Chinese herbal formulas alleviated depression in breast cancer patients: A meta-analysis, network pharmacology and experimental validation

Abstract

BACKGROUND

Depression represents a frequent comorbidity in breast cancer patients. However, many antidepressants have a certain degree of adverse reactions and decline patients’ compliance to conventional therapies. Chinese herbal formulas (CHF), with its long-standing application in mood disorders, offers a potential alternative. Nevertheless, comprehensive evidence regarding its effectiveness specifically for depression in breast cancer populations remains limited.

AIM

To systematically evaluate the efficacy of CHF interventions for depression in breast cancer patients and explore the potential mechanisms.

METHODS

We systematically searched four English databases (PubMed, EMBASE, the Cochrane Library, PsycINFO) and four Chinese databases (CNKI, CBM, VIP, Wanfang) from their inception through June 2024. The investigation focused on CHF’s effects on psychological outcomes [depression and quality of life (QOL)], neurochemical parameters (serotonin, norepinephrine, and dopamine levels) and immunological indicators (CD4+ and CD8+ T lymphocyte counts). Network pharmacology and experimental analysis of clinical samples were employed to elucidate the mechanisms of the core formula Si-Ni-San (SNS).

RESULTS

Pooled data from 20 randomized trials (n = 1607) demonstrated CHF’s superiority over antidepressants in reducing Hamilton Depression Rating Scale scores (mean difference = -5.33, 95% confidence interval: -6.93 to -3.73, P < 0.05) and enhancing QOL (mean difference = 9.13, 95% confidence interval: 6.69-11.57, P < 0.05). CHF significantly elevated monoamine neurotransmitter levels (all P < 0.05) and CD4+ T cell counts (P < 0.05), with no effect on CD8+ subsets. Subgroup analysis revealed enhanced efficacy with interventions ≥ 4 weeks. Safety profiles favored CHF, with fewer adverse events vs antidepressants. Network pharmacology analysis suggested that SNS may exert its effects by modulating immune responses and serotonergic synapse pathways. Experimental analysis of clinical samples further indicated that the antidepressant effects of SNS may be mediated through the regulation of CD4+ T cells and rebalancing of neurotransmitter, tryptophan metabolism.

CONCLUSION

This systematic review establishes CHF as an effective and safe intervention for depression in breast cancer patients, with benefits extending to QOL, monoamine neurotransmitter levels and immunological parameters. Moreover, SNS represents a promising complementary therapy with multi-pathway mechanisms of action, particularly involving immune and metabolic pathways.

Key Words: Meta-analysis; Traditional Chinese medicine; Breast cancer; Depression; Si-Ni-San

Core Tip: In present study, we found that Chinese herbal formulas outperformed antidepressants in reducing depression and improving quality of life, significantly elevated monoamine neurotransmitter levels, and selectively increased CD4+ T-cell counts. Network pharmacology revealed that Si-Ni-San may modulate immune responses and serotonergic synapses, while experimental validation indicated involvement of CD4+ T cells and rebalancing of neurotransmitter, tryptophan metabolism. These results advocate for the integration of Chinese herbal formulas especially Si-Ni-San into integrative care protocols for breast cancer-related depression and underscore the need for further mechanistic and clinical investigation.

INTRODUCTION

Breast cancer constitutes a significant public health concern globally, representing the most prevalent cancer diagnosis and a primary contributor to cancer-associated deaths among women. Current epidemiological reports indicate approximately 2.33 million new cases and 664000 fatalities annually[1]. Although developments in screening technologies and treatment modalities have enhanced survival outcomes[2], marked inequalities in mortality rates persist across different healthcare settings[3]. The condition’s impact transcends clinical parameters, generating considerable socioeconomic consequences as reflected by its prominent position among leading causes of disability-adjusted life years in multiple nations[4]. In response, the World Health Organization’s Global Breast Cancer Initiative has established ambitious targets to reduce mortality through 2040[5].

The psychological burden accompanying breast cancer diagnosis and treatment is substantial. Compared to the general population, depression occurs 3-5 times more frequently in cancer population than in the general community[6,7]. Clinical investigations report that nearly 50% of patients develop clinically relevant depressive symptoms within the initial treatment phase[8]. Meta-analytic evidence confirms a pooled depression prevalence of 32.2% among breast cancer patients[6], with mood disturbances independently predicting worse oncological outcomes. These affective disturbances demonstrate independent prognostic significance, correlating with elevated risks of cancer recurrence (24% increase) and disease-specific mortality (29% increase)[9]. This association was attributed to a variety of biological and behavioral mechanisms. It was reported that depression could affect immune and endocrine systems directly[10]. The underlying pathophysiology also involves complex interactions between neuroendocrine dysfunction, particularly hypothalamic-pituitary-adrenal axis dysregulation[11]. Additionally, depression even in subthreshold manifestations, is associated with maladaptive lifestyle habits and poor adherence to medical appointments and therapies[12,13], which may indirectly influence cancer progression. Therefore, to enhance the prognosis and overall survival of breast cancer patients, it is imperative to explore strategies for alleviating depression and optimizing long-term clinical outcomes.

At present, both non-pharmacological treatments and antidepressants are recommended as therapeutic approaches. However, psychological specialists may lack professional training in working with cancer patients, and the antidepressants may worsen existing symptoms and interact with chemotherapy agents[14]. In addition, previous studies indicated that antidepressants were found with low-certainty evidence for their application in cancer patients[15]. Traditional Chinese medicine (TCM) has long been appreciated to treat depression, particularly in Asia. Notably, its holistic, multi-ingredients and multi-targets nature fits well with modern systemic medicine. Chinese herbal formulas (CHF) usually combine two or more medicines to create synergistic effects and minimize toxicity, much like modern therapeutic strategies that require multiple drugs[16,17]. Xiao-Yao-San, a commonly employed anti-depression formula, has been shown to meliorate depressive-like behaviors induced by gut microbiota dysbiosis by regulating the gut microbiota and counteracting abnormal synaptic pruning[18]. Another anti-depression formula Si-Ni-San (SNS) has demonstrated antidepressant effects in various clinical contexts[19-23], while emerging studies have further underscored its potential in suppressing the growth and metastasis of breast cancer triggered by chronic psychological stress, potentially through interactions with the central nervous system, cancer stem cells and bile acids metabolism[24-26]. As the field of CHF continues to be explored, a variety of active ingredients and components with notable antidepressant properties have been identified. Saikosaponin A, a pivotal bioactive constituent derived from Radix Bupleuri, has been proposed to exert antidepressant efficacy by augmenting the expression level of proline-rich transmembrane protein 2 and dopamine (DA) levels content within the hippocampus[27]. Those CHF and ingredients appear to exert their effects by modulating various systems[28], which offer novel insights into the therapeutic mechanism underpinning the use of CHF for the management of depression. Therefore, the leading organizations in the field, such as the American Cancer Society, recommended integrative therapies for symptoms management during breast cancer treatment[29]. However, a systematic review is necessary to explore the therapeutic efficacy and safety of CHF for depression treatment in breast cancer patients.

To address this gap, we conducted a systematic review and meta-analysis to determine whether CHF therapy is beneficial in relieving depression among breast cancer patients. In present study, we found that CHF outperformed antidepressants in reducing depression and improving quality of life (QOL), significantly elevated monoamine neurotransmitter levels, and selectively increased CD4+ T-cell counts. Network pharmacology revealed that SNS may modulate immune responses and serotonergic synapses, while experimental validation indicated involvement of CD4+ T cells and rebalancing of neurotransmitter, tryptophan metabolism. These results advocate for the integration of CHF especially SNS into integrative care protocols for breast cancer-related depression and underscore the need for further mechanistic and clinical investigation.

MATERIALS AND METHODS

Protocol and guidance

This systematic review and meta-analysis adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The study protocol was prospectively registered in the PROSPERO international prospective register of systematic reviews (Registration No. CRD42024555279).

Search strategy

An extensive literature search was conducted across eight databases from inception through June 1, 2024, including both international databases (PubMed, EMBASE, Cochrane Library, and PsycINFO) and Chinese databases (CBM, CNKI, VIP, and Wanfang). Supplementary searches included: Manual screening of reference lists from eligible studies and relevant reviews, conference proceedings for unpublished data, existing systematic reviews for additional trials.

The search strategy incorporated three key domains: (1) Population: Breast cancer patients with depression (breast cancer, breast neoplasms, depression, and mental health); (2) Intervention: CHF therapies (TCM, Chinese herbal medicine, decoctions, formulas); and (3) Study design: Randomized controlled trials (RCTs). Two of us (Hong SC and Du YY) independently reviewed the abstracts and titles of preliminary literature, or the full texts as necessary, to establish the eligibility of the studies. Two independent reviewers (Hong SC and Du YY) screened titles/abstracts and full texts when necessary. Complete search terms are provided in Supplementary Tables 1 and 2.

Inclusion and exclusion criteria

Studies were included if they met the following criteria: (1) Participants: Individuals histopathologically diagnosed with breast cancer and meeting depression criteria as defined by the Diagnostic and Statistical Manual of Mental Disorders Fourth Edition, Research Diagnostic Criteria, International Statistical Classification of Diseases and Related Health Problems, or Chinese Classification of Mental Disorders Third Edition Revised; (2) Interventions and comparisons: The treatment group received CHF, and the control groups were categorized as either “antidepressant” or “no intervention”, the latter denoting the absence of any specific antidepressant intervention; (3) Outcome measures: Primary outcomes of depression included Hamilton Depression Rating Scale (HAMD) or Self-rating Depression Scale (SDS) values, and secondary outcomes encompassed QOL, serum levels of 5-hydroxytryptamine (5-HT), DA, and norepinephrine (NE), as well as immune function indices (CD4+, CD8+ T lymphocytes); and (4) Study design: Published RCTs. Exclusion criteria include: (1) Duplicate publications; (2) Studies lacking relevant outcome data; (3) Unavailable primary data after author contact; and (4) Non-English/Chinese publications.

The PRISMA criteria were adhered to[30]. EndNote 20 was utilized for literature management. Two researchers (Hong SC and Du YY) independently screened article titles and abstracts. Any disagreements during screening were resolved in consultation with another researcher (Wang GB). Relevant information was independently extracted and cross-checked by two researchers (Hong SC and Du YY), including: (1) Basic information on the article: Author’s name, year of publication, study type, and sample size; (2) Patient characteristics: Age, disease course; and (3) Treatment outcomes: Clinical intervention, intervention time, and outcomes. Disagreements were solved by discussion or consulting a third-party opinion (Wang ZY).

Data extraction and risk of bias assessment

The data extraction process was conducted systematically by two independent reviewers who collected comprehensive information from each included study according to a predefined protocol. This encompassed four main categories of data: (1) Bibliographic details including authorship and publication year; (2) Methodological characteristics such as study design, sample size, intervention protocols for both treatment and control groups, specified outcome measures, and duration of intervention; (3) Demographic information about participants including age range and sex distribution; and (4) Contextual details regarding study location and healthcare setting. Any discrepancies between reviewers during this process were resolved through discussion and, when necessary, arbitration by a third senior investigator.

For quality assessment, we employed the Cochrane Risk of Bias tool (implemented in RevMan version 5.4) to rigorously evaluate each study across six critical methodological domains: Randomization procedures, allocation concealment, blinding of participants and personnel, blinding of outcome assessors, completeness of outcome data, and potential selective reporting. Each study underwent independent duplicate evaluation by two team members, with a third reviewer consulted to reach consensus on final classifications of low, high, or unclear risk of bias for each domain. This comprehensive approach ensured robust and standardized assessment of study quality throughout our systematic review.

Study quality

The Grading of Recommendations Assessment, Development and Evaluation system and software (GRADE Pro GDT) were employed to rate the quality of all included RCTs. The overall certainty of evidence was categorized into four levels: High, moderate, low, or very low, based on the five GRADE domains. Any disagreements were resolved through consultation with a third researcher.

Data synthesis

Review Manager software (version 5.4.1) was used for the meta-analysis. For continuous variables, effect estimates were calculated as mean differences (MD) with 95% confidence intervals (CI) presented in forest plots. If meta-analysis was not feasible, descriptive analysis was performed. A random-effects model was used to synthesize evidence. Sensitivity or subgroup analysis was conducted to identify the sources of heterogeneity. Sensitivity analysis was performed by sequentially deleting studies to ensure result stability. Subgroup analysis was based on the type of intervention (antidepressants or no intervention), antidepressant type, and CHF intervention duration (≤ 4 weeks or > 4 weeks). Publication bias was assessed using funnel plots when at least 10 trials were included. Statistical significance was set at P < 0.05.

Network pharmacology

The potential active ingredients from the top five herbs were identified using the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (CHFSP, https://CHFsp-e.com/CHFsp.php), applying cut-off criteria of oral bioavailability ≥ 30% and drug likeness ≥ 0.18. These ingredients were standardized using the UniProt protein database (https://www.uniprot.org). Breast cancer-related and depression-related targets were collected from the GeneCards database (https://www.genecards.org) (cut-off: Degree ≥ median). Interactions between top drug-related targets, breast cancer-related, and depression-related targets were analyzed using the STRING database (https://string-db.org), with a cut-off of a minimum interaction score of “highest confidence” (> 0.900). The results were visualized using Cytoscape 3.7.1. The intersection targets were imported into the Metascape platform for Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Visualization analysis was performed using the Bioladder tool (https://www.bioladder.cn/).

Clinical sample collection

Samples were collected from participants after 4-week SNS or placebo treatment in the previous study (ChiCTR2200065009). The original clinical trial was approved by the Ethics Committee of Guangdong Provincial Hospital of Chinese Medicine (Approval No. 2022-177-01). Written informed consent was obtained from all participants, which included consent for the secondary analysis of biospecimens for mechanistic research.

The enrolled breast cancer patients were in the rehabilitation phase (≥ 3 months post-completion of surgery, chemotherapy, and/or radiotherapy), receiving stable maintenance medications (e.g., endocrine therapy), which minimizes the potential confounding effect of other interventions on the cytokine and metabolomic profiles analyzed. The placebo granules, produced parallelly by the same manufacturer, were identical to the SNS granules in taste, smell, and color, ensuring blinding, and were packaged in identically designed bags.

The clinical validation cohort comprised a total of n = 20 patients from the previous trial. They were allocated equally to the SNS treatment group (n = 10) and the matching placebo group (n = 10). Blood samples were collected between 7-9 AM after a 12-hour overnight fast. Samples were processed within 30 minutes of collection: Centrifuged at 1500 × g for 10 minutes at 4 °C, aliquoted into cryovials, and stored at -80 °C.

T lymphocyte subsets

Peripheral blood samples of patients were collected and T lymphocyte subsets were detected by flow cytometry (FACS CANTO II, BD, San Jose, CA, United States). BD Multitest CD3/CD8/CD45/CD4 reagent (No. 340499, BD, San Jose, CA, United States) was used for the T lymphocyte percentage determinations. Laboratory tests were completed by the clinical laboratory department of Guangdong Provincial Hospital of Chinese Medicine.

Human cytokine array

Blood sample cytokines were examined using a QAH-CYT-1 antibody array (RayBiotech, United States), following the manufacturer’s guidelines. To measure cytokine secretion levels, 90 μL of concentrated conditioned medium was added to the array, incubated overnight at 4 °C, and then washed with a wash buffer. Biotinylated primary antibodies were added and incubated for 2 hours at room temperature, followed by additional washing. Subsequently, Cy3 equivalent dye-conjugated streptavidin was added and incubated for 1 hour at room temperature before scanning the array with an InnoScan 300 Microarray Scanner (Innopsys, France). An 8-point standard curve for each target protein was created using array-specific protein standards, and cytokine quantification was based on a standard curve generated from the same array. Partial least squares-discriminant analysis was conducted online through BioLadder (bioladder.cn).

Untargeted metabolomic

The analysis of blood sample metabolites was conducted using an Ultimate U3000 HPLC system (Thermo Fisher Scientific, MA, United States) coupled with a Q Exactive Plus mass spectrometer (Thermo Fisher Scientific, MA, United States). Pooled quality control samples were analyzed every 10 injections. Pearson correlation analysis of quality control results demonstrated that R-values approaching 1 indicate superior analytical process stability and higher data quality. Chromatography was carried out on an Acquity UPLC BEH C18 column (1.7 μm, 100 mm × 2.1 mm; Waters), with solvent A composed of ultrapure water and solvent B of acetonitrile (CAS 75-05-08; Merck, Germany). The gradient conditions included: 5% solvent B for 0-1 minute, a transition to 5%-100% solvent B over 19 minutes, a hold at 100% solvent B for 1 minute, and a final return to 5% solvent B for 4 minutes. The flow rate was set at 200 μL/minute, with a column temperature of 37 °C and an injection volume of 5 μL. Mass spectrometer settings were as follows: Spray voltage of 2.5 kV in negative ion mode and 3.0 kV in positive ion mode; sheath gas flow of 40; auxiliary gas flow of 10; and sweep cone gas flow of 0. The capillary temperature was maintained at 320 °C. Data acquisition and analysis were performed using Xcalibur 4.0 software (Thermo Fisher Scientific, MA, United States). Subsequent to raw data acquisition, Compound Discover 3.0 software (Thermo Fisher Scientific, MA, United States) was employed for processing. This involved normalizing the original metabolomics data across batches for comparison. Metabolite identification was based on m/z ratios (± 3 ppm error), retention times, and comparison with a mass spectrometry database. Principal coordinates analysis was conducted online through BioLadder (bioladder.cn). All metabolites reported in this study adhered to the standards set by the Metabolomics Standards Initiative.

RESULTS

Meta-analysis

Study selection and characteristics: The systematic search identified 2343 records from eight databases. After removing 218 duplicates, 2125 abstracts were screened against eligibility criteria (Figure 1). Full-text review of 35 articles yielded 20 qualifying RCTs (n = 1607 patients), including: 18 trials (n = 1409) comparing CHF with antidepressants, 2 trials (n = 198) evaluating CHF vs no intervention. All studies were conducted in China with treatment durations ranging from 4 weeks to 6 months. Outcome reporting included: 18 trials evaluating depression scales (HAMD/SDS), four trials evaluating QOL, five trials evaluating neurotransmitter levels (5-HT/DA/NE) and two trials evaluating immune markers (CD4+/CD8+ T cell subsets).

Figure 1 PRISMA flow diagram. RCT: Randomized controlled trial.

Methodological quality of included studies: The risk of bias for the included studies is depicted in Supplementary Figure 1. Eleven RCTs employed the random number method and were assessed as having a low risk of random sequence generation[31-41]. The remaining nine RCTs did not specify their randomization methods, resulting in unclear risk[42-50]. None of the studies explicitly mentioned allocation concealment or blinding, leading to high or unclear risk of bias in these domains. All 20 studies completely reported outcome data, with similar reasons for missing data, thus rated as low risk of attrition bias. The characteristics of included trials were shown in Table 1. The GRADE assessment indicated moderate-quality evidence for primary outcomes (HAMD, SDS, QOL), as detailed in Supplementary Table 3.

Table 1 Characteristics of included trials.

Ref.	Samples	Age (mean ± SD)		Intervention/experimental group	Control group	Intervention time/period	Outcomes
Liu and Xiao[44], 2011	60	E: 51.40 ± 8.7	C: 51.30 ± 6.6	Modified Xiaoyaosan (n = 30)	Flupentixol and melitracen tablets (n = 30)	6 weeks	(1)
Zhang[49], 2011	96	E: 35-70	C: 36-69	Modified Ganmaidazao decoction plus Xiaoyaosan (n = 48)	Alprazolam (n = 48)	6 weeks	(1)(2)(3)
Sun et al[46], 2015	58	E: 45.9 ± 11.7	C: 58.6 ± 35	Modified Xiaoyaosan (n = 29)	Flupentixol and melitracen tablets (n = 29)	6 weeks	(2)
Yan et al[47], 2015	68	38-69		Modified Xiaoyaosan (n = 34)	Paroxetine hydrochloride tablets (n = 34)	4 weeks	(1)
Zhang et al[48], 2015	60	E: 40-65	C: 35-67	Modified Xiaoyaosan (n = 30)	Fluoxetine hydrochloride tablets (n = 30)	3 weeks	(1)
Jin et al[43], 2016	82	E: 23-65	C: 24-67	Fuzhengjieyu decoction (n = 41)	Alprazolam (n = 41)	10 weeks	(1)(5)
Sun et al[36], 2016	64	24-73		Modified Xiaoyaosan (n = 32)	No intervention (n = 32)	6 weeks	(2)(4)
Chang et al[32], 2017	84	E: 39-70	C: 38-68	Shuganxiaobi decoction (n = 42)	Fluoxetine hydrochloride tablets (n = 42)	4 weeks	(1)
Shi et al[45], 2017	66	E: 35-68	C: 32-71	Modified Chaihuguizhi decoction (n = 36)	Paroxetine hydrochloride tablets (n = 30)	8 weeks	(1)
Hu et al[34], 2018	80	E: 47.37 ± 8.60	C: 48.23 ± 8.10	Jiawei Xiaoyao pill (n = 40)	Venlafaxine hydrochloride sustained-release tablets (n = 40)	1 month	(4)
Yang[50], 2018	92	E: 49.12 ± 7.96	C: 48.86 ± 8.13	Chaihulonggumuli decoction (n = 46)	Fluoxetine hydrochloride tablets (n = 46)	1 month	(1)
He[33], 2019	70	E: 51.83 ± 8.15	C: 50.77 ± 9.20	Danzhixiaoyao powder (n = 35)	Flupentixol and melitracen tablets (n = 35)	4 weeks	(1)
Huang et al[42], 2019	77	E: 46.26 ± 2.32	C: 45.72 ± 2.05	Modified Ganmaidazao decoction (n = 39)	Amitriptyline hydrochloride tablets (n = 38)	4 weeks	(1)(3)
Jiang[37], 2019	60	E: 42.08 ± 5.10	C: 41.93 ± 5.37	Chaihu plus Longgumuli decotion (n = 30)	Fluoxetine hydrochloride tablets (n = 30)	4 weeks	(1)
Wang et al[38], 2019	134	E: 42.3 ± 12.34	C: 40.57 ± 13.91	Xiaoyao powder (n = 67)	No intervention (n = 67)	6 months	(1)(3)(5)
Lin[35], 2022	70	E: 47.33 ± 5.96	C: 46.82 ± 6.14	Jieyusanjie decoction (n = 35)	Sertraline hydrochloride tablets (n = 35)	4 weeks	(1)
Xiao[39], 2021	100	E: 45.81 ± 11.56	C: 46.37 ± 12.21	Modified Xiaoyao powder (n = 50)	Paroxetine Hydrochloride tablets (n = 50)	3 months	(1)(4)
An et al[31], 2022	120	E: 55.76 4 ± 8.81	C: 56.05 ± 8. 73	Chaihu plus Longgumuli decoction (n = 60)	Escitalopram tablets (n = 60)	60 days	(1)(4)
Zhang[40], 2022	60	E: 54.67 ± 6.87	C: 54.20 ± 7.56	Chaihushugan powder (n = 30)	Flupentixol and melitracen tablets (n = 30)	4 weeks	(2)(3)
Zhong et al[41], 2023	106	E: 52.09 ± 9.07	C: 51.23 ± 8.91	Modified Fangjidihuang (n = 53)	Sertraline hydrochloride tablets (n = 53)	8 weeks	(1)(4)

(1) Hamilton Depression Scale; (2) Self-rating Depression Scale; (3) Quality of Life; (4) 5-hydroxytryptamine, dopamine, and norepinephrine; (5) CD4, CD8, CD4/8. For experimental group, a dose of 150-300 mL of the traditional Chinese medicine decoction was given twice daily in the morning and evening; for control group, antidepressants are taken according to the corresponding instructions.

Therapeutic efficacy of CHF on relieving depression in breast cancer patients: A total of 18 RCTs involving 1461 patients reported depression outcomes. The meta-analysis of direct comparisons included 16 RCTs (n = 1263) that compared CHF with antidepressants, using either HAMD or SDS. Two additional RCTs (n = 198) comparing CHF with no intervention were described narratively due to differences in measurement tools. For the comparison between CHF and antidepressants assessed by HAMD, 15 studies involving 1205 breast cancer patients were included (Figure 2A). CHF therapies significantly reduced HAMD scores compared to selective serotonin reuptake inhibitors (MD = -4.32, 95%CI: -5.59 to -3.05, P < 0.00001). Besides, CHF also showed superiority over flupentixol and melitracen in improving depression scores (MD = -5.62, 95%CI: -8.19 to -3.06, P < 0.0001). CHF presented a significant advantage in reducing depression score compared with antidepressants (MD = -5.33, 95%CI: -6.93 to -3.73, P < 0.00001). For the comparison between CHF and antidepressants assessed by SDS, three studies involving 214 breast cancer patients were included (Figure 2B). CHF significantly reduced depression scores compared to antidepressants (MD = -10.09, 95%CI: -16.48 to 3.71, P = 0.002). In addition, compared to no intervention, Sun et al[36] reported CHF reduced SDS scores (MD = -15.43, 95%CI: -21.33 to -9.52), while Wang et al[38] reported CHF reduced HAMD scores (MD = -9.41, 95%CI: -14.14 to -4.68).

Figure 2 Therapeutic effectiveness of Chinese herbal formula on relieving depression in breast cancer patients. A: Forest plot of Hamilton Depression Rating Scale; B: Forest plot of Self-rating Depression Scale. HAMD: Hamilton Depression Rating Scale; CHF: Chinese herbal formula; CI: Confidence interval; SDS: Self-rating Depression Scale.

The influence of CHF on improving QOL in breast cancer patients: Four RCTs involving 367 patients reported on QOL as assessed by the Karnofsky Performance Scale and were included in the meta-analysis (Supplementary Figure 2). Results from three studies involving 233 breast cancer patients showed that CHF treatment significantly improved QOL compared to antidepressants (MD = 9.13, 95%CI: 6.69-11.57, P < 0.00001). One study also reported that CHF was significantly better than no intervention.

The influence of CHF treatment duration on depression and frequency statistics of herbal medicine: In order to evaluate the influence of treatment duration on the therapeutic efficacy of CHF, a subgroup analysis was performed according to different intervention duration (≤ 4 weeks or > 4 weeks). As shown in Supplementary Figure 3, CHF treatment could lead to improvements in depression either for using shorter or longer than four weeks when compared to antidepressants. Notably, patients with treatment duration exceeding four weeks seemed to obtain more advantage in relieving depression (MD = -4.99, 95%CI: -6.34 to -3.64, P < 0.00001) compared to the antidepressant group. These findings revealed that the intervention duration may be a crucial factor influencing the therapeutic efficacy of CHF.

Safety outcomes: In this study, ten RCTs reported that the incidence of adverse events (AEs). AEs were actively collected through structured interviews at each study visit and/or patient diaries in the original trials. The reported AEs included dry mouth, constipation, dizziness and headache, poor appetite and indisgestion, insomnia, abdominal pain, somnolence, lack of strength, nausea and vomiting, liver and kidney dysfunction, alopecia, blurred vision, as well as fever. The incidence of these AEs may be attributed to breast cancer patients undergoing concurrent radiotherapy, chemotherapy, and endocrine therapy often experience varying degrees of breast cancer treatment-related adverse effects. As shown in Supplementary Figure 4, the CHF treatment group was associated with a significantly lower incidence of adverse reactions compared to the control group (risk ratio = 0.36, 95%CI: 0.25-0.51, P < 0.00001).

The influence of CHF on 5-HT, DA, and NE in breast cancer patients: Data on 5-HT and NE levels were reported in five RCTs (n = 470), while DA levels (pre- and post-treatment) were reported in four RCTs (n = 350); all were included in the meta-analysis. Compared to antidepressants, CHF significantly increased 5-HT (MD = 33.98, 95%CI: 14.59-53.37, P = 0.0006), DA (MD = 27.45, 95%CI: 23.03-31.88, P < 0.00001), and NE (MD = 17.99, 95%CI: 8.15-27.82, P = 0.0003) (Figure 3). One study also favored CHF over no intervention in regulating 5-HT, DA, and NE[34].

Figure 3 The influence of Chinese herbal formula on 5-hydroxytryptamine, dopamine, and norepinephrine in breast cancer patients. A: Forest plot of 5-hydroxytryptamine; B: Forest plot of dopamine; C: Forest plot of norepinephrine. CHF: Chinese herbal formula; CI: Confidence interval; 5-HT: 5-hydroxytryptamine; DA: Dopamine; NE: Norepinephrine.

The influence of CHF on CD4+ and CD8+ T lymphocytes in breast cancer patients: Two RCTs involving 216 cases reported the changes of CD4+ and CD8+ T lymphocytes, one vs antidepressants while another vs no intervention, respectively. All were included in the meta-analysis. It was found that CHF treatment greatly improved CD4+ T population either comparing with antidepressants or placebo group (MD = 7.74, 95%CI: 4.75-10.72, P < 0.00001). However, little statistical difference was found in the clinical efficacy of CHF elevating CD8+ T population (MD = -0.15, 95%CI: -1.18 to 0.89, P = 0.78) (Figure 4).

Figure 4 The influence of Chinese herbal formula on CD4+ and CD8+ in breast cancer patients. A: Forest plot of CD4+; B: Forest plot of CD8+. CHF: Chinese herbal formula; CI: Confidence interval.

Publication bias and sensitivity analysis: Evaluation of publication bias through funnel plot analysis revealed no complete symmetry and indicated the existence of publication bias (Supplementary Figure 5). The publication bias may be associated with negative results not being published. To assess result stability, we performed sensitivity testing by systematically removing each study and recalculating effect sizes, which demonstrated consistent treatment effects across all iterations, supporting the reliability of our primary conclusions.

Network pharmacology analysis for SNS in the anti-depression treatment of breast cancer

The meta-analysis indicated that the majority of the formulations included were derived from the classical antidepressant formula SNS. Preclinical evidence supports the potential of SNS in suppressing breast cancer growth and metastasis induced by chronic psychological stress (Figure 5A). Specifically, SNS disrupts the 78kDa glucose regulated protein-lipoprotein receptor-related protein 5 interaction on the cell membrane, thereby inhibiting Wnt/β-catenin signaling in breast cancer stem cells[25]. Furthermore, naringenin, a bioactive compound present in SNS, has demonstrated the ability to impede breast cancer progression through modulation of the farnesoid X receptor/hepatocyte nuclear factor 4α/estrogen sulfotransferase pathway[26]. SNS also downregulates the glycolysis-related proteins that are upregulated by chronic psychological stress[51]. Nevertheless, a thorough understanding of the pharmacological mechanisms underlying the use of SNS for the treatment of depression in patients with breast cancer necessitates additional research.

Figure 5 Network pharmacology analysis for Si-Ni-San in the anti-depression treatment of breast cancer. A: Preclinical evidence of Si-Ni-San in suppressing breast tumor growth and metastasis induced by chronic psychological stress; B: The intersection of target genes involved in top five herbs, breast cancer and depression; C: Protein-protein-interaction network analysis of the common target genes; D: Biological process enrichment analysis of the common target genes; E: Molecular function enrichment analysis of the common target genes; F: Cellular component enrichment analysis of the common target genes; G: Kyoto Encyclopedia of Genes and Genomes enrichment analysis of the common target genes. CSCs: Cancer stem cells.

Using network pharmacology, we identified 57 active ingredients within SNS. Meanwhile, 193 unique potential targets of these components were retained after removing duplicates. Furthermore, we obtained 9151 targets related to breast cancer and 9121 targets associated with depression from GeneCards. Intersection of these target sets yielded 153 common genes (Figure 5B). Protein-protein interaction analysis further highlighted a total of 93 significant genes, including interleukin-10 (IL10), IL1A, CXC motif chemokine ligand 11 (CXCL11), CXCL10, IL6, CXCL2, CXCL8, etc. (Figure 5C). Gene Ontology enrichment analysis indicated that these genes are primarily involved in immune-related biological processes such as positive regulation of transcription driven by immune response and tumor necrosis factor production (Figure 5D). Within the cellular component category, extracellular exosome was the most significantly enriched term (Figure 5E). For molecular function, ATP binding was the most prominent (Figure 5F). KEGG pathway analysis revealed significant enrichment in pathways including choline metabolism in cancer and the serotonergic synapse pathway (Figure 5G), both of which are implicated in cancer progression and depression.

Experimental validation of the antidepressant mechanism of SNS

Despite the encouraging preclinical data that suggest the effectiveness of SNS in ameliorating depressive symptoms and enhancing the prognosis of breast cancer, there is a paucity of well-controlled clinical trials among breast cancer patients with depression. To validate our findings in meta-analysis and network pharmacology, we utilized clinical specimens derived from a trial intended to assess the effectiveness of SNS in treating breast cancer patients experiencing depression. The experimental flow chart was summarized in Figure 6A. Notably, SNS administration significantly increased CD4+ T cell levels in two independent comparisons (P < 0.05; Figure 6B). Meanwhile, partial least squares-discriminant analysis of cytokine profiles revealed clear separation between the SNS and placebo groups (Figure 6C), indicating that SNS markedly altered the cytokine landscape between groups. In particular, the key cytokines derived from CD4+ T cells, including IL-4, IL-5, IL-10, and IL-13, were significantly downregulated following SNS treatment (Figure 6D), further underscoring the pivotal role of CD4+ T cells in SNS-mediated antidepressant effects.

Figure 6 Experimental validation of the antidepressant mechanism of Si-Ni-San. A: Experimental design schematic comparing the Si-Ni-San treatment group to the placebo control group; B: Alterations in the frequencies of CD4+ and CD8+ T cell populations between groups (n = 10); C: Partial least squares-discriminant analysis of serum cytokine profiles between groups (n = 10 per group); D: Expression levels of key cytokines derived from CD4+ T cells between groups; E: Principal coordinates analysis of serum metabolomic profiles between groups (n = 10 per group); F: Heatmap of serum metabolomic between groups; G: Differential abundance of metabolites between groups; H: Summary of antidepressant mechanisms of Si-Ni-San. SNS: Si-Ni-San; PLS-DA: Partial least squares-discriminant analysis; IL: Interleukin; PCoA: Principal coordinates analysis; CSCs: Cancer stem cells; 5-HTTP: 5-hydroxy-DL-tryptophan; 5-HIAA: 5-hydroxyindoleacetic acid; IAM: Indole-3-acetaldoxime. ^aP < 0.05, ^bP < 0.01.

Metabolomic profiling via principal coordinates analysis also showed distinct clustering between groups (Figure 6E), demonstrating substantial shifts in the metabolome. Upon the application of a stringent threshold (|fold change| > 5), we identified 49 metabolites exhibiting differential expression (Figure 6F). Among these, the levels of L-tryptophan, 5-hydroxy-DL-tryptophan, and 5-hydroxyindoleacetic acid were increased significantly following SNS treatment (P < 0.05). Meanwhile, the levels of metabolites such as indole-3-acetaldoxime, aceclidine, alprenolol, phenmetrazine, 2,2,2-trichloroethanol and desmethyltamoxifen were markedly inhibited after SNS treatment (P < 0.05; Figure 6G). Therefore, integrating these metabolic alterations with the established pathophysiology of depression and previous findings[24-26] (Figure 6H), we propose that SNS alleviates depression through a multi-system mechanism encompassing immunomodulation, systemic neuromodulation, metabolic reprogramming, and pathways related to cancer stem cells and glycolysis.

DISCUSSION

Main findings

In this study, we revealed that CHF intervention showed great efficacy in relieving depression, and demonstrated a stronger alleviating effect on symptoms when compared with antidepressants. Additionally, CHF therapies significantly enhance QOL and increase serum levels of 5-HT, DA and NE, while improving the immune index of CD4+ T lymphocytes. It is noteworthy that the classical formula SNS has emerged as a foundational element supporting these therapeutic effects. Further experimental analyses indicated that SNS may exert its antidepressant actions primarily through modulating CD4+ T cell function and multi-organ regulation (Figure 7).

Figure 7 Chinese herbal formulas alleviated depression in breast cancer patients. RCTs: Randomized controlled trials; MD: Mean difference; IL: Interleukin; 5-HTP: 5-hydroxytryptophan; IAM: Indole-3-acetaldoxime; IAA: Indole-3-acetic acid; 5-HIAA: 5-hydroxyindoleacetic acid; CSCs: Cancer stem cells; GRP78: 78 kDa glucose regulated protein; LRP5: Lipoprotein receptor-related protein 5; LDHA: Lactate dehydrogenase A; PDK1: Pyruvate dehydrogenase kinase 1; PDHA: Pyruvate dehydrogenase alpha 1.

Interpretation of findings

Unlike previous meta-analysis of CHF applied in mental disorders[52-54] or mixed cancers[55,56], our study focused on breast cancer patients with depression. Compared with depression in general population, breast cancer related depression is persistent, more disseminated and poorly controlled[57]. Meanwhile, the impact of antidepressants on breast cancer progression is also a serious concern. Long-term use of antipsychotic medications has been linked to an increased risk of breast cancer[58]. Notably, CYP2D6 inhibitors like paroxetine, when co-administered with tamoxifen, have been reported to increase breast cancer-related mortality[59]. These factors significantly affect breast cancer patients’ compliance with antidepressants due to potential drug interactions with chemotherapeutic agents or biological therapies. In contrast, CHF, which have been used for millennia to treat mental disorders, are characterized by multiple targets, low toxicity, and systematic efficacy. Consistent with previous reports[60-62], we also validated that CHF can significantly improve depressive symptoms of breast cancer patients as an adjunctive therapy. Notably, our results showed that the formulas present better efficacy than antidepressants when the administration duration was longer than four weeks. Considering the mild pharmacological activity of CHF, we speculate that CHF may require a longer duration to reach consistent efficacy. As expected, our results showed that the formulas present better efficacy than antidepressants when the administration duration was longer than four weeks. This temporal pattern likely reflects CHF’s gradual system-regulating effects rather than immediate pharmacological action. In addition, the significantly reduced AE incidence further supports CHF’s clinical utility, as recognized by leading institutions like MD Anderson Cancer Center through their incorporation of Chinese medicine into integrative oncology programs[63]. These collective findings position CHF as a valuable complementary approach for managing depression in breast cancer patients, though additional controlled trials are needed to establish optimal treatment protocols and duration. Research should particularly focus on standardizing formulations and evaluating long-term outcomes to facilitate clinical implementation. In addition, CHF has demonstrated distinctive therapeutic advantages in managing numerous complex conditions, such as rheumatoid arthritis, irritable bowel syndrome, and mammary hyperplasia[64-67]. These clinical benefits are fundamentally attributable to their multi-target, multi-component, and multi-level regulatory mechanisms, which enable a holistic modulation of disease networks. For example, beyond its efficacy in breast cancer-related depression, SNS has been shown to alleviate a spectrum of disorders including adolescent depression, liver injury, acute colitis, and anxious insomnia[68-71]. Our study also revealed that the pharmacological activities of SNS were closely correlated with the modulation of immune system, tryptophan metabolism, bile acid metabolism, neurotransmitters, glucose metabolism, as well as cancer stem cell signaling activation[26,51,72]. Collectively, these phenomena underscore the core TCM principle of “treating different diseases with the same strategy”, wherein a single formula exerts therapeutic effects across multiple diseases through its system-regulating action.

The pathophysiology of depression is complex and involves multiple pathways, including the hypothalamic-pituitary-adrenal axis, the gut-brain-microbiome axis, brain-derived neurotrophic factor, monoamine neurotransmitters, and cytokines[73]. The monoamine hypothesis of depression posits that the dysregulation of 5-HT, NE and DA contributes to depression occurrence and establishes the cornerstone of current pharmacological treatments for depression[74]. In the present study, we observed that CHF interventions were more effective than antidepressants in increasing levels of 5-HT, DA, and NE. KEGG pathway analysis highlighted the neuroactive ligand-receptor interaction pathway as significantly enriched, suggesting that CHF may modulate the key neurotransmitter system to improve the prognosis of depression. This is consistent with previous meta-analyses that have reported an elevation of 5-HT, DA, and NE levels following treatment with CHF[75]. With advancements in multidisciplinary techniques, the antidepressant mechanisms of CHF have been increasingly elucidated.

To elucidate the specific mechanisms underlying this modulation, we conducted an untargeted metabolomic analysis of the foundational formula SNS. The findings uncovered a synchronized reorganization of metabolic processes, characterized by a deliberate improvement of the serotonergic pathway, as indicated by marked increases in L-tryptophan, 5-hydroxy-DL-tryptophan, and 5-hydroxyindoleacetic acid, coupled with a reduction in Indole-3-acetaldoxime. This signature suggests a shift in tryptophan metabolism away from competing catabolic routes and toward serotonin synthesis, a process potentially facilitated via the gut-brain axis[76,77]. Concurrently, we observed a marked decline in various neuroactive substances, including phenmetrazine, alprenolol, desmethyltamoxifen, aceclidine and 2,2,2-trichloroethanol. This coordinated decrease signals a reduction in the overall neuroactive load, reflecting a systemic neuromodulatory reset induced by SNS treatment. Integrating these metabolic findings with the established pathophysiology of depression and prior findings[24-26], we propose that SNS exerts its antidepressant effect via a multi-system mechanism. This mechanism entails immunomodulation, a reduction in neuroactive burden, a reprogramming of tryptophan metabolism, and the modulation of cancer-associated pathways, including cancer stem cells and glycolysis. Consequently, SNS and similar CHF represent a promising class of multi-target therapeutics, whose efficacy warrants further validation in rigorously controlled clinical trials.

Immune suppression microenvironment plays a crucial role in cancer development, particularly given the pivotal role of T lymphocytes in the anti-cancer battle[78]. The interplay between immune indices and depression has also emerged as a significant topic in oncology research[79]. In this study, CHF treatment was significantly more effective in increasing CD4+ T lymphocytes compared to antidepressant intervention. This finding aligns with studies reporting a negative correlation between CD4+ T levels and depression, suggesting that an increased CD4+ population may ameliorate depressive symptoms[80]. Single-cell RNA sequencing analysis demonstrated a reduced presence of naive T cells, especially CD4+ naive T cells, in depression patients relative to controls, and highlighted the ETS-mitogen-activated protein kinase pathway in T cell activation during antidepressant treatment in major depressive disorder[81]. Meanwhile, higher levels of CD3+, CD4+, and CD8+ T cells have been associated with improved survival rates among breast cancer patients[82]. In present study, CD4+ T cell and its key cytokines including IL-4, IL-5, IL-10, IL-13 were significantly modulated following SNS treatment. The observed increase in CD4+ T cell may reflect the activation of beneficial immune responses induced by SNS treatment. Simultaneously, the reduction in type 1 helper T (Th2)-associated cytokines, including IL-4, IL-5, and IL-13[83], likely indicates a favaroble shift, suggesting that SNS attenuates Th2-polarized immunity, which is typically deemed detrimental to anti-cancer defense mechanisms. As a key immunosuppressive cytokine predominantly produced by regulatory T cells, the decline in IL-10 likely reflects a reduction in regulatory T cell activity or abundance. Those points to a shift away from an immunosuppressive state towards a more immunopermissive microenvironment, which may not only restore anti-tumor immune competence but also contribute to the alleviation of inflammation-associated depressive symptoms. This immunomodulatory pattern is consistent with previously reported effects of various bioactive components in Chinese Medicine, including Ganoderma lucidum polysaccharide and Ginseng polysaccharides, which have been shown to inhibit Th2 cytokines and promote Th1 responses[84,85]. Collectively, these findings collectively underscore the unique advantage of immunomodulation effect offered by CHF.

QOL is a vital consideration for cancer survivors, as the five-year survival ratio has been greatly prolonged with the development of multidisciplinary strategies. For breast cancer, the poor QOL exited in most patients, with domains including physical, emotional and social domains[86]. Notably, QOL was also closely associated with mortality risk in breast cancer patients[87]. Our analysis confirms CHF’s positive impact across multiple QOL parameters, consistent with previous reports of improved functioning and symptom control[60,61]. American Cancer Society also suggest acupuncture and Qigong should be considered for improving QOL in cancer patients[29]. According to a dual-center trial in America, acupuncture improved QOL for patients with breast cancer over time[88]. Regarding CHF, breast cancer patients receiving formulas during cancer treatment reported higher QOL scores, compared to those without formula interventions[89]. Additionally, a significant improvement in QOL has been demonstrated for breast cancer patients receiving the CHF PRM1201 during chemotherapy, with multiple indexes including overall life quality, physical capacity, role performance, emotional well-being, and mitigating fatigue and appetite loss showing improvement after PRM1201 administration[90]. However, the beneficial effects of CHF are still needed to be validated by large-scale multi-center RCTs. These positive findings encourage the potential practice of CHF in enhancing QOL of breast cancer patients.

Implications and limitations

This study demonstrates the superior efficacy and safety of CHF for breast cancer-related depression, evidenced by improving depressive symptoms, QOL, monoamine neurotransmitter levels and immune function. Several limitations should be considered. First, the majority of included RCTs were conducted in China, and language restrictions may introduce selection bias and limit the sample size and generalizability of the findings. Second, the impact of CHF on varying severity levels of depression could not be assessed due to insufficient reporting in the original studies. Third, the potential benefits of CHF on long-term oncological outcomes such as overall survival or recurrence rate, remain unclear, as included trials had short follow-up periods. Furthermore, while mechanistic insights from SNS provide valuable clues for understanding the anti-depression mechanism of CHF, these findings require further experimental validation. To address these gaps, future research should prioritize large-scale, multi-regional RCTs that adhere to standardized protocols and reporting guidelines, such as the CONSORT statement. Emphasis should be placed on rigorous randomization, blinding, and allocation concealment. Additionally, the utilization of standardized assessment instruments to gauge the severity of depression and the integration of sustained longitudinal follow-up are imperative for confirming the enduring efficacy of CHF and its impact on survival metrics. Such efforts would enhance the reproducibility, translational value, and global applicability of CHF in treating breast cancer-related depression.

CONCLUSION

In conclusion, this study suggests that CHF, particularly SNS, is associated with greater improvement in depression outcomes compared to conventional antidepressants among breast cancer patients. This is supported by observed positive effects on monoamine neurotransmitter levels and CD4+ T lymphocyte counts. However, these conclusions must be interpreted with caution given the methodological limitations of the included trials, such as inadequate blinding and allocation concealment, as well as the observed funnel plot asymmetry. While the findings support the potential integration of CHF into management strategies for breast cancer-related depression, further rigorous, large-scale RCTs with robust blinding and longer follow-up are needed to confirm these benefits, elucidate the mechanisms, and assess the long-term impact on both depression and oncological outcomes.