Abstract
Background:
Breast cancer is the most common cancer and the main cause of death because of malignant tumors in women, worldwide. The impact of Crocus sativus on several cancers has been discussed. Recent studies provide evidence regarding the anticancer properties of C. sativus and its bioactive constituents against breast cancer. This study aims to systematically review the efficacy of this botanical drug and its constituents on breast cancer, and their mechanism of action for the first time. Due to the lack of human studies in this field, the present research focused on preclinical studies.
Methods:
In this systematic review, scientific databases, including PubMed, Web of Sciences, Google Scholar, Scopus, and Scientific Information Database were explored profoundly. Preclinical studies published until the end of 2024 that had investigated the therapeutic properties of C. sativus, or its bioactive constituents including crocin, crocetin, safranal, or picrocrocin against breast cancer were selected.
Results:
Forty-four studies examining the effect of C. sativus or its bioactive constituents against breast cancer were obtained. Preclinical in vitro and in vivo studies have demonstrated the potential and targeted anticancer properties of the metabolites found in saffron (C. sativus). These metabolites, such as crocin, crocetin, and safranal, exhibit their anticancer effects through various mechanisms, including induction of apoptosis, modulation of the cell cycle, and other pathways.
Conclusions:
C. sativus and its constituents exerts their anticancer activity with different mechanisms. A considerable number of the included studies highlight induction of apoptosis and modulation of the cell cycle. The findings of our study suggest that certain compounds, particularly crocin and crocetin, have significant anticancer properties. In particular, crocin provided the highest level of evidence of efficacy in preclinical research, indicating its potential for further investigation.
Introduction
Breast cancer is known as the most common cancer and the main cause of death because of malignant tumors in females.1,2 Several factors such as genetics, and lifestyle affect the risk of breast cancer and would influence the rate of mortality. 3 The nature of this disease is very heterogeneous with variations in proliferative index, immunohistochemistry, clinical presentation, and histological grade. 4 The medicinal plan in patients suffering from breast cancer often depends on the cancer subtypes including Her 2 amplified, and hormone receptor-positive subtypes. 5 The main therapeutic options for breast cancer patients at early stages are chemotherapy, radiotherapy, surgical resection, and hormone therapy. 6 Surgery is now being recommended more frequently, particularly in cases where metastasis has occurred.6,7 The prognosis of breast cancer is also influenced by the stage of the disease, which is determined by factors such as the primary tumor size, involvement of axillary lymph nodes, and the presence of distant metastasis.6,8 The variability in presentation and response to treatment has led to a comprehensive and collaborative approach that incorporates the use of natural remedies to improve survival rates. These multifaceted approaches rely heavily on early diagnosis of the disease. 9 Worldwide, individuals with persistent chronic conditions such as cancer and acquired immunodeficiency syndrome utilize complementary and alternative medicine including botanical drugs to enhance their quality of life and alleviate the psychosocial and medical challenges they face.10,11
Natural remedies have shown promising potential as agents that combat tumors and cancer. They have also exhibit reduced toxicity compared to conventional hormonal targeting anti-cancer agents, which often encounter recurrent resistance (known as multi-drug resistance).12,13 These benefits are attributed to the antioxidant and anti-inflammatory properties of botanical drugs, and their ability to modulate the immune system and induce anti-proliferative and apoptotic effects on neoplastic cells.14 -16 This approach aims to provide a chemo-preventive quality that can serve both as a preventive measure and as a therapeutic option while ensuring long-term safety.17,18 Several studies have presented evidence supporting the effectiveness of natural products, such as botanical drugs, in the development of anticancer medications and in mitigating the adverse effects induced by chemotherapy.18 -21 Although most of the studies conducted so far on the effects of numerous botanical drugs such as Curcuma longa, Nigella sativa, Matricaria chamomilla, and also their constituents on various cancers, including breast cancer, are preclinical,22 -26 some of the common drugs used in the treatment of breast cancer are extracted from medicinal plants. 27 The therapeutic potential and tolerability of various bioactive compounds derived from herbs or their semi-synthetic derivatives have been attempted in breast cancer treatment. Vinca rosea (vinblastine, vinorelbine), Taxus baccata (paclitaxel, docetaxel), Camptotheca acuminata (camptothecin), and Podophyllum peltatum (etoposide) are chemotherapeutic drugs originated from herbal medicine; their efficacy against breast cancer has been assessed in clinical trials.27 -29
Crocus sativus is a botanical drug that belongs to the iris family (Iridaceae) and primarily grows in Iran, and certain regions of China, like Tibet, and India. The flower of C. sativus contains various chemical components that have therapeutic potential, leading to its extensive use as a traditional medicine over a significant period. 30 C. sativus is a well-known spice traditionally used for food coloring and flavoring. It comprises several metabolites, including crocin, crocetin, picocrocin, and safranal, each possessing distinct pharmacological effects. Crocin, a carotenoid compound, crocetin, a dicarboxylic acid, and safranal, an aldehyde compound, are the metabolites found in C. sativus. 31 Apocarotenoids, such as crocetin (C20H24O4) and crocin (digentiobiosyl8, 80-diapocarotene-8, 80-oate; C44H64O24), are the metabolites responsible for the red color of C. sativus stigmas. Additionally, picrocrocin (4-[β-D glucopyranosyloxy] -2, 6, 6- trimethylcyclohex-1-ene- 1-carboxaldehyde; C16H26O7) gives C. sativus its bitter taste, while safranal (C10H14O7) contributes to its strong aroma. 32
Regarding medicinal properties, C. sativus exhibits sedative, antispasmodic, hepatoprotective, and immune system booster activities.33 -35 Numerous studies have previously explored the potential anticancer effects of C. sativus in various cancer types, including gastrointestinal and gynecologic cancers.36,37 Although considerable investigations have evaluated the effectiveness of C. sativus or its bioactive constituents in various diseases, such as depression, anxiety, dysmenorrhea, etc.,38 -40 unfortunately, no clinical trial has examined the effectiveness of this herb in the treatment of any cancer. Based on preclinical research, C. sativus has demonstrated several antitumor mechanisms such as the induction of apoptosis, inhibition of angiogenesis, anti-inflammatory effects that lead to the reduction of inflammation in the tumor microenvironment, and thus the rate of tumor progression, and antioxidant activity to help neutralize free radicals and oxidative stress.41,42 The objective of this review is to systematically gather and summarize literature regarding the effectiveness of C. sativus and its metabolites in the management of breast cancer.
Study Design
This systematic review has evaluated the efficacy of C. sativus and its constituents in breast cancer. The authors initially considered human studies for inclusion in the review; however, no eligible clinical trials were identified in the literature search. Thus, this review focused mostly on preclinical research (in vivo and in vitro).
The Strategy of Literature Review
To gather studies evaluating the impact of C. sativus and its constituents on breast cancer, a comprehensive search was conducted in scientific databases including PubMed, Web of Sciences, Google Scholar, Scopus, and Scientific Information Database. The search encompassed articles published from the inception of these databases up until the end of 2024. A combination of Medical Subject Headings (MeSH) and non-MeSH keywords was employed to ensure a thorough exploration of the databases. The names of the breast cancer cell lines commonly used in breast cancer research were also obtained from a review article. 43 Subsequently, a search strategy was designed as (Crocus sativus OR its main constituents) AND (breast OR different breast cancer cell lines). Supplemental File 1 presents the full search strategy and terms used.
Furthermore, a comprehensive examination of the references cited in the initially selected papers was performed to identify any potentially overlooked relevant studies.
Study Selection
All studies including in vivo, in vitro, and in clinical settings were considered. Unpublished reports, gray literature, editorial letters, review articles, books, and articles that were not available in English or Persian were excluded.
The PICOS criteria (Population, Intervention, Comparison, Outcome, Study design) was considered to select the eligible studies.
Population
For human studies, all breast cancer cases regardless of the cancer type were eligible for inclusion. For animal studies, all breast cancer models, regardless of how cancer was induced can be included. For in vitro researches, applying any of breast cancer cell lines including BT483, CAMA1, EFM19, HCC1428, HCC712, IBEP2, KPL1, LY2, MCF7, MDAMB134, MDAMB134VI, MDAMB175, MDAMB175VII, MDAMB415, T47D, ZR751, ZR75B, BSMZ, BT474, EFM192A, IBEP1, IBEP3, MDAMB330, MDAMB361, UACC812, ZR7527, ZR7530, 21MT1, 21MT2, 21NT, 21PT, AU565, HCC1008, HCC1569, HCC202, HCC2218, HH315, HH375, HCC1954, KPL-4, MDAMB453, OCUB-F, SKBR3, SKBR5, SUM190PT, SUM225CWN, UACC893, BT20, CAL148, DU4475, EMG3, HCC1143, HCC1187, HCC1599, HCC1806, HCC1937, HCC2157, HCC3153, HCC70, HMT3522, KPL-3C, MA11, MDAMB435, MDAMB436, MDAMB468, MFM223, SUM185PE, SUM229PE, BT549, CAL120, CAL51, CAL851, HCC1395, HCC1739, HCC38, HDQ-P1, Hs578T, MDAMB157, MDAMB231, SKBR7, SUM102P, SUM1315M02, SUM149PT, SUM159PT was acceptable for inclusion.
Intervention
Studies that had investigated the therapeutic properties of C. sativus, or its bioactive constituents including crocin, crocetin, safranal, or picrocrocin, regardless of the dosage and the method of administration were selected.
Comparison
Studies with any type of comparison group were considered eligible for inclusion.
Outcome
Researches that evaluated different outcomes related to breast cancer, such as tumor size, apoptosis rates, overall survival, and tumor-associated biomarkers were eligible for inclusion in the current review.
Study Design
Any in vivo and in vitro studies may be included in this review.
Review articles, gray literature, books, editorial letters, unpublished reports, and articles that were not available in full text in English or Persian were excluded from consideration.
Two reviewers independently assessed the suitability of primary studies based on their titles and abstracts (FSH, and MA). In cases of disagreement between the 2 reviewers, a third reviewer was consulted to reach a consensus.
Data Extraction
The authors adhered to established protocols for gathering and examining the data. They obtained and assessed information from chosen articles concerning the substances, animal models, cell lines, histological assessments, biochemical assays, and molecular mechanisms investigated in the studies.
Quality Assessment of the Studies
The bias risk of in vivo studies was determined using SYRCLE’s risk of bias tool for animal studies. 44 Several biased aspects of animal studies such as selection, performance, detection, attrition, and reporting biases were evaluated.
Data Analysis
Due to differences in the methodologies used in the studies, the meta-analyses were not applicable.
Studies Description
In this research, various studies were evaluated to investigate the effects of C. sativus and its main constituents on breast cancer. A total of 217 search results were initially obtained regarding the impact of C. sativus or its metabolites on the different breast cancer subtypes or breast cancer cell lines. After excluding 173 articles that were reviews, books, duplicate articles, indexes, and other irrelevant sources, 44 were selected for the current review (Figure 1). This systematic electronic search was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. 45

Steps to select suitable articles based on the inclusion and exclusion criteria defined for this review.
Effects of C. sativus and Its Constituents Against Breast Cancer and the Proposed Mechanisms
The efficacy of C. sativus and its constituents against breast cancer has been demonstrated in several preclinical in vivo and in vitro researches. C. sativus extract and its metabolites including crocetin, crocin, and safranal have shown significant anticancer properties in animal breast cancer models and various breast cancer cell lines. Table 1 presents the beneficial effects of C. sativus and its metabolites in breast cancer, as well as some of the established mechanisms. Table 2 indicates the therapeutic properties of C. sativus and its metabolites in combination with chemotherapy agents or other therapeutic methods against breast cancer.
Therapeutic Effects of Crocus sativus and Its Constituents Against Breast Cancer.
Abbreviations: PRKCQ, protein tyrosine kinase C theta isoform; DNA, deoxyribonucleic Acid; NF-Κb, nuclear factor kappa-light-chain-enhancer; FOXP2, forkhead box protein P2; SPRY2, sprouty RTK signaling antagonist 2; XBP1, X-box binding protein 1; VEGF, vascular endothelial growth factor; VEGFR, vascular endothelial growth factor receptor; PTEN, phosphatase and tensin homolog; Akt1, AKT Serine/Threonine Kinase 1; Bcl-2m, B-cell lymphoma protein 2; ROS, reactive oxygen species; FOXO, forkhead box transcription factor class O; MMPs, matrix metalloproteinases; EDU, 5-ethnyl-2′-deoxyuridine; CCK-8, cell counting kit-8; TUNEL, terminal deoxynucleotidyl transferase dUTP nick end labeling.
Therapeutic Effects of Crocus sativus and Its Constituents in Combination With Other Therapeutic Methods Against Breast Cancer.
Abbreviations: PTEN, phosphatase and tensin homolog; VEGF, vascular endothelial growth factor; Bcl-2m, B-cell lymphoma protein 2; ATG1, autophagy-related 1; Hsp, heat shock protein; LDH, lactate dehydrogenase; MMP, matrix metalloproteinase; VEGFR2, vascular endothelial growth factor receptor; mRNA, messenger ribonucleic acid; SIRT-1, silent information regulator sirtuin 1; hTERT, human telomerase reverse transcriptase; HA-Cd-NC, hyaluronic acid- cadmium-nanocluster; CCK-8, cell counting kit-8; TUNEL, terminal deoxynucleotidyl transferase dUTP nick end labeling.
Tables 1 and 2 illustrate the molecular mechanisms through which C. sativus exerts its anti-breast cancer properties. The anti-cancer mechanisms of C. sativus and its constituents have been categorized as following:
Induction of Apoptosis
Apoptosis is a crucial mechanism for eliminating cancer cells. C. sativus and its constituents, including crocetin, crocin, and safranal, have been shown to induce apoptosis in breast cancer cells through different pathways:
• Bcl-2 family proteins: The Bcl-2 family proteins have an important role in apoptosis regulation, consisting of both anti-apoptotic proteins (eg, Bcl-xL, Bcl-2), and pro-apoptotic proteins (eg, Bak, Bax). 90 The balance between these proteins indicates the cell’s fate to die or survive. Studies have shown that metabolites of C. sativus are effective options for modulating the level of this protein family expression.70,78
a) Reduced of anti-apoptotic proteins expression: The metabolites of C. sativus have demonstrated the downregulation of the anti-apoptotic proteins expression like Bcl-2, so decreasing the resistance of cell to pro-apoptotic signals. This action is important for the apoptotic process promotion, as enhanced Bcl-2 levels often contribute to cancer cell proliferation and survival.
b) Enhancement of pro-apoptotic factors expression: The metabolites of C. sativus increase the pro-apoptotic proteins expression such as Bax, associating with a shift in the balance of pro-apoptotic/anti-apoptotic. Bax induces mitochondrial membrane permeabilization favors the release of cytochrome C into the cytosol. Cytochrome C release then proceeds to activate a cascade of events favoring apoptosis through the intrinsic apoptotic pathway.
c) Mitochondrial membrane permeabilization: The reduced levels of Bcl-2 and elevated levels of Bax lead to pore formation in the mitochondrial membranes, thereby permitting the passage of apoptosis-inducing factors to initiate an activation of downstream caspases.70,78
• Activation of executioner caspases: Caspases form the family of cysteine proteases, crucially involved in the apoptotic execution phase; For instance, caspase-3 is an executioner caspase the activation of which commits a cell to apoptosis. Induction of caspase-3 activity is therefore also needed for dismantling cellular components and amplifying the apoptotic signal through a positive feedback mechanism. The caspase-3 activation proteolytically cleaves different cellular substrates and causes morphological changes in apoptosis, including membrane blebbing, chromatin condensation, and DNA fragmentation. 91 It has been documented that C. sativus can enhance the activity of these types of caspases thereby accelerating the apoptotic event in breast cancer cells. This action is very important in targeting cancerous cells and halting tumor progression.62,65
Inhibition of Cell Proliferation
In recent times, much attention has been paid to the anti-proliferative effects of C. sativus and its constituents, particularly concerning breast cancer. The phenomenon prohibits cancer cell proliferation through several interconnected pathways. Two important mechanisms in this regard are cell cycle arrest and regulation of oncogenes and tumor suppressor genes.
Cell cycle arrest: C. sativus and its active constituents, have been indicated to induce apoptosis in several tumoral cells such as breast cancer cells. Apoptosis clears damaged or unwanted cells and also prevents their proliferation. Researchers demonstrated that crocin triggers apoptotic pathways, which are essential for stopping the cell cycle in cancerous cells, consequently contributing to its anticancer actions. Crocin notably affects key regulators of the cell cycle, especially p21Cip1 and cyclin D1. In N-Nitroso-N-Methylurea-induced breast cancer models, treatment with crocin caused the downregulation of cyclin D1, a protein that promotes cell cycle progression. Concurrently, it suppressed the p21Cip1 expression, a cyclin-dependent kinase inhibitor that can stop the cell cycle. These actions contribute to cell cycle arrest, especially in the G1 phase, consequently tumor growth inhibition. The mechanisms by which crocin causes cell cycle arrest include different signaling pathways modulation. For instance, crocin has been reported to inhibit telomerase activity and downregulation of NF-kB expression, both of which participate in survival and cell proliferation. By interfering with these pathways, crocin efficiently leads to apoptosis and cell cycle arrest in breast cancer cells.47,50
Regulation of oncogenes and tumor suppressors: The regulation of tumor suppressor genes and oncogenes is an important dimension of cancer biology. The p53 gene is commonly described as the “guardian of the genome” because of its significant function in controlling the cell cycle and genomic integrity. It is a tumor suppressor because it inhibits the growth of tumors by cell cycle arrest to permit repair of the DNA and by inducing apoptosis if the cell is stressed or damaged. If p53 is inactivated or mutated, cancer cells are then permitted to grow without control. 92 Crocin was found to be able to increase the expression of p53 in cancer cells. In breast cancer, that is, in MCF-7 cells, crocin treatment results in a remarkable increase in the p53 levels, indicating that crocin is expected to restore or increase the tumor-suppressing activity of p53. This is crucial because p53 activation may result in apoptosis induction and thus inhibit cancer cell growth. Crocin triggers apoptosis by mitochondrial signaling pathways. Crocin triggers caspase-8, which has been shown to cause Bax conformational change, a pro-apoptotic protein. Bax activation leads to mitochondrial membrane permeabilization, cytochrome c release, and downstream caspase activation, culminating in the death of cells through programed mechanisms. The event is greatly affected by p53, which can regulate the expression and activity of Bax. 46
Anti-Inflammatory Properties
Chronic inflammation is increasingly being identified as an important factor in the development of different cancer types. Chronic inflammation may result in a tumorigenic microenvironment, which is induced by a perpetual cycle of tissue damage and repair, in which inflammation leads to genetic changes and increases the proliferation of cells. 93 Inflammatory cells, including neutrophils and macrophages, infiltrate the tumor microenvironment and release growth factors, reactive oxygen species (ROS), and various pro-inflammatory cytokines. Their presence may induce DNA damage and thereby enhance the risk of mutations that would lead to cancer progression. For example, the generation of ROS by inflammation has been implicated in oxidative stress, a condition shown to initiate carcinogenic pathways.93,94 Among other factors, C. sativus’s antiinflammatory characteristics are central to its anti-cancer action:
Cytokine modulation: Research has indicated that C. sativus and its constituents inhibit the production of pro-inflammatory cytokines, including Tumor Necrosis Factor alpha (TNF-α), and so on. The reduction of these inflammatory mediators impacts the likelihood of tumor growth. 51
Suppression of inflammatory pathways: It is also possible that C. sativus and its constituents have a suppressive effect on vital inflammatory mechanisms such as the NF-κB pathway. The anticancer effect of C. sativus is thereby increased as it inhibits the transcription of genes involved in inflammation and cancer progression. 51
Angiogenesis Inhibition
Angiogenesis, the formation of new blood vessels from pre-existing vessels, is one of the biological processes that is very important for tumor growth and metastasis. The continuous need for oxygen and nutrients to support the fast growth of tumors fosters the process of angiogenesis. 95 In physiological conditions, angiogenesis is strictly regulated. However, in cancer, this regulation is usually lost, and there is rampant angiogenesis that supports tumor growth. The tumor microenvironment secretes a number of pro-angiogenic factors, one of the most significant of which is vascular endothelial growth factor (VEGF). VEGF promotes the proliferation and tube formation of endothelial cells, a process through which tumors can grow beyond a minimal size. The importance of angiogenesis in oncology is highlighted by its association with tumor growth. The developing tumor can release other factors to induce angiogenesis as well as lymphangiogenesis (formation of lymph vessels), which further increases its capability to invade local tissues and metastasize to distant locations.95,96 Several studies have proved that C. sativus has the potential to inhibit the angiogenesis of tumoral cells in different ways and potentially inhibit the growth of tumors:
VEGF and VEGFR2 regulation: It has been reported that C. sativus and its constituents can downregulate the expression levels of VEGF and its relevant receptor VEGFR2. This type of inhibition causes the regression of the blood supply needed for the expansion of a tumor, denying it the nutrients transported by blood vessels.58,64
Matrix metalloproteinases (MMPs): Modern medicine offers C. sativus as a possible therapy against matrix metalloproteinases, which facilitate the degradation of the extracellular matrix as well as advanced angiogenesis. Inhibition of MMPs by C. sativus and its constituents may be yet another way to limit the level of angiogenesis in tumors.48,80
Modulation of Signaling Pathways
The anticancer properties of C. sativus and its constituents are also attributable to the modulation of various signaling pathways:
PTEN/AKT1 pathway: PTEN (Phosphatase and Tensin Homolog) is a tumor suppressor gene that functions as a negative regulator of the AKT1 pathway. Where PTEN is present, it inhibits the AKT1 signaling, with the downstream effect of promoting apoptosis and inhibiting uncontrolled cell growth. However, in the majority of cancers, as well as in breast cancer, PTEN is either mutated or downregulated, leading to elevated AKT1 activity and promoting cell survival. A recent study highlights the fact that crocin is a potent inhibitor of the PTEN/AKT1 signaling pathway. The study reveals that crocin treatment induces overexpression of the PTEN gene and underexpression of the AKT1 gene in MCF7 breast cancer cells, thereby reducing cell growth and enhancing apoptosis in breast cancer cells. 59
Synergistic Effects With Other Therapies
Combining C. sativus with other medications in the treatment of breast cancer opens a new horizon of possibilities. Studies indicate that C. sativus can improve the outcomes of standard treatments including chemotherapy and radiotherapy and there were cases emphasizing that:
Chemosensitization: Chemotherapy agents are known to have restricted use in certain cases due to high toxicity profiles. To this effect, C. sativus has been shown to chemosensitize breast cancer cells to certain chemotherapeutics, allowing for lower doses with fewer side effects. This positive outcome may be dependent on the capacity of C. sativus to modulate drug resistance mechanisms.73,84
Combination with high-intensity interval training: Interestingly, based on the results of some studies, the combination of high-intensity interval training with the aqueous extract of C. sativus showed less therapeutic effects in some breast cancer indexes than high-intensity interval training alone.86 -89 For example, Ahmadabadi et al indicated the crocin effect on elevating the Bax/Bcl-2 ratio and the activation of caspase of 4T1 breast cancer-bearing mice. While the combination of high-intensity interval training with C. sativus aqueous extract showed a positive effect on tumor volume reduction, no synergistic effect was observed in apoptotic indices when both strategies were implemented. It is worth noting that the levels of pro- and anti-apoptotic proteins in tumor tissue were found to be lower and higher, respectively, following the combined treatment compared to either high-intensity interval training or C. sativus aqueous extract treatment alone. Collectively, these results suggest that in this study, the combination of high-intensity interval training with C. sativus aqueous extract exhibited higher levels of pro-apoptotic proteins (caspase-3 and Bax) and a decrease in the anti-apoptotic protein Bcl-2 compared to the C. sativus aqueous extract group. This indicates the potential significance of antioxidant supplementation in enhancing antioxidant defenses and acting as a scavenger for exercise-induced reactive oxygen species. 88 Likewise, a recent study showed that administering pomegranate juice as antioxidant supplementation reduced Bcl-2 expression in tumor tissue and enhanced enzymatic antioxidant defenses in skeletal muscle of Copenhagen rats with prostate tumors. However, when combined with exercise training, this effect was prevented. 97 Additionally, another study found that high-intensity interval training improved the anti-inflammatory index (IL-10/TNF-α ratio) in the gastrocnemius skeletal muscle of mice with breast cancer. However, when high-intensity interval training was combined with selenium nanoparticles as antioxidant supplementation, no significant effect on this ratio was observed. 98 Taken together, these findings may support observation of increased pro-apoptotic protein (caspase-3 and Bax) and reduced level of anti-apoptotic Bcl-2 in the HIIT + SAE group compared to the SAE group in this study, suggesting the importance of antioxidant supplementation on the antioxidant defenses as a scavenger of exercise training induced-ROS. C. sativus and its constituents have a high lethal dose (LD50) against normal cells, indicating low toxicity. In conclusion, emerging evidence suggests that C. sativus extract, along with crocin, crocetin, and safranal, selectively targets cancer cells and may possess cancer-preventive properties. Moreover, C. sativus and its constituents are considered non-toxic when administered orally. 99
Toxicology Assessment and Some Reported Side Effects Regarding Consumption of C. sativus and Its Constituents
Although the evaluation of clinical trial studies is not the subject of the current study, and the animal studies included in this review did not report any specific side effects regarding applying C. sativus and its constituents, there are some other studies that have addressed concerns about the safety of this medicinal plant usage,100,101 and also numerous interventional researches that reported whether any adverse events had occurred.102 -111
In a subchronic investigation, the safety of ethanolic extract of C. sativus was evaluated in mice at different doses up to 5 g/kg body weight for 8 weeks continuously. This research indicated that this herbal extract was non-toxic, as no any hepatic or renal toxicity and no mortality was observed. 100 The safety of C. sativus (400 mg/day for 7 days) was evaluated in healthy subjects. The results of the study showed that while applying C. sativus caused changes in biochemical and hematological parameters, these changes were within normal limits and there were no clinical complications. 101
Several clinical trials are evaluating the efficacy of C. sativus against different disorders in which side effects were reported. based on these studies the most commonly reported adverse events were usually self-limiting, minor, and restricted to gastrointestinal disturbances such as digestive problems, nausea, constipation, vomiting, and diarrhea, some limited neurological or psychological problems like headache, dizziness, and insomnia and some other complications such as dry mouth, and increased urination.102 -106 However, there are a considerable number of trials that have reported no side effects associated with C. sativus consumption.107 -111
Conclusion
In the present systematic review, the potential of C. sativus and its constituents in the treatment of breast cancer has been comprehensively assessed. The findings of our study suggest that certain compounds, particularly crocin and crocetin, have significant anticancer properties. In particular, crocin at (150-200 mg/kg once a week for 4 weeks in animal models) provided the highest level of evidence of efficacy in preclinical research, indicating its potential for further investigation.
The primary mechanisms proposed for the anticancer activities of C. sativus and its constituents are induction of apoptosis, which causes programed cell death in cancer cells, and modulation of the cell cycle, which is effective in suppressing cancer cell growth. In addition, the anti-inflammatory activity of C. sativus helps decrease inflammation in the tumor microenvironment, which can lead to reduced tumor growth. These mechanisms represent the different ways in which saffron exerts its anticancer activity.
Given the promising findings of preclinical research, clinical trials are warranted to evaluate the therapeutic potential of C. sativus in the treatment of breast cancer. This review not only emphasizes the potential of saffron as an anticancer agent, but also supports the necessity of further research efforts to identify optimal dosing schedules and treatment regimens. In summary, C. sativus is a potential candidate in the treatment of breast cancer, and further studies are necessary to fully elucidate its therapeutic effects and mechanisms of action.
Methodological Quality Assessment
Our quality assessment of in vivo studies, as depicted in Figure 2, reveals that the most commonly identified biases are related to blinding, randomization, and detection areas that receive insufficient attention in animal studies.

Classification based on different types of bias incorporated in the included animal research.
Limitations, Future Research Needs and Priorities
A major limitation identified is the lack of clinical trials. All studies included in the review were preclinical, focusing on in vitro and in vivo research. This absence highlights the urgent need for well-structured clinical trials to assess the efficacy and safety of C. sativus and its metabolites in human populations. The reviewed studies displayed considerable variability in methodologies, complicating the comparison of results. Future research should aim for standardized protocols to ensure consistency and reliability in findings. This includes establishing clear definitions for optimal dosages and treatment regimens for C. sativus extracts. The review emphasizes the importance of determining optimal effective doses from both therapeutic and economic perspectives. Future studies should incorporate cost-effectiveness analyses to evaluate the viability of C. sativus and its constituents as a treatment option in clinical settings, ensuring that it is not only effective but also economically feasible. Future research should also emphasize comparative studies of C. sativus and its bioactive constituents with other well-studied natural products, such as ginger (6-gingerol) and resveratrol, to determine relative efficacy, mechanisms of action, and potential therapeutic interactions in cancer models. It should be noted that this systematic review has not been registered in the International Prospective Register of Systematic Reviews (PROSPERO).
Supplemental Material
sj-docx-1-ict-10.1177_15347354251361450 – Supplemental material for Efficacy of Saffron (Crocus sativus L.) and Its Constituents on Breast Cancer, a Systematic Review of Preclinical Studies and Potential Therapeutic Mechanisms
Supplemental material, sj-docx-1-ict-10.1177_15347354251361450 for Efficacy of Saffron (Crocus sativus L.) and Its Constituents on Breast Cancer, a Systematic Review of Preclinical Studies and Potential Therapeutic Mechanisms by Fatemeh Sadat Hasheminasab and Maryam Azimi in Integrative Cancer Therapies
Footnotes
Author Contributions
Both authors have contributed to the research conception and design. Selection of articles, and extracting study data were performed by H FS, and A M. H FS wrote the first draft of the manuscript. Both authors commented on previous versions of the manuscript and approved the final version.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Data Availability Statement
All acquired data are included in this paper and supplementary file. Further information can be directed to the corresponding author.
Supplemental Material
Supplemental material for this article is available online.
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
