The Effects of Green Tea Consumption on Incidence of Breast Cancer and Recurrence of Breast Cancer: A Systematic Review and Meta-analysis

The interplay of exercise and green tea: a new road in cancer therapy

Exercise is one of the most important activities for every individual due to its proven health beneficials. Several investigations have highlighted the advantageous impacts of aerobic exercise, largely attributed to its capacity to enhance the body's capability to defend against threats against oxidative stress. The information currently accessible suggests that adding regular aerobic exercise to a daily routine greatly decreases the chances of developing serious cancer and passing away. An unevenness in the levels of free radicals and the body's antioxidant defenses, made up of enzyme and non-enzyme antioxidants, results in oxidative pressure. Generally, an imbalance in the levels of oxidative stress triggers the creation of harmful reactive oxygen or nitrogen compounds, causing the development or progression of numerous ailments, including cancer. The equilibrium between pro-oxidant and antioxidant substances is a direct indicator of this imbalance. Green tea and its derivatives are rich sources of bioactive substances such as flavonoids and polyphenols which possess antioxidant abilities. Moreover, modulation of epigenetic targets as well as inflammatory pathways including ERK1/2 and NF-κB are other proposed mechanisms for its antioxidant activity. Recent studies demonstrate the promise of green tea as an antioxidant, showing its ability to decrease the likelihood of developing cancer by impacting actions like cell growth, blood vessel formation, and spread of cancer cells. This summary will concentrate on the complex network of different pathways related to physical activity and consumption of green tea. In particular, the focus of this research will be on examining how oxidative stress contributes to health and investigating the potential antioxidant properties of green tea, and the interconnected relationship between exercise and green tea in the treatment of cancer. Elucidation of these different pathways would help scientists for development of better therapeutic targets and further increase of current anticancer agents efficiency.

Nutrition Intervention and Microbiome Modulation in the Management of Breast Cancer

Breast cancer (BC) is one of the most common cancers worldwide and a leading cause of cancer-related deaths among women. The escalating incidence of BC underscores the necessity of multi-level treatment. BC is a complex and heterogeneous disease involving many genetic, lifestyle, and environmental factors. Growing evidence suggests that nutrition intervention is an evolving effective prevention and treatment strategy for BC. In addition, the human microbiota, particularly the gut microbiota, is now widely recognized as a significant player contributing to health or disease status. It is also associated with the risk and development of BC. This review will focus on nutrition intervention in BC, including dietary patterns, bioactive compounds, and nutrients that affect BC prevention and therapeutic responses in both animal and human studies. Additionally, this paper examines the impacts of these nutrition interventions on modulating the composition and functionality of the gut microbiome, highlighting the microbiome-mediated mechanisms in BC. The combination treatment of nutrition factors and microbes is also discussed. Insights from this review paper emphasize the necessity of comprehensive BC management that focuses on the nutrition-microbiome axis.

Phytonutrients and outcomes following breast cancer: a systematic review and meta-analysis of observational studies

BACKGROUND

Phytonutrient intakes may improve outcomes following breast cancer, but the impact of postdiagnosis introduction vs established prediagnostic exposure as well as optimum doses has not been established. Evidence from observational studies for key exposures was evaluated, including dosage and intake time frames.

METHODS

MEDLINE, EMBASE, CINAHL, Cochrane Library, ClinicalTrials.gov, and the ISRCTN registry were searched for prospective and retrospective observational studies investigating the impact of soybean, lignans, cruciferous (cabbage-family) vegetables, green tea, or their phytonutrients on breast cancer survival outcomes. A random-effects model was used to calculate summary hazard ratios (HRs) and 95% confidence intervals (CIs). Nonlinear dose-response analyses were conducted using restricted cubic splines.

RESULTS

Thirty-two articles were included. Soy isoflavones were associated with a 26% reduced risk of recurrence (HR = 0.74, 95% CI = 0.60 to 0.92), particularly among postmenopausal (HR = 0.72, 95% CI = 0.55 to 0.94) and estrogen receptor-positive survivors (HR = 0.82, 95% CI = 0.70 to 0.97), with the greatest risk reduction at 60 mg/day. In mortality outcomes, the reduction was mostly at 20 to 40 mg/day. Soy protein and products were inversely associated with cancer-specific mortality for estrogen receptor-positive disease (HR = 0.75, 95% CI = 0.60 to 0.92). An inverse association was observed for serum or plasma enterolactone, measured prediagnosis and early postdiagnosis, with cancer-specific mortality (HR = 0.72, 95% CI = 0.58 to 0.90) and all-cause mortality (HR = 0.69, 95% CI = 0.57 to 0.83). No effects were observed for cruciferous vegetables. There was a 44% reduced risk of recurrence with prediagnostic green tea for stage I and II breast cancer (HR = 0.56, 95% CI = 0.38 to 0.83).

CONCLUSIONS

Soy, enterolactone, and green tea demonstrated significant risk reductions in outcomes following breast cancer. Evidence is needed regarding the impact of postdiagnostic introduction or substantial increase of these exposures.

Natural products derived from medicinal plants and microbes might act as a game-changer in breast cancer: a comprehensive review of preclinical and clinical studies

Breast cancer (BC) is the most prevalent neoplasm among women. Genetic and environmental factors lead to BC development and on this basis, several preventive - screening and therapeutic interventions have been developed. Hormones, both in the form of endogenous hormonal signaling or hormonal contraceptives, play an important role in BC pathogenesis and progression. On top of these, breast microbiota includes both species with an immunomodulatory activity enhancing the host's response against cancer cells and species producing proinflammatory cytokines associated with BC development. Identification of novel multitargeted therapeutic agents with poly-pharmacological potential is a dire need to combat advanced and metastatic BC. A growing body of research has emphasized the potential of natural compounds derived from medicinal plants and microbial species as complementary BC treatment regimens, including dietary supplements and probiotics. In particular, extracts from plants such as Artemisia monosperma Delile, Origanum dayi Post, Urtica membranacea Poir. ex Savigny, Krameria lappacea (Dombey) Burdet & B.B. Simpson and metabolites extracted from microbes such as Deinococcus radiodurans and Streptomycetes strains as well as probiotics like Bacillus coagulans and Lactobacillus brevis MK05 have exhibited antitumor effects in the form of antiproliferative and cytotoxic activity, increase in tumors' chemosensitivity, antioxidant activity and modulation of BC - associated molecular pathways. Further, bioactive compounds like 3,3'-diindolylmethane, epigallocatechin gallate, genistein, rutin, resveratrol, lycopene, sulforaphane, silibinin, rosmarinic acid, and shikonin are of special interest for the researchers and clinicians because these natural agents have multimodal action and act via multiple ways in managing the BC and most of these agents are regularly available in our food and fruit diets. Evidence from clinical trials suggests that such products had major potential in enhancing the effectiveness of conventional antitumor agents and decreasing their side effects. We here provide a comprehensive review of the therapeutic effects and mechanistic underpinnings of medicinal plants and microbial metabolites in BC management. The future perspectives on the translation of these findings to the personalized treatment of BC are provided and discussed.

Evolution of Natural Product Scaffolds as Potential Proteasome Inhibitors in Developing Cancer Therapeutics

Homeostasis between protein synthesis and degradation is a critical biological function involving a lot of precise and intricate regulatory systems. The ubiquitin-proteasome pathway (UPP) is a large, multi-protease complex that degrades most intracellular proteins and accounts for about 80% of cellular protein degradation. The proteasome, a massive multi-catalytic proteinase complex that plays a substantial role in protein processing, has been shown to have a wide range of catalytic activity and is at the center of this eukaryotic protein breakdown mechanism. As cancer cells overexpress proteins that induce cell proliferation, while blocking cell death pathways, UPP inhibition has been used as an anticancer therapy to change the balance between protein production and degradation towards cell death. Natural products have a long history of being used to prevent and treat various illnesses. Modern research has shown that the pharmacological actions of several natural products are involved in the engagement of UPP. Over the past few years, numerous natural compounds have been found that target the UPP pathway. These molecules could lead to the clinical development of novel and potent anticancer medications to combat the onslaught of adverse effects and resistance mechanisms caused by already approved proteasome inhibitors. In this review, we report the importance of UPP in anticancer therapy and the regulatory effects of diverse natural metabolites, their semi-synthetic analogs, and SAR studies on proteasome components, which may aid in discovering a new proteasome regulator for drug development and clinical applications.

Recurrence of Breast Cancer After Primary Treatment: A Matched Comparison Study of Disease-Free Survival in Women Who Do and Do Not Receive Adjunctive Naturopathic Oncology Care

PURPOSE

To compare disease free survival experienced by women who received usual oncologic care compared to a cohort of women who received naturopathic oncology care in addition to usual care.

METHODS

Women with breast cancer who received naturopathic oncology (NO) care in Western Washington State (WA) (N = 176) were recruited to a prospective study of clinical health-related quality of life outcomes and then matched to women who received usual care (UC) only (N = 334).

RESULTS

Among 510 women with breast cancer stages 1 to 3, a total of 50 women (10%) experienced a disease-free survival (DFS) ending event within the observation period; 23 (6.8% of those in the UC cohort, and 27 (15.3% of those in the NO cohort (P < .05). Although, women in the 2 cohorts received similar surgical, chemotherapy, and radiation treatment, women with breast cancer who received naturopathic oncology adjunctive care were less likely to use anti-estrogen therapy, and experienced poorer DFS (logrank test, P < .05). However, differences in DFS could not be shown to be due to cohort differences in anti-estrogen therapy, baseline HRQOL, or naturopathic oncology therapies prescribed. The stage 3 women in the naturopathic oncology group had more advanced disease at diagnosis. They were more likely to have 5 or more metastatic lymph nodes at baseline (18.5%) compared to their usual care matched control group (13%). Women in the naturopathic oncology group also had higher grade tumors at diagnosis.

CONCLUSIONS

Results show that recurrence of breast cancer was associated with more advanced malignant lymph node involvement; and that naturopathic oncology services provided in 2009-2015 did not improve disease-free survival in these high-risk breast cancer patients.

Green tea and cancer and cardiometabolic diseases: a review of the current epidemiological evidence

Green tea is commonly consumed in China, Japan, and Korea and certain parts of North Africa and is gaining popularity in other parts of the world. The aim of this review was to objectively evaluate the existing evidence related to green tea consumption and various health outcomes, especially cancer, cardiovascular disease and diabetes. This review captured evidence from meta-analyses as well as expert reports and recent individual studies. For certain individual cancer sites: endometrial, lung, oral and ovarian cancer, and non-Hodgkins lymphoma the majority of meta-analyses observed an inverse association with green tea. Mixed findings were observed for breast, esophageal, gastric, liver and a mostly null association for colorectal, pancreatic, and prostate cancer. No studies reported adverse effects from green tea related to cancer although consuming hot tea has been found to possibly increase the risk of esophageal cancer and concerns of hepatotoxity were raised as a result of high doses of green tea. The literature overall supports an inverse association between green tea and cardiovascular disease-related health outcomes. The evidence for diabetes-related health outcomes is less convincing, while the included meta-analyses generally suggested an inverse association between green tea and BMI-related and blood pressure outcomes. Fewer studies investigated the association between green tea and other health outcomes such as cognitive outcomes, dental health, injuries and respiratory disease. This review concludes that green tea consumption overall may be considered beneficial for human health.

Medicinal Herbs Used in Traditional Management of Breast Cancer: Mechanisms of Action

Background: Breast cancer is one of the principal causes of death among women and there is a pressing need to develop novel and effective anti-cancer agents. Natural plant products have shown promising results as anti-cancer agents. Their effectiveness is reported as decreased toxicity in usage, along with safety and less recurrent resistances compared with hormonal targeting anti-cancer agents. Methods: A literature search was conducted for all English-language literature published prior to June 2020. The search was conducted using electronic databases, including PubMed, Embase, Web of Science, and Cochrane Library. The search strategy included keywords such as breast cancer, herbs, anti-cancer biologically active components, clinical research, chemotherapy drugs amongst others. Results: The literature provides documented evidence of the chemo-preventative and chemotherapeutic properties of Ginseng, garlic (Allium sativum), Black cohosh (Actaea racemose), Tumeric (Curcuma longa), Camellia sinenis (green tea), Echinacea, Arctium (burdock), Flaxseed (Linum usitatissimum) and Black Cumin (Nigella sativa). Conclusions: The nine herbs displayed anti-cancer properties and their outcomes and mechanisms of action include inhibition of cell proliferation, angiogenesis and apoptosis as well as modulation of key intracellular pathways. However, more clinical trials and cohort human studies should be conducted to provide key evidence of their medical benefits.

Breast Cancer Primary Prevention and Diet: An Umbrella Review

Introduction: Many studies have been published, but none have pooled the useful evidence available in the literature to produce guidelines and health policies promoting healthy eating styles to prevent breast cancer (BC). The present study aimed to summarize the evidence produced to date, taking a judicious, critical approach to the quality of the studies analyzed. Methods: An umbrella review method was adopted, which is a systematic review of second-level studies, meta-analyses and literature reviews. Results: In all, 48 studies were considered: 32 meta-analyses, 4 pooled analyses, 5 systematic reviews, and 7 qualitative reviews. A higher intake of total meat, or red or processed meats, or foods with a high glycemic index, or eggs would seem to be associated with a higher risk of BC. Some foods, such as vegetables, would seem instead to have an inverse association with BC risk. One meta-analysis revealed an inverse association between citrus fruit and mushroom consumption and BC. Some nutrients, such as calcium, folate, vitamin D, lignans and carotenoids, also seem to be inversely associated with BC risk. The evidence is still conflicting as concerns exposure to other dietary elements (e.g., polyunsaturated fatty acids, dairy foods). Conclusion: Nutrition is one of the most modifiable aspects of people's lifestyles and dietary choices can affect health and the risk of cancer. Overall, adhering to a healthy eating style may be associated with a significant reduction in the risk of BC.

Ultrasound-assisted extraction of some branded tea: Optimization based on polyphenol content, antioxidant potential and thermodynamic study

Tea is one of the top beverages used around the world every day, which contains a high amount of polyphenols and antioxidants. The main aim of this research is to quantify some marketed black tea (Rabea, Lipton, Alkbous, Green gold and Haritham) for phenolic contents and antioxidant potential evaluation by ultrasound solvent extraction and was compared with conventional extraction. Ultrasonic extraction was optimized by considering frequencies (26 kHz, 40 kHz), temperature (30, 40 and 50 °C), and power (30, 40 and 50%) at a fixed time of 30 min. In both the ultrasonic frequencies, 40 °C temperature and 40% power combination exhibited highest cumulative yield (mg/100 g DW), total phenolic content (mg gallic acid/g DW), flavonoids (mg/g DW) and DPPH radical scavenging activity (%) in all branded tea. Within each brand of tea, at any temperature-power combination at particular frequency results were not significantly different. But, at a similar condition of temperature power results were found significantly different between two frequencies. Furthermore, ultrasonic extraction process was analyzed thermodynamically by selecting some basic parameters. Thermodynamics results showed the extraction process was feasible, spontaneous and irreversible. Also, 26 kHz ultrasonic probe is more appropriate for the extraction purpose and thermodynamically more acceptable as compared to 40 kHz ultrasonic bath. Moreover, Haritham was selected as the best tea brand due to its high polyphenol contents and antioxidant potential.

Inflammation, a Double-Edge Sword for Cancer and Other Age-Related Diseases

Increasing evidence from diverse sources during the past several years has indicated that long-term, low level, chronic inflammation mediates several chronic diseases including cancer, arthritis, obesity, diabetes, cardiovascular diseases, and neurological diseases. The inflammatory molecules and transcription factors, adhesion molecules, AP-1, chemokines, C-reactive protein (CRP), cyclooxygenase (COX)-2, interleukins (ILs), 5-lipooxygenase (5-LOX), matrix metalloproteinases (MMPs), nuclear factor (NF)-kB, signal transducer and activator of transcription 3 (STAT3), tumor necrosis factor (TNF), and vascular endothelial growth factor (VEGF) are molecular links between inflammation and chronic diseases. Thus, suppression of inflammatory molecules could be potential strategy for the prevention and therapy of chronic diseases. The currently available drugs against chronic diseases are highly expensive, minimally effective and produce several side effects when taken for long period of time. The focus of this review is to discuss the potential of nutraceuticals derived from “Mother Nature” such as apigenin, catechins, curcumin, ellagic acid, emodin, epigallocatechin gallate, escin, fisetin, flavopiridol, genistein, isoliquiritigenin, kaempferol, mangostin, morin, myricetin, naringenin, resveratrol, silymarin, vitexin, and xanthohumol in suppression of these inflammatory pathways. Thus, these nutraceuticals offer potential in preventing or delaying the onset of chronic diseases. We provide evidence for the potential of these nutraceuticals from pre-clinical and clinical studies.

Mechanisms of Phytonutrient Modulation of Cyclooxygenase-2 (COX-2) and Inflammation Related to Cancer

The link between chronic inflammation and cancer involves cytokines and mediators of inflammatory pathways. Cyclooxygenase-2 (COX-2), a key enzyme in fatty acid metabolism, is upregulated during both inflammation and cancer. COX-2 is induced by pro-inflammatory cytokines at the site of inflammation and enhanced COX-2-induced synthesis of prostaglandins stimulates cancer cell proliferation, promotes angiogenesis, inhibits apoptosis, and increases metastatic potential. As a result, COX-2 inhibitors are a subject of intense research interest toward potential clinical applications. Epidemiological studies highlight the potential benefits of diets rich in phytonutrients for cancer prevention. Plants contain numerous phytonutrient secondary metabolites shown to modulate COX-2. Studies have shown that these metabolites, some of which are used in traditional medicine, can reduce inflammation and carcinogenesis. This review describes the molecular mechanisms by which phytonutrients modulate inflammation, including studies of carotenoids, phenolic compounds, and fatty acids targeting various inflammation-related molecules and pathways associated with cancer. Examples of pathways include those of COX-2, mitogen-activated protein kinase kinase kinase, mitogen-activated protein kinase, pro-inflammatory cytokines, and transcription factors like nuclear factor kappa B. Such phytonutrient modulation of COX-2 and inflammation continue to be explored for applications in the prevention and treatment of cancer.

Yellow tea (Camellia sinensis L.), a promising Chinese tea: Processing, chemical constituents and health benefits

Yellow tea, also known as huángchá in Chinese, is a lightly fermented tea unique to China. As a rare and precious variety of tea, it has gained increasing popularity in recent years because of its pleasant mellow taste and known health benefits such as anti-oxidation, anti-inflammation and anti-cancer properties. Yellow tea is similar to green tea in many ways. The initial production process of both teas is the same, but the production of yellow tea requires additional steps. A unique procedure called "sealed yellowing" is always involved in yellow tea processing to increase the oxidation level and remove the characteristic grassy smell associated with green tea while still preserving its health benefits. Compared to other types of teas, yellow tea is much less well-known and studied. In this review, the history and classification of yellow tea are introduced. The processing procedures, including detailed information about "sealed yellowing", are presented. The bioactive chemical compounds common in various types of teas or unique to yellow tea are discussed. Finally, future needs in research and development of yellow tea are proposed.

Phytotherapy and Nutritional Supplements on Breast Cancer

Breast cancer is the most frequent type of nonskin malignancy among women worldwide. In general, conventional cancer treatment options (i.e., surgery, radiotherapy, chemotherapy, biological therapy, and hormone therapy) are not completely effective. Recurrence and other pathologic situations are still an issue in breast cancer patients due to side effects, toxicity of drugs in normal cells, and aggressive behaviour of the tumours. From this point of view, breast cancer therapy and adjuvant methods represent a promising and challenging field for researchers. In the last few years, the use of some types of complementary medicines by women with a history of breast cancer has significantly increased such as phytotherapeutic products and nutritional supplements. Despite this, the use of such approaches in oncologic processes may be problematic and patient's health risks can arise such as interference with the efficacy of standard cancer treatment. The present review gives an overview of the most usual phytotherapeutic products and nutritional supplements with application in breast cancer patients as adjuvant approach. Regardless of the contradictory results of scientific evidence, we demonstrated the need to perform additional investigation, mainly well-designed clinical trials in order to establish correlations and allow for further validated outcomes concerning the efficacy, safety, and clinical evidence-based recommendation of these products.

Breast cancer chemopreventive and chemotherapeutic effects of Camellia Sinensis (green tea): an updated review

Introduction

Camellia sinensis belongs to the plant family of Theaceae, native to East Asia, the Indian Subcontinent and Southeast Asia, but naturalized in many parts of the world. The aim of this study was to overview its anti-breast cancer chemopreventive and chemotherapeutic effects. This review article is aimed to overview breast cancer chemopreventive and chemotherapeutic effects of Camellia sinensis (green tea).

Methods

This review article was carried out by searching studies in PubMed, Medline, Web of Science, and IranMedex databases. The initial search strategy identified around 108 references. In this study, 68 studies were accepted for further screening, and met all our inclusion criteria [in English, full text, chemopreventive and chemotherapeutic effects of Camellia sinensis and dated mainly from the year 1999 to 2016. The search terms were Camellia sinensis, chemopreventive, chemotherapeutic properties, pharmacological effects.

Result

The result of this study suggested that the catechin available in Camellia sinensis has properties which can prevent and treat breast cancer. It has also been shown to inhibit proliferation of breast cancer cells and to block carcinogenesis. It was found that increased Camellia sinensis consumption may lower the risk of breast cancer. Camellia sinensis intake was shown to reduce the risk of breast cancer incidence. In addition, potential breast cancer chemopreventive effect of Camellia sinensis both in vivo and in vitro was highly confirmed. However, the evidence of low effect and no effect was observed. More clinical trial studies are needed to prove its anti-breast cancer activity decisively.

Conclusion

Camellia sinensis is broadly utilized as a part of customary medication since antiquated time because of its cost adequacy, and fewer reaction properties. The studies demonstrated anti-breast cancer activity of Camellia sinensis and its component by adjusting cell signaling pathways such as angiogenesis, apoptosis, and transcription factor. Furthermore, Camellia sinensis and its chemical compound was shown to be extremely useful in the development of novel anticancer medications.

Camellia sinensis Mediated Enhancement of Humoral Immunity to Particulate and Non-particulate Antigens

The most common drinking beverage in large portion of the world is Camellia sinensis (green tea). In the present study, we evaluated the adjuvant effect of green tea and tea polyphenols to particulate and non-particulate antigens. BALB/c mice were immunized with particulate and non-particulate antigens. Modulation of immunoglobulin-secreting splenocytes, IgG-mediated and IgM-mediated immunity, was evaluated by hemolytic plaque assay and enzyme-linked immunosorbent assay, respectively. Dose-dependent response of tea polyphenols was also assayed. Phenolic content was measured in crude preparations of green tea. We observed a stimulatory effect of green tea preparations on humoral immune response mediated by the increased number of antibody-secreted cells in spleen. A significant increase in IgM-mediated and IgG-mediated immune response to non-particulate antigen was also observed in green tea-treated animals. A dose-dependent adjuvant effect was seen in the case of tea polyphenols for a longer period of time compared with crude tea preparations. This study indicates polyphenols as major constituents responsible for the enhanced and sustained adjuvant activity of green tea. We suggest that tea polyphenols might be considered for real-life evaluation during adjuvant-mediated vaccination trial programs.

Tea and human health: biomedical functions of tea active components and current issues

Originating in China, tea and tea planting have spread throughout the world since the middle of the Tang dynasty. Now people from 160 countries in the world are accustomed to tea drinking. A brief history of tea's medicinal role in China and its spread to the world are introduced. The effectiveness of tea active components and tea drinking on major human diseases, including cancer, metabolic syndrome, cardiovascular disease, and neurodegenerative diseases, is discussed. Also presented are some related issues, such as the bioavailability of tea active components, the new formulations of tea polyphenols, and the safety for consumers of dietary supplements containing tea polyphenols.

Multifunctional T Lymphocytes Generated After Therapy With an Antitumor Gallotanin-Rich Normalized Fraction Are Related to Primary Tumor Size Reduction in a Breast Cancer Model

Natural compounds are promising sources for anticancer therapies because of their multifunctional activity and low toxicity. Although the host immune response (IR) is clearly implicated in tumor control, the relationship between natural therapies and IR has not yet been elucidated. The present work evaluates IR induction after treatment with a gallotannin-rich fraction from Caesalpinia spinosa (P2Et). Breast tumor 4T1 cells were used to evaluate antitumor properties and IR activation. Apoptosis and expression of immunogenic cell death (ICD) markers were assessed in vitro, whereas IR and postvaccination tumor evolution were assessed in vivo. P2Et fraction induced apoptotic cell death, displaying phosphatidylserine externalization and DNA fragmentation. ICD markers such as calreticulin, high-mobility group box 1 translocation from nuclei to cytoplasm, and ATP secretion were observed. Primary tumor control was improved by vaccination with P2Et-pretreated 4T1 cells (t-P2Et), yielding long-lasting ex vivo multifunctional CD4+ and CD8+ T lymphocytes (interleukin [IL]-2+, tumor necrosis factor [TNF]-α+, interferon [IFN]-γ+) that secrete IL-2, TNF-α, IL-4, IL-5, and IFN-γ after specific 4T1 cell stimulation. The present study constitutes the first demonstration of a long-lasting antitumor IR induction and primary tumor reduction induced by a complex natural fraction. These data reveal the potential use of this fraction as an adjuvant in breast cancer treatment.

Multifunctional T Lymphocytes Generated After Therapy With an Antitumor Gallotanin-Rich Normalized Fraction Are Related to Primary Tumor Size Reduction in a Breast Cancer Model

Natural compounds are promising sources for anticancer therapies because of their multifunctional activity and low toxicity. Although the host immune response (IR) is clearly implicated in tumor control, the relationship between natural therapies and IR has not yet been elucidated. The present work evaluates IR induction after treatment with a gallotannin-rich fraction from Caesalpinia spinosa (P2Et). Breast tumor 4T1 cells were used to evaluate antitumor properties and IR activation. Apoptosis and expression of immunogenic cell death (ICD) markers were assessed in vitro, whereas IR and postvaccination tumor evolution were assessed in vivo. P2Et fraction induced apoptotic cell death, displaying phosphatidylserine externalization and DNA fragmentation. ICD markers such as calreticulin, high-mobility group box 1 translocation from nuclei to cytoplasm, and ATP secretion were observed. Primary tumor control was improved by vaccination with P2Et-pretreated 4T1 cells (t-P2Et), yielding long-lasting ex vivo multifunctional CD4+ and CD8+ T lymphocytes (interleukin [IL]-2+, tumor necrosis factor [TNF]-α+, interferon [IFN]-γ+) that secrete IL-2, TNF-α, IL-4, IL-5, and IFN-γ after specific 4T1 cell stimulation. The present study constitutes the first demonstration of a long-lasting antitumor IR induction and primary tumor reduction induced by a complex natural fraction. These data reveal the potential use of this fraction as an adjuvant in breast cancer treatment.

Expression profiling of genes modulated by estrogen, EGCG or both in MCF-7 breast cancer cells

(−)-Epigallocatechin-3-gallate (EGCG) is one of the most potent and the most studied green tea catechin. Reports on mechanisms of EGCG action and its cellular targets are plenty. Compelling evidences in the literature in favor of ER being one of its targets suggest that EGCG may have a significant impact on estrogen regulated gene expression. Despite the possible implications on breast cancer chemoprevention or therapy, this aspect of EGCG action has not been adequately investigated. In order to address this issue, we have obtained gene expression profiles of MCF-7 breast cancer cells treated with ethanol (vehicle control) and those treated with estrogen, EGCG or both, using microarrays. Here, we have presented in detail the design and execution of the microarray experiment, quality control checks and analysis of microarray data. The utility and importance of the data generated in this work have been discussed in the context of the background literature. Our data is available in the Gene Expression Omnibus (GEO) database with the identifier GSE56245.

Green tea compounds in breast cancer prevention and treatment

Breast cancer is the most common cancer among women. In recent years, many in vitro and in vivo studies indicate that green tea possesses anti-cancer effects. The epidemiological studies, however, have produced inconclusive results in humans. Likewise, results from animal models about the preventive or therapeutic effects of green tea components are inconclusive. The mechanisms by which green tea intake may influence the risk of breast cancer in humans remain elusive mechanisms by which green tea intake may influence. Here, we review recent studies of green tea polyphenols and their applications in the prevention and treatment of breast cancer. Furthermore, we discuss the effect of green tea components on breast cancer by reviewing epidemiological studies, animal model studies and clinical trials. At last, we discuss the mechanisms by which green tea components suppress the development and recurrence of breast cancer. A better understanding of the mechanisms will improve the utilization of green tea in breast cancer prevention and therapy and pave the way to novel prevention and treatment strategies for breast cancer.

Commonly used methods of complementary medicine in the treatment of breast cancer

Many patients with cancer look for information on complementary or alternative medicine (CAM) and use various CAM methods. Women with breast cancer are amongst the most avid users. Patients in Europe prefer drug-bound CAM methods, which are prone to side effects and drug interactions. In order to reduce these risks, communication between the patient and the physician on CAM is indispensible. Yet, most patients do not discuss CAM in general and complementary drug therapy in particular with their oncologists and most oncologists themselves are not overly familiar with the topic. This article gives an overview on the most often used CAM methods with regard to breast cancer. The current state of the scientific evidence, the benefits and risks are summarized.

Effects of a green tea extract, Polyphenon E, on systemic biomarkers of growth factor signalling in women with hormone receptor-negative breast cancer

BACKGROUND

Observational and experimental data support a potential breast cancer chemopreventive effect of green tea.

METHODS

We conducted an ancillary study using archived blood/urine from a phase IB randomised, placebo-controlled dose escalation trial of an oral green tea extract, Polyphenon E (Poly E), in breast cancer patients. Using an adaptive trial design, women with stage I-III breast cancer who completed adjuvant treatment were randomised to Poly E 400 mg (n = 16), 600 mg (n = 11) and 800 mg (n = 3) twice daily or matching placebo (n = 10) for 6 months. Blood and urine collection occurred at baseline, and at 2, 4 and 6 months. Biological endpoints included growth factor [serum hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF)], lipid (serum cholesterol, triglycerides), oxidative damage and inflammatory biomarkers.

RESULTS

From July 2007-August 2009, 40 women were enrolled and 34 (26 Poly E, eight placebo) were evaluable for biomarker endpoints. At 2 months, the Poly E group (all dose levels combined) compared to placebo had a significant decrease in mean serum HGF levels (-12.7% versus +6.3%, P = 0.04). This trend persisted at 4 and 6 months but was no longer statistically significant. For the Poly E group, serum VEGF decreased by 11.5% at 2 months (P = 0.02) and 13.9% at 4 months (P = 0.05) but did not differ compared to placebo. At 2 months, there was a trend toward a decrease in serum cholesterol with Poly E (P = 0.08). No significant differences were observed for other biomarkers.

CONCLUSIONS

Our findings suggest potential mechanistic actions of tea polyphenols in growth factor signalling, angiogenesis and lipid metabolism.

Tea consumption and the risk of five major cancers: a dose-response meta-analysis of prospective studies

Background

We conducted a dose–response meta-analysis of prospective studies to summarize evidence of the association between tea consumption and the risk of breast, colorectal, liver, prostate, and stomach cancer.

Methods

We searched PubMed and two other databases. Prospective studies that reported risk ratios (RRs) with 95% confidence intervals (CIs) of cancer risk for ≥3 categories of tea consumption were included. We estimated an overall RR with 95% CI for an increase of three cups/day of tea consumption, and, usingrestricted cubic splines, we examined a nonlinear association between tea consumption and cancer risk.

Results

Forty-one prospective studies, with a total of 3,027,702 participants and 49,103 cancer cases, were included. From the pooled overall RRs, no inverse association between tea consumption and risk of five major cancers was observed. However, subgroup analysis showed that increase in consumption of three cups of black tea per day was a significant risk factor for breast cancer (RR, 1.18; 95% CI, 1.05-1.32).

Conclusion

Ourresults did not show a protective role of tea in five major cancers. Additional large prospective cohort studies are needed to make a convincing case for associations.

A hypothesis on the relationship between tea drinking and sexual activity

As a major beverage in the world, the health benefits of drinking tea have been reported in numerous studies. The effects of green tea are mainly attributed to its polyphenol content, although caffeine, accounting for 2%-4%, appears to be related to the adaptation of mental energy by increasing alertness, attention and cognitive function, as well as elevating mood. L-Theanine, a unique amino acid in tea, has neuroprotective and mood effects. In addition, some studies on functional neuroanatomy and cerebral control of sexual function have demonstrated that the thalamus and hypothalamus play a role in emotional changes, memory and sexual behavior patterns. Our recent epidemiology research has unexpectedly found that tea drinking was positively related with sexual orgasm and sexual satisfaction in female hypertensive patients. We therefore hypothesize that long-term regular consumption of tea may play a role in sexual activity.

Effects of tea consumption on renal function in a metropolitan Chinese population: the Guangzhou biobank cohort study

OBJECTIVE

Green tea consumption has been associated with many prophylactic health benefits. This study examined for the first time associations between tea consumption and renal function in a Chinese population.

DESIGN AND METHODS

Cross-sectional baseline data including demographics, and lifestyle and weekly consumption of green, black, and oolong tea were analyzed from 12,428 ambulatory subjects aged 50 to 85 years (67.3% female) that were randomly selected from the membership list of a community social and welfare association in Guangzhou, China.

INTERVENTION

Associations between tea consumption and renal function were assessed using regression analyses to adjust for potential confounding factors.

MAIN OUTCOME MEASURE

Renal function was assessed using the estimated glomerular filtration rate (eGFR) and in a subcohort of 1,910 participants using a spot urinary albumin-to-creatinine ratio.

RESULTS

Six thousand eight hundred and seventy-two participants drank at least 1 type of tea. Oolong tea consumption was negatively associated with eGFR (β-coefficient -0.019, P = .025), but in a gender-stratified analysis this was not the case. In men, black tea was positively associated with eGFR (β-coefficient 0.037, P = .013), but not in women (β-coefficient -0.002, P = .856). Otherwise, no statistically significant consistent associations between the measures of renal function and consumption of green tea, black tea, or oolong tea individually or total tea consumption were identified.

CONCLUSION

Overall there was no clear evidence to suggest any consistent association between renal function and tea consumption in this large population-based study of older Chinese individuals.

Impact of lifestyle factors on prognosis among breast cancer survivors in the USA

Advances in diagnostic screening and adjuvant therapy have dramatically increased the number of breast cancer survivors in the USA, who may face changes in physical and mental health, social support, quality of life and economics. Women living with breast cancer are increasingly interested in lifestyle modification to decrease the risk of recurrence and mortality while increasing physical and emotional wellbeing. Although organizations such as the American Cancer Society support a healthy diet, frequent physical activity and stress reduction for decreasing breast cancer risk, studies examining the effects of lifestyle on clinical outcomes including survival and prognosis have been inconclusive. With the number of breast cancer survivors predicted to increase to 3.4 million by 2015, it is important to develop effective treatment paradigms that overcome barriers to behavioral modification to improve clinical outcomes and survivorship in breast cancer patients.

Flavonoids and cancer prevention: a review of the evidence

The objective of this work is to review data from epidemiological and preclinical studies addressing the potential benefits of diets based on flavonoids for cancer prevention. Flavonoids are subdivided into subclasses including flavonols, flavones, flavanones, flavan-3-ols, anthocyanidins, and isoflavones. Epidemiological studies suggest dietary intake of flavonoids may reduce the risk of tumors of the breast, colon, lung, prostate, and pancreas. However, some studies have reported inconclusive or even harmful associations. A major challenge in the interpretation of epidemiological studies is that most of the data originate from case-control studies and retrospective acquisition of flavonoid intake. Differences in agricultural, sociodemographics, and lifestyle factors contribute to the heterogeneity in the intake of flavonoids among populations residing in the United States, Europe, and Asia. Dose and timing of exposure may influence the anticancer response to flavonoid-rich diets. A limited number of intervention trials of flavonoids have documented cancer preventative effects. Proposed anticancer mechanisms for flavonoids are inhibition of proliferation, inflammation, invasion, metastasis, and activation of apoptosis. Prospective studies with larger sample sizes are needed to develop biomarkers of flavonoid intake and effect. Mechanistic studies are needed to ascertain how flavonoid-rich diets influence gene regulation for cancer prevention.

Complementary and alternative therapies used by Turkish breast cancer patients undergoing chemotherapy

BACKGROUND

Most breast cancer patients use complementary and alternative medicine (CAM), usually in parallel with their conventional treatments. This study was planned to determine the prevalence and determining factors for use of CAM by breast cancer patients undergoing chemotherapy.

PATIENTS AND METHODS

This descriptive study was carried out between October 2010 and May 2011, and included 96 patients at the Istanbul University Institute of Oncology. The Patient Characteristics form and Complementary and Alternative Medicine Scale were used for data collection. Descriptive and non-parametric tests were performed, and logistic regression analysis was used to predict factors affecting CAM use.

RESULTS

Praying was the most frequently used form of CAM, and most of the herbal supplements used by patients were harmless. Herbal use was higher among patients who had local disease (relative risk (RR) 4.48%, 95% confidence interval (CI) 1.12-17.95), and worship was more common among those who had not undergone surgery (RR 4.66%, 95% CI 1.64-13.20).

CONCLUSION

The CAM approaches used by patients were found to be safe. However, sage and flax seed usage for estrogen-and progesterone-positive patients and exercise for patients with spinal metastasis can be inappropriate approaches. It is important to question and inform patients about CAM use during treatment.

Green Tea and Lung Cancer

Background: Green tea is a beverage widely used by lung cancer patients and the public for its purported anticancer properties. The authors conducted a systematic review of green tea for the treatment and prevention of lung cancer. Methodology: Six electronic databases were searched from inception until November 2011 for human interventional and preclinical evidence pertaining to the safety and efficacy of green tea for lung cancer. Results: A total of 84 articles met inclusion criteria: two Phase I trials, three reports of one surrogate study, and 79 preclinical studies. There is a lack of controlled trials investigating green tea for lung cancer. Two Phase I studies showed no objective tumor responses at the maximum tolerated dose, ranging from 3 to 4.2 g/m2 green tea extract (GTE) per day. Four cups of green tea daily decreased DNA damage (8OH-dG) in smokers. Human studies indicate that 800mg of green tea catechins daily does not alter activity of the CYP2D6, CYP1A2, CYP3A4 and CYP2C9 enzymes, however in vitro evidence suggests that green tea may bind to and reduce the effectiveness of bortezomib. Green tea applied topically may improve the healing time of radiation burns. Conclusions: Although some evidence suggests that chemopreventative benefits can be accrued from green tea, there is currently insufficient evidence to support green tea as a treatment or preventative agent for lung cancer. Green tea should not be used by patients on bortezomib therapy. Further research is warranted to explore this natural agent for lung cancer treatment and prevention.

Modulation of angiogenesis by dietary phytoconstituents in the prevention and intervention of breast cancer

Breast cancer is the leading cause of cancer-related deaths for women in the United States and the rest of the world. About 8% of women develop breast cancer during the course of their lives. Dietary habits are closely associated with both the risk and progression of breast cancer. Dietary agents have accumulated increasing importance with regards to the prevention and treatment of breast cancer. One such manner by which these compounds can target breast cancer development and progression is through interference with the angiogenic pathways. Angiogenesis is an intricate process that involves the development of new capillaries from previously existing blood vessels. Disruption of this pathway, therefore, provides a novel and effective avenue for therapeutic intervention of breast cancer. Various phytochemicals found in the diet kill breast cancer cells in vitro and prevent as well as suppress breast cancer progression in various preclinical animal models. This review examines the value of dietary phytoconstituents in the prevention and treatment of breast cancer through modulation of the intricate and complex process of angiogenesis. In addition, the potential benefits, challenges, and future directions of research on anti-angiogenic dietary phytochemicals in the prevention and intervention of breast cancer are also addressed.

The effect of overweight and nutrition on prognosis in breast cancer

BACKGROUND

Breast cancer is the most common cancer in women. Body weight and nutrition are known to play an important role in its pathogenesis. The question thus arises whether lifestyle factors might influence the prognosis of breast cancer, potentially offering new approaches for secondary prevention.

METHODS

We selectively searched the Medline database for all studies and meta-analyses on this topic that were published from 1966 to June 2010. We evaluated the cohort studies, interventional trials, and meta-analyses with respect to three target variables: tumor recurrence, tumor-specific mortality, and overall mortality.

RESULTS

A high body-mass index (BMI) at the time of diagnosis of breast cancer is associated with higher overall mortality, as is weight gain at later times. A low-fat diet rich in fruit, vegetables, and fiber seems to be weakly associated with a better prognosis. On other hand, there is no evidence for any benefit from micronutrients, supplements, or antioxidant foods. Alcohol consumption does not affect the outcome in breast cancer. Two intervention trials of reduced fat intake showed no effect on survival, but the target of the intervention was not met in either trial.

CONCLUSION

The intervention trials yielded negative results. Nevertheless, in view of the methodological difficulties in this area of research and the overall life situation of women with breast cancer, the authors recommend a health-promoting lifestyle with avoidance of overweight and a low-fat diet rich in fruit, vegetables, and fiber.

Green tea catechin intervention of reactive oxygen species-mediated ERK pathway activation and chronically induced breast cell carcinogenesis

Long-term exposure to low doses of environmental carcinogens contributes to sporadic human breast cancers. Epidemiologic and experimental studies indicate that green tea catechins (GTCs) may intervene with breast cancer development. We have been developing a chronically induced breast cell carcinogenesis model wherein we repeatedly expose non-cancerous, human breast epithelial MCF10A cells to bioachievable picomolar concentrations of environmental carcinogens, such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (B[a]P), to progressively induce cellular acquisition of cancer-associated properties, as measurable end points. The model is then used as a target to identify non-cytotoxic preventive agents effective in suppression of cellular carcinogenesis. Here, we demonstrate, for the first time, a two-step strategy that initially used end points that were transiently induced by short-term exposure to NNK and B[a]P as targets to detect GTCs capable of blocking the acquisition of cancer-associated properties and subsequently used end points constantly induced by long-term exposure to carcinogens as targets to verify GTCs capable of suppressing carcinogenesis. We detected that short-term exposure to NNK and B[a]P resulted in elevation of reactive oxygen species (ROS), leading to Raf-independent extracellular signal-regulated kinase (ERK) pathway activation and subsequent induction of cell proliferation and DNA damage. These GTCs, at non-cytotoxic levels, were able to suppress chronically induced cellular carcinogenesis by blocking carcinogen-induced ROS elevation, ERK activation, cell proliferation and DNA damage in each exposure cycle. Our model may help accelerate the identification of preventive agents to intervene in carcinogenesis induced by long-term exposure to environmental carcinogens, thereby safely and effectively reducing the health risk of sporadic breast cancer.

Green tea catechin extract in intervention of chronic breast cell carcinogenesis induced by environmental carcinogens

Sporadic breast cancers are mainly attributable to long-term exposure to environmental factors, via a multi-year, multi-step, and multi-path process of tumorigenesis involving cumulative genetic and epigenetic alterations in the chronic carcinogenesis of breast cells from a non-cancerous stage to precancerous and cancerous stages. Epidemiologic and experimental studies have suggested that green tea components may be used as preventive agents for breast cancer control. In our research, we have developed a cellular model that mimics breast cell carcinogenesis chronically induced by cumulative exposures to low doses of environmental carcinogens. In this study, we used our chronic carcinogenesis model as a target system to investigate the activity of green tea catechin extract (GTC) at non-cytotoxic levels in intervention of cellular carcinogenesis induced by cumulative exposures to pico-molar 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (B[a]P). We identified that GTC, at a non-cytotoxic, physiologically achievable concentration of 2.5 µg/mL, was effective in suppressing NNK- and B[a]P-induced cellular carcinogenesis, as measured by reduction of the acquired cancer-associated properties of reduced dependence on growth factors, anchorage-independent growth, increased cell mobility, and acinar-conformational disruption. We also detected that intervention of carcinogen-induced elevation of reactive oxygen species (ROS), increase of cell proliferation, activation of the ERK pathway, DNA damage, and changes in gene expression may account for the mechanisms of GTC's preventive activity. Thus, GTC may be used in dietary and chemoprevention of breast cell carcinogenesis associated with long-term exposure to low doses of environmental carcinogens.

Green tea polyphenols as proteasome inhibitors: implication in chemoprevention

Next to water, tea is the most popular beverage in the world. The most abundant and active compound in green tea is (-)-epigallocatechin-3-gallate (EGCG), which is extensively studied for its cancer-preventive and anti-cancer activities as well as its cellular targets. One potential molecular target of EGCG is the proteasome. While molecular docking and structure-activity relationship (SAR) analysis suggests that the ester carbon of EGCG is important for mediating its proteasome-inhibitory activity, EGCG is very unstable under physiological conditions. Therefore, a series of analogs were synthesized aiming to improve stability and bioavailability of EGCG. Among them, peracetate-protected or the prodrug of EGCG was found to have increased bioavailability, stability, and proteasome-inhibitory activities against various human cancer cells and tumors compared to EGCG, suggesting its potential use for cancer prevention and treatment. Epidemiological studies have indicated that green tea consumption is associated with the reduced risk of cancers, especially associated with the reduced risk of late stage of cancers. This risk reduction may be attributed not only to proteasome inhibition, but also to numerous other intracellular molecules targeted by EGCG that are involved in cell cycle regulation, apoptosis, angiogenesis, and metastasis.

Sustained systemic delivery of green tea polyphenols by polymeric implants significantly diminishes benzo[a]pyrene-induced DNA adducts

The polyphenolics in green tea are believed to be the bioactive components. However, poor bioavailability following ingestion limits their efficacy in vivo. In this study, polyphenon E (poly E), a standardized green tea extract, was administered by sustained-release polycaprolactone implants (two, 2-cm implants; 20% drug load) grafted subcutaneously or via drinking water (0.8% w/v) to female S/D rats. Animals were treated with continuous low dose of benzo[a]pyrene (BP) via subcutaneous polymeric implants (2 cm; 10% load) and euthanized after 1 and 4 weeks. Analysis of lung DNA by (32)P-postlabeling resulted in a statistically significant reduction (50%; p = 0.023) of BP-induced DNA adducts in the implant group; however, only a modest (34%) but statistically insignificant reduction occurred in the drinking water group at 1 week. The implant delivery system also showed significant reduction (35%; p = 0.044) of the known BP diolepoxide-derived DNA adduct after 4 weeks. Notably, the total dose of poly E administered was >100-fold lower in the implant group than the drinking water group (15.7 versus 1,632 mg, respectively). Analysis of selected phase I, phase II, and nucleotide excision repair enzymes at both mRNA and protein levels showed no significant modulation by poly E, suggesting that the reduction in the BP-induced DNA adducts occurred presumably due to known scavenging of the antidiolepoxide of BP by the poly E catechins. In conclusion, our study demonstrated that sustained systemic delivery of poly E significantly reduced BP-induced DNA adducts in spite of its poor bioavailability following oral administration.

The chemopreventive properties and therapeutic modulation of green tea polyphenols in oral squamous cell carcinoma

Chemoprevention is a relatively novel and promising approach for controlling cancer that uses specific natural products or synthetic agents to suppress, reverse, or prevent premalignancy before transformation into invasive cancer. Oral cavity squamous cell carcinoma (OCSCC) represents a large, worldwide health burden with approximately 274,000 cases diagnosed annually worldwide. Smoking and alcohol consumption are major inducers of OCSCC. Recently, the human papilloma virus was also shown to potentially be an etiologic factor. Due to its easily identifiable risk factors and the presence of premalignant regions, oral cancer makes a good candidate for chemoprevention. Green tea is the most widely consumed beverage in the world, and it has received considerable attention because of its abundant, scientifically proven, beneficial effects on human health. In this review, we discuss the role of green tea in oral cancer chemoprevention with regard to the multiple molecular mechanisms proposed in various in vitro, in vivo, and clinical trials.

Urinary polyphenols, glutathione S-transferases copy number variation, and breast cancer risk: results from the Shanghai women's health study

In vitro studies have found that flavanol epigallocatechin (EGC) and flavonols, but not flavanol epicatechin (EC), activate glutathione S-transferases (GSTs), a family of phase II enzymes that detoxify reactive oxygen species, such as catechol estrogen metabolites. This study was designed to investigate prospectively whether urinary excretion of tea polyphenols interacts with GST polymorphisms to influence breast cancer risk. We conducted a study of 352 incident breast cancer cases and 701 individually matched controls nested within the Shanghai Women's Health Study cohort of women aged 40-70 yr at baseline. Liquid chromatography tandem mass spectrometry was used to measure urinary excretion of flavanols and flavonols. Real-time multiplex PCR was used to quantify the copy number variation in the GSTM1 and GSTT1 genes. Urinary excretion of flavonols and flavanols, particularly EGC (P = 0.02), was significantly higher among women null for GSTM1 than those positive for GSTM1. Flavonols and flavanols (EGC in particular) were associated with a reduced risk of breast cancer among those null for GSTM1 and GSTT1, with a P-value of 0.04 for the interaction between EGC and GSTM1 polymorphism. In contrast, among women possessing both GSTM1 and GSTT1, breast cancer risk increased with levels of flavonols, particularly kaempferol. The differential associations between polyphenols and breast cancer risk by GST polymorphisms, if confirmed, may provide a new avenue for the personalized prevention of breast cancer.

Green tea and breast cancer

The identification of modifiable lifestyle factors that could reduce the risk of breast cancer is a research priority. Despite the enormous chemopreventive potential of green tea and compelling evidence from animal studies, its role in breast cancer development in humans is still unclear. Part of the uncertainty is related to the relatively small number of epidemiological studies on green tea and breast cancer and that the overall results from case-control studies and prospective cohort studies are discordant. In addition, the mechanisms by which green tea intake may influence risk of breast cancer in humans remain not well studied. We review the human studies that have evaluated the relationship between green tea intake and four biomarkers (sex steroid hormones, mammographic density, insulin-like growth factor, adiponectin) that are believed to be important in breast cancer development. Results from these biomarker studies are also inconclusive. Limitations of observational studies and areas of further investigations are discussed.