, 4.81% of all articles) contributed the most publications, followed by Beijing Univ Chinese Med (28, 3.54%), Kyung Hee Univ (25, 3.16%), Guangzhou Univ Chinese Med (18, 2.28%), and Nanjing Univ Chinese Med (17, 2.15%). Beijing Univ Chinese Med showed the highest centrality (0.19). Thus, we can see institutions with the most publications and high centrality are mainly distributed in China and the the United States. The purple circle around the nodes reflects the centrality of the network, indicating that Mem Sloan Kettering Canc Ctr and Beijing Univ Chinese Med played a pivotal role in the cooperative relationships among institutions.

The CiteSpace software was used to generate a co-author map containing 671 nodes and 1233 links ( Table 4 ; Figure 4 ). In terms of the number of published papers, MAO J was the most prolific author, with 23 articles (2.91%), followed by WANG Y (22, 2.78%), LEE J (18, 2.28%) and LIU Y (17, 2.15%). LEE J and DENG G showed the highest centrality, each with the centrality of 0.09. By observing the visualization map, we could find the authors with more publications and higher central position tend to cooperate closely with other authors.

An author co-citation map was generated displaying 969 nodes and 3444 links ( Table 5 ; Figure 5 ). The top 5 most cited authors were Molassiotis A (102), Vickers AJ (101), Ernst E (93), Lu WD (93), and Hershman DL (92). The top 5 authors in centrality were Cassileth BR (0.2), Ernst E (0.19), Vickers AJ (0.1), Molassiotis A (0.09), and, Shen JN (0.09).

In total, 297 academic journals published papers about acupuncture for cancer pain. Table 6 lists the top 10 most popular journals contributing to articles on acupuncture and cancer pain topics, and shows the countries of origin and the impact factor of the top 10 journals. The top 10 journals published about 34.43% of the documents in the field. Among them, the average impact factor (IF) was 7.5572. Evid-Based Compl Alt was the leading journal, publishing the most papers (42 articles, England), followed by Integr Cancer Ther (40 articles, United States), Medicine (33 articles, United States), Supportive Care In Cancer (30 articles, United States), J Altern Complem Med (30 articles, United States), J Pain Symptom Manag (28 articles, United States), Acupuncture In Medicine (26 articles, England), Complement Ther Med (15 articles, England), J Clin Oncol (14 articles, United States), and Acupuncture Electro (14 articles, United States). The impact factor (IF) of Evid-Based Compl Alt (the most published journal) was 2.650 (2021), and the H-index was 72. Among the top 10 journals, the journal with the highest IF (50.717), which also had the highest H-index (494), was J Clin Oncol from the United States. It indicates that the articles published in this journal are influential in the field of acupuncture for cancer pain.

Table 7 and Figure 6 present the top 5 cited journals on acupuncture for cancer pain research. J Clin Oncol was cited in the most journals (391 counts), followed by Pain (360 counts). The highest citation counts of this journal may be due to it being the journal with the highest IF and the highest H-index. This also provides a direction for us to find related articles in the future. Evid-Based Compl Alt ranked third, with 324 counts. The fourth and fifth, with more than 250 citations, were Acupunct MED (285 counts) and Support Care Cancer (275 counts), respectively. A node represents a journal, the purple ring outside the node indicates the size of the centrality of the journal. Brit MED J has the highest centrality (0.15).

We used CiteSpace to obtain a reference co-citation map related to studies on acupuncture for cancer pain ( Figure 7 ), with 916 nodes and 2522 links. Table 8 enumerates the basic information of the top 10 most cited references. These highly cited studies were mainly published between 2013 and 2020. The most cited reference was Hershman DL’s paper, which was a randomized clinical trial (RCT) of the acupuncture effects on joint pain related to aromatase inhibitors among women with early-stage breast cancer, published in JAMA in 2018. It was cited 41 times. Chiu HY (2017) wrote the second most highly cited paper, with 37 citations. He YH (2020) wrote a systematic review, ranked third, with 33 citations. The fourth position was occupied by Garcia MK (2013), with 29 citations. Followed by Mao JJ (2014), Paley CA (2015), and Vickers AJ (2018), with 23 citations. A total of 24 clusters were obtained. The largest cluster was “pain management” which contains 104 references. The color of the cluster “complementary medicine”, “nonpharmacological management”, and “insured cancer patient” were red, indicating the latest research direction of research on acupuncture in treating cancer pain.

Co-occurrence analysis of keywords can identify research hotspots and trends. We analyzed a total of 90 keywords among 2937 keywords related to the research of acupuncture for cancer pain that were identified as having occurred more than fifteen times. The top 90 keywords are visualized in Figure 8A , showing that predominant words were divided into three clusters, represented by three colors (red, green, and blue).

We can see a visualization of each cluster of keywords over time ( Figures 8B–D ). Cluster 1 refers to acupuncture therapy method for cancer pain, indicated by red, with the main keywords of acupuncture, management and breast cancer. Cluster 2 refers to electroacupuncture therapy method for cancer pain, indicated by green, with the main keywords of electroacupuncture, induced peripheral neuropathy and postoperative pain. Cluster 3 refers to disease, indicated by blue, with the main keywords of chemotherapy, chemotherapy induced periphera, neurotoxicity, and multiple myeloma, which were the latest topics. The development trend and strategic coordinate map are shown in Figure 9 . The high-occurrence words ( Figures 9A, B ) include acupuncture (239 times), pain (199 times), management (139 times), quality of life (107 times), electroacupuncture (100 times), breast cancer (82 times), therapy (77 times), cancer (66 times), women (61 times), complementary (60 times). It can be seen that the covered groups with the need to treat cancer pain by acupuncture mainly existed in women, and their negative emotions were mainly anxiety and depression. Acupuncture was most likely to be considered as an alternative therapy to provide effective palliative treatment for cancer pain patients, and improve their quality of life. The cancer pain categories treated by acupuncture were mainly breast pain, neuropathic pain, and low back pain, which were characterized by chronic pain. In addition, we can also see that these treatments were mostly achieved through RCTs. Figure 9C shows that the frequency of the above top 10 keywords increased over time. The keyword “acupuncture” grew the fastest, followed by “breast cancer”. Through the thematic map of keywords ( Figure 9D ), internal organ, o-ring test, and clinical application were highly developed and isolated themes; acupuncture point wes emerging or declining themes; acupuncture, pain; electroacupuncture were basic and transversal themes. In addition, we can predict that neuropathic pain, mechanism, expression, management, quality of life, and breast cancer will be the research trends.

Since 2005, the annual publication output in this field has increased in a steady fashion. The publication output in 2021 was the highest, accounting for 12.28% of all the included studies. It can be seen that acupuncture on cancer pain has attracted more and more attention, and various countries have begun to using acupuncture to treat patients with cancer pain. The reason why acupuncture attracts more and more attention to this field is that, on the one hand, the development of the modern medicine is more and more mature and the patients’ quality of life is concerned. On the other hand, the reason may be the widely use of acupuncture in medical fields has been proved to be effective.

China was the country with the largest number of publications, but the United States had a high centrality of 0.42, indicating that most countries in this field had direct and indirect cooperation with the United States. The institutions with the most publications were in the United States. And the institution with the largest number of publications in China is Beijing Univ Chinese Med. It may be concluded that Chinese researchers, with the advantage of the long history use of acupuncture, are equipped to conduct more studies and publish more literature, while western researchers are more influential in the study of cancer pain. According to the analysis of publishing institutions, the first and second institution were Mem Sloan Kettering Canc Ctr and Beijing Univ Chinese Med respectively, both of which have very strong comprehensive strengths. Mem Sloan Kettering Canc Ctr is the largest private cancer research center in the world, making a significant contribution to the understanding, diagnosis and treatment of cancer. Beijing Univ Chinese Med is the most important medical innovation research base in China, training a large number of senior medical and health personnel. These results suggest that the two institutions mentioned above, may significantly influence the direction of studies in this field and participate in the strongest cooperation globally.

Although J Clin Oncol ranked ninth with 28 published articles, it had the most citations with the highest IF (50.717) and H-index (494) at the same time, indicating that this journal is very influential in this field, which can provide inspiration for future research. MAO J, a doctor from Mem Sloan Kettering Canc Ctr, who had the largest number of publications (23, 2.91%), is a pioneer in the field of acupuncture in the treatment of cancer pain. With the increase of cancer incidence and mortality, MAO J believed that the current cancer care had been challenged. Therefore, he proposed an integrative medicine (TCIM) including acupuncture and massage, to alleviate cancer symptoms or treatment-related adverse reactions such as pain, insomnia and fatigue (19). The author with the highest cited frequency is Molassiotis A, whose most cited paper is a RCT published in Support Care Cancer in 2002, which focused on adjuvant intervention to improve the standards of care for cancer patients with side effects of chemotherapy (20).

Keywords and references reflect the content of the research, which is helpful to identify hotspots and frontiers from their frequency, centrality, and clustering distribution.

Based on the co-occurrence map of keywords and references map, it can be determined that acupuncture and electroacupuncture (EA) may be the main therapeutic therapies for cancer pain. In addition, the management of cancer pain probably have received the greatest concern from researchers in this field. We can also infer that studies on the treatment of cancer pain with acupuncture have covered a variety of types, including breast pain, arthralgia, neuropathic pain, and low back pain.