Efficacy and Safety of Acupuncture-Moxibustion Therapy on Chemotherapy-Induced Leukopenia: A Systematic Review and Meta-Analysis

Background Acupuncture-moxibustion therapy (AMT), as an integral part of complementary and alternative medicine, has been used for centuries in treatment of numerous diseases. Nevertheless, there is no available supportive evidence on the efficacy and safety of acupuncture-moxibustion therapy in patients with chemotherapy-induced leukopenia (CIL). The purpose of this study is to evaluate the efficacy and safety of acupuncture-moxibustion therapy in treating chemotherapy-induced leukopenia. Methods Relevant studies were searched in nine databases up to September 19, 2020. Two reviewers independently screened the studies for eligibility, extracted data, and assessed the methodological quality of selected studies. Meta-analysis of the pooled mean difference (MD) and risk ratio (RR) with their respective 95% confidence intervals (CI) were calculated. Results 17 studies (1206 patients) were included, and the overall quality of the included studies was moderate. In comparison with medical therapy, AMT has a better clinical efficacy for CIL (RR, 1.24; 95% CI, 1.17-1.32; P < 0.00001) and presents advantages in increasing leukocyte count (MD, 1.10; 95% CI, 0.67–1.53; P < 0.00001). Also, the statistical results show that AMT performs better in improving the CIL patients' Karnofsky performance score (MD, 5.92; 95% CI, 3.03–8.81; P < 0.00001). Conclusion This systematic review and meta-analysis provides updated evidence that AMT is a safe and effective alternative for the patients who suffered from CIL.


Introduction
Nowadays, cancer imposes a major threat to human lives with high incidence and mortality. ere were about 24.5 million cancer incident cases and 9.6 million deaths around the world in 2017 [1]. Along with radiation and surgery, chemotherapy remains one of the three standard therapeutic approaches against kinds of cancers. However, chemotherapy drugs are generally related to multiple side effects on patients, of which leukopenia (48.9%) is the most notable [2]. Leukopenia during cytotoxic chemotherapy is associated with an unfavorable prognosis in patients with breast cancer, colorectal cancer, and small-cell lung cancer [3]. Once chemotherapy-induced leukopenia occurs, it would not only hinders patients from completing prescribed treatment on time but also affects the quality of life (QoL), and even lead to serious infection and death. Currently, hematopoietic cytokine granulocyte, colony-stimulating factor (G-CSF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) are widely employed to accelerate recovery for patients with CIL via accelerating neutrophil recovery and regulating granulopoiesis [4]. Although this adjuvant therapy is indeed effective with a rapid onset, the evidence of long-term efficacy and safety has not yet been determined. Besides, due to the high price, it exacerbates the cost of hospitalization and imposes additional economic burden for the families of cancer patients. Hence, effective and safe therapeutic strategies to reverse CIL without supporting tumor progression are urgently desired.
As an integral component of traditional Chinese medicine (TCM), acupuncture-moxibustion therapy is one of the most popular methods for complementing medicines in China and other East Asian countries. It is an external therapy to prevent and treat disease by stimulating particular acupoints on the human body with special needles or burning moxa [5]. In theory, acupuncture and moxibustion are two sides of the same coin, and in application, these treatments are supplementary to each other. Both acupuncture and moxibustion are based on the theory of channels and collaterals in Chinese medicine. eir effects are exerted by the stimulation of acupuncture points at specific anatomic locations on the body surface or tender points known as Ashi points, usually by needles or ignited moxa floss. e efficacy of AMT has been widely demonstrated in type 2 diabetes, dysenteric diarrhea, hepatogastrointestinal diseases, and many other diseases [6][7][8][9]. To investigate the therapeutic effect of AMT on CIL, many randomized clinical trials have been conducted in recent years. An exploratory meta-analysis [10] focused on chemotherapy-induced leukopenia published in 2007 demonstrated that acupoint stimulation promoted an increase in leukocyte count. In contrast, Chio et al. [11] argued that the evidence of the moxibustion efficacy in treating chemotherapy-induced leukopenia was insufficient to draw firm conclusions. To date, there continues to be no consensus about whether acupuncture-moxibustion therapy could be an attractive alternative for CIL. erefore, this systematic review and meta-analysis was conducted to assess the efficacy and safety of AMT for the clinical treatment of CIL, so as to provide evidence for clinical practice.

Methods
is systematic review and meta-analysis was performed in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) schema and was registered at PROSPERO under registration number CRD42020152517 [12].

Literature Search Strategy.
A comprehensive search was carried out in PubMed, Embase, Scopus, Web of Sciences, the Cochrane Library (CENTRAL), and four Chinese databases (Chinese Biomedical Database, Chongqing VIP Information, China National Knowledge Infrastructure, and WanFang Data) from their inception up to September 19, 2020 without language limitation. e search strategy consisted of Medical Subject Heading (Mesh) terms and free-text terms with logical operators. We performed an initial search of PubMed as follows: "Neoplasms" (Mesh) AND "Drug erapy" (Mesh) AND "Leukopenia" (Mesh) AND "Acupuncture erapy" (Mesh) AND "Moxibustion" (Mesh). e exploration of grey literature and handchecking of key journals were completed to identify potentially relevant trials [13]. We also manually searched the references of the retrieved articles. EndNote X9 (Clarivate Analytics, 2018, Philadelphia, Pennsylvania) was utilized to store and manage all the literature downloaded from databases.

Study Selection.
Studies were eligible in this metaanalysis, which met the following criteria. Study participant: the patient undergoing chemotherapy and diagnosed with leukopenia under clear criteria: (i) the total number of leukocytes remained below 4.0 or (ii) WHO grading standards. Study intervention: the patient in the experimental group was treated with acupuncture-moxibustion therapy.
ere were no restrictions on the selection of acupuncture points and the course of treatment. Comparison treatment: (i) conventional leukocyte-enhancing drugs (e.g., leucogen tablets, berbamine hydrochloride tablets, and rhG-CSF injection) or (ii) no comparator treatment. Study outcome: (i) primary measures: leukocyte count and total effective rate. Total effective rate � markedly effective + effective. Markedly effective: the count of leukocyte recovers to a normal value of 4.0 × 10 9 /L; effective: although the leukocyte count did not return normal, it increased (0.5∼1.0) × 10 9 /L; and invalid: no significant change in leukocyte count. (ii) Secondary measures: Karnofsky's index of performance status. Study design: randomized controlled trial. Additionally, the exclusion criteria included the following: (i) full-text not be obtained; (ii) incomplete data and the unclear outcome effect; (iii) duplicate publication; and (iv) case report, expert experience, review article, and other nonrandomized control trials.
After deleting the duplications, two reviewers (HMJ and YTZ) independently screened the title and abstract of studies according to the inclusion and exclusion criteria. en, a full-text screening was performed by the same two reviewers. Any disagreement during study selection was resolved by consulting a third senior reviewer (YYX).

Data Collection and Quality Assessment.
We designed a data extraction sheet to record related characteristics from the included articles, including diagnostic criteria, sample size, outcome measures, and treatment details.
is was performed and proofread after completion by two authors (HMJ and YTZ) independently to ensure the accuracy of the extracted data. And then, they continued to assess the quality of included studies. e methodological quality was evaluated using the Cochrane risk of bias tool to assess the risk of bias in each included trial. e contents include six domains: random sequence generation, allocation concealment, blinding, integrity of outcome data, selective reporting, and other bias. Each item was rated three levels as low risk, high risk, and uncertain risk for insufficient information. Any disagreement in the assessment process was resolved through the third reviewer (YQF).

Statistical Analysis.
All statistical analyses were performed using Review Manager software (version 5.3, Cochrane Collaboration, 2014, Copenhagen, Denmark). e risk ratios (RR) along with the corresponding 95% confidence intervals (95% CI) were calculated for dichotomous data, and mean differences (MD) with 95% CIs were calculated for continuous data. Statistical heterogeneity between studies was assessed by the I-square statistic (<25%, low heterogeneity; 25%-50%, moderate heterogeneity; and >50%, strong heterogeneity). A random-effects (RE) model was selected when heterogeneity existed significantly; otherwise, a fixed-effects (FE) model was preferred. In this meta-analysis, subgroup analysis and the sensitivity test were also conducted to explain the source of heterogeneity. Funnel plots were introduced to detect the existence of potential publication bias.

Study Characteristics.
A total of 17 trials with 1206 participants were selected and varied widely in sample size (32-160 participants). All the included studies were conducted in China and published from 2010 to 2019. All patients fulfilled the diagnostic criteria of chemotherapyinduced leukopenia, with one study only confirmed in the title and abstract. Twelve studies adopted acupuncture therapy, while five studies relied on moxibustion therapy as the treatment of CIL. e primary outcome measures, i.e., the leukocyte count or clinical efficacy, could be obtained in all studies. e main characteristics and the specific interventions of each identified study are presented in Table 1. Figure 2 presents the quality assessment results of all eligible trials. e general quality of these trials was rated as moderate, since the relevant information was often missing or incomplete. All but one study [30] clearly mentioned the random allocation of participants to groups, in which 12 studies (70.1%) described the specific random methods [14, 16-18, 20, 22-24, 26-29]. Only one study adequately reported the allocation concealment, which was implemented using sealed opaque envelopes [16]. e risk of bias was uncertain for performance blinding of participants, personnel, and outcome assessors in most included studies. One study did not report the planned secondary outcomes of leukocyte count, so was ranked as high risk of reporting bias [19]. Most of studies (94.1%) were judged as low risk of bias from incomplete data, and no other potential sources of bias were detected.

Karnofsky Performance
Score. Four studies [15,26,28,29] with a total of 292 participants provided data on the Karnofsky performance score. e higher score represents the better functional health status. As shown in Figure 7, the results revealed that AMT performs better in improving health conditions (MD, 5.92; 95% CI, 3.03-8.81; P < 0.00001). Besides, we found that heterogeneity may originate from one study [15], and the heterogeneity disappeared after removing this single study.

Adverse Events.
Safety outcome refers to the adverse events, such as allergic reaction, local responses (rash and scald), liver, and kidney injury, during the study. Among the conducted trials, safety outcomes were mentioned in five studies [15,16,18,25,28], four of which indicated that no adverse events had occurred. Explicitly, Fan [16] reported five (17%) participants in the control group and four (13%) in the experimental group had minor adverse events. e remaining 12 trials failed to assess safety for AMT treatment.

Sensitivity Analysis.
To evaluate the robustness of pooled results, we performed the sensitivity analysis by omitting each study sequentially. Under the leave-one-out approach analysis, our results did not change noticeably.

Publication Bias.
Publication bias was observed visually using funnel plot analyses. In this meta-analysis, the funnel Evidence-Based Complementary and Alternative Medicine plot for the total effective rate shaped with bilateral symmetry, indicating a lack of publication bias ( Figure 8).

Main Findings.
As the meta-analysis reveals, acupuncture-moxibustion therapy could be an alternative treatment for chemotherapy-related leukopenia. From the clinical perspective, AMT could indeed increase the number of leukocyte and improve health status. Furthermore, there were almost no serious adverse events and treatment-related safety issues. We conducted subgroup analyses for each primary outcome, and the results suggested that different choices of AMT types and duration of treatment might be sources of heterogeneity. Based on our summaries about specific interventions of included studies, the most commonly used acupoints in treating CIL were Zusanli (ST36) and Guanyuan (CV4).

4.2.
Possible Rationale of AMT for CIL. Chemotherapy-induced leukopenia is regarded as a potential serious adverse event, defined as white blood cell (WBC) count less than 4.0 × 10 9 /L during the course of chemotherapy. Patients with CIL typically present symptoms of loss of appetite, fatigue, insomnia, and dizziness. Based on the theory of traditional Chinese medicine (TCM), CIL belongs to the category of consumptive disease, owing to the exhaustion of genuine qi in the zang-fu viscera and the insufficiency of kidney essence and qi-blood. Researchers believe that there is an intimate association between the occurrence of malignant tumors and the deficiency of genuine qi. During attacking the cancer cells, chemotherapeutics also damaged the function of zang-fu viscera and qi-blood, leading to CIL. According to the theory of TCM and meridian, acupuncture-moxibustion is an ancient therapeutic modality that may be traced back more than 3500 years in China. rough meridian conduction, acupuncture-moxibustion therapy stimulates acupoints to strengthen the condition of zang-fu viscera and immune function, supporting genuine qi to improve symptoms of consumption. At the same time, some studies have attempted to further explore the molecular biological mechanism of acupuncture-moxibustion for relieving chemotherapy-induced leukopenia. By increasing the level of Studies included in qualitative synthesis (n = 17) Studies included in quantitative synthesis (meta-analysis) (n = 17)  serum GM-CSF and G-CSF, acupuncture-moxibustion could prompt the proliferation and maturation of marrow hematopoietic cells, which favor the recovery of hematopoiesis function and reduce myelosuppression from chemotherapeutic agents [15]. Similarly, acupuncturemoxibustion upregulated the expression of cyclin D1 protein  Evidence-Based Complementary and Alternative Medicine to accelerate the cell cycle progression, increasing DNA synthesis and enhancing DNA repair capacity. erefore, leukocyte levels in the peripheral blood were elevated slowly but steadily under the influence of the protective effects on bone marrow cells by acupuncture-moxibustion stimulation [31].

Comparison of Previous Meta-Analysis.
To the best of our knowledge, the present systematic review and metaanalysis is the first study on the effect and safety of AMT in treating CIL. Distinguished from the previous study [10,11], we included twenty-one eligible trials with larger sample size, making the obtained conclusions more convincing than those of Lu et al. [10]. In addition, several different methods, including the laboratory indicator and clinical symptoms evaluation, were applied to estimate the therapeutic effect of AMT. From various aspects, this embodies a significant role of AMT in improving the quality of life and alleviating chemotherapy side effects. Also, it is worth pointing out that we take adverse events related to AMT into account, which were previously ignored by Choi et al. [11].

Limitations.
First, even though comprehensive literature search was performed, we only identified studies published in Chinese. So, the potential language bias might be caused. Second, there were no uniform standards for the selection of acupoints of patients with leukopenia after chemotherapy. By combining experience in clinical practice, clinicians might have preferences for different acupoints regimens. Finally, the methodological quality of included trials was deemed weak to moderate. Hence, interpretations of our findings should be taken with caution.

Conclusion
In summary, this is an updated systematic review and metaanalysis, revealing that the AMT, as a nonpharmaceutical intervention, could be an effective and safe alternative for patients undergoing CIL. Despite limitations, the study provides the direction and basis for future research. Highquality randomized controlled trials are warranted to further validate current results, offering more confident conclusions for clinical practices.

Data Availability
All articles retained for this review were made available to the public through PubMed, Embase, the Cochrane Library, Scopus, Web of Sciences, Chinese BioMedical Database, Chongqing VIP Information, China National Knowledge Infrastructure, and WanFang Data. All data analysed in this study are included in the published articles.
Disclosure e funding organizations played no role in the design of the study and data collection, analysis, or interpretation. ey also were not involved in the writing of the manuscript.

Conflicts of Interest
e authors declare that they have no conflicts of interest.  Evidence-Based Complementary and Alternative Medicine