Diabetes, metformin, and breast cancer in postmenopausal women

Metformin and other anti-diabetic medication use and breast cancer incidence in the Nurses' Health Studies

We aimed to examine the association between the use of metformin and other anti-diabetic medications and breast cancer incidence within two large prospective cohort studies. We followed 185,181 women who participated in the Nurses' Health Study (NHS; 1994-2016) and the NHSII (1995-2017), with baseline corresponding to the date metformin was approved for type 2 diabetes (T2D) treatment in the US Information on T2D diagnosis, anti-diabetes medications, and other covariates was self-reported at baseline and repeatedly assessed by follow-up questionnaires every 2 years. Breast cancer cases were self-reported and confirmed by medical record review. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between medication use and breast cancer were estimated using Cox proportional hazards regression models, adjusting for breast cancer risk factors. During 3,324,881 person-years of follow-up, we ascertained 9,192 incident invasive breast cancer cases, of which 451 were among women with T2D. Compared with women without T2D (n = 169,263), neither metformin use (HR = 0.97; 95% CI = 0.81-1.15) nor other anti-diabetic medications use (HR = 1.11; 95% CI = 0.90-1.36) associated with significantly lower breast cancer incidence. Among women with T2D (n = 15,918), compared with metformin never users, metformin ever use was not significantly inversely associated with breast cancer (HR = 0.92; 95% CI = 0.74-1.15). Although we observed that past use of metformin was inversely associated with breast cancer in the T2D population (HR = 0.67; 95% CI = 0.48-0.94), current use (HR = 1.01; 95% CI = 0.80-1.27) and longer duration of metformin use were not associated with breast cancer (each 2-year interval: HR = 1.01; 95% CI = 0.95-1.07). Overall, metformin use was not associated with the risk of developing breast cancer among the overall cohort population or among women with T2D.

New evidence: Metformin unsuitable as routine adjuvant for breast cancer: a drug-target mendelian randomization analysis

PURPOSE

The potential efficacy of metformin in breast cancer (BC) has been hotly discussed but never conclusive. This genetics-based study aimed to evaluate the relationships between metformin targets and BC risk.

METHODS

Metformin targets from DrugBank and genome-wide association study (GWAS) data from IEU OpenGWAS and FinnGen were used to investigate the breast cancer (BC)-metformin causal link with various Mendelian Randomization (MR) methods (e.g., inverse-variance-weighting). The genetic association between type 2 diabetes (T2D) and the drug target of metformin was also analyzed as a positive control. Sensitivity and pleiotropic tests ensured reliability.

RESULTS

The primary targets of metformin are PRKAB1, ETFDH and GPD1L. We found a causal association between PRKAB1 and T2D (odds ratio [OR] 0.959, P = 0.002), but no causal relationship was observed between metformin targets and overall BC risk (PRKAB1: OR 0.990, P = 0.530; ETFDH: OR 0.986, P = 0.592; GPD1L: OR 1.002, P = 0.806). A noteworthy causal relationship was observed between ETFDH and estrogen receptor (ER)-positive BC (OR 0.867, P = 0.018), and between GPD1L and human epidermal growth factor receptor 2 (HER2)-negative BC (OR 0.966, P = 0.040). Other group analyses did not yield positive results.

CONCLUSION

The star target of metformin, PRKAB1, does not exhibit a substantial causal association with the risk of BC. Conversely, metformin, acting as an inhibitor of ETFDH and GPD1L, may potentially elevate the likelihood of developing ER-positive BC and HER2-negative BC. Consequently, it is not advisable to employ metformin as a standard supplementary therapy for BC patients without T2D.

Metformin and Breast Cancer: Current Findings and Future Perspectives from Preclinical and Clinical Studies

Over the last several decades, a growing body of research has investigated the potential to repurpose the anti-diabetic drug metformin for breast cancer prevention and/or treatment. Observational studies in the early 2000s demonstrated that patients with diabetes taking metformin had decreased cancer risk, providing the first evidence supporting the potential role of metformin as an anti-cancer agent. Despite substantial efforts, two decades later, the exact mechanisms and clinical efficacy of metformin for breast cancer remain ambiguous. Here, we have summarized key findings from studies examining the effect of metformin on breast cancer across the translational spectrum including in vitro, in vivo, and human studies. Importantly, we discuss critical factors that may help explain the significant heterogeneity in study outcomes, highlighting how metformin dose, underlying metabolic health, menopausal status, tumor subtype, membrane transporter expression, diet, and other factors may play a role in modulating metformin's anti-cancer effects. We hope that these insights will help with interpreting data from completed studies, improve the design of future studies, and aid in the identification of patient subsets with breast cancer or at high risk for the disease who are most likely to benefit from metformin treatment.

Antidiabetic Drugs in Breast Cancer Patients

Diabetes is one of the leading chronic conditions worldwide, and breast cancer is the most prevalent cancer in women worldwide. The linkage between diabetes and its ability to increase the risk of breast cancer should always be analyzed in patients. This review focuses on the impact of antihyperglycemic therapy in breast cancer patients. Patients with diabetes have a higher risk of developing cancer than the general population. Moreover, diabetes patients have a higher incidence and mortality of breast cancer. In this review, we describe the influence of antidiabetic drugs from insulin and metformin to the current and emerging therapies, incretins and SGLT-2 inhibitors, on breast cancer prognosis. We also emphasize the role of obesity and the metastasis process in breast cancer patients who are treated with antidiabetic drugs.

Diabetes and incidence of breast cancer and its molecular subtypes: A systematic review and meta-analysis

Diabetes mellitus (DM) has been proposed to be positively associated with breast cancer (BCa) risk due to shared risk factors, metabolic dysfunction, and the use of antidiabetic medications. We conducted a systematic review and meta-analysis to evaluate the association between DM and BCa risk. We searched PubMed, Embase, and Web of Science for cohort and case-control studies assessing the association between DM and BCa published before 10 December 2021. Two reviewers independently screened the studies for inclusion, abstracted article data, and rated study quality. Random effects models were used to estimate summary risk ratios (RRs) and 95% confidence intervals (CIs). From 8396 articles identified in the initial search, 70 independent studies were included in the meta-analysis. DM was associated with an overall increased risk of BCa (RR = 1.20, 95% CI: 1.11-1.29). The 24 case-control studies demonstrated a stronger association (RR = 1.26, 95% CI: 1.13-1.40) than the 46 cohort studies (RR = 1.15, 95% CI: 1.05-1.27). Studies reporting risk by menopausal status found that postmenopausal women had an elevated risk of developing BCa (RR = 1.12, 95% CI: 1.07-1.17). No association between DM and BCa risk was observed among premenopausal women (RR = 0.95, 95% CI: 0.85-1.05). In addition, DM was associated with significantly increased risks of oestrogen receptor (ER)+ (RR = 1.09, 95% CI: 1.00-1.20), ER- (RR = 1.16, 95% CI: 1.04-1.30), and triple negative BCa (RR = 1.41, 95% CI: 1.01-1.96). The association estimate for human epidermal growth factor 2-positive BCa was also positive (RR = 1.21, 95% CI: 0.52-2.82), but the CI was wide and crossed the null. Our meta-analysis confirms a modest positive association between DM and BCa risk. In addition, our results suggest that the association between DM and BCa may be modified by menopausal status, and that DM may be differentially associated with BCa subtypes defined by receptor status. Additional studies are warranted to investigate the mechanisms underlying these associations and any influence of DM on BCa receptor expression.

Genetic effect of metformin use on risk of cancers: evidence from Mendelian randomization analysis

BACKGROUND

Increasing number of studies reported the positive effect of metformin on the prevention and treatment of cancers. However, the genetic causal effect of metformin utilization on the risk of common cancers was not completely demonstrated.

METHODS

Two-sample Mendelian Randomization (two-sample MR) analysis was conducted to uncover the genetically predicted causal association between metformin use and 26 kinds of cancers. Besides, two-step Mendelian Randomization (two-step MR) assessment was applied to clarify the mediators which mediated the causal effect of metformin on certain cancer. We utilized five robust analytical methods, in which the inverse variance weighting (IVW) method served as the major one. Sensitivity, pleiotropy, and heterogeneity were assessed. The genetic statistics of exposure, outcomes, and mediators were downloaded from publicly available datasets, including the Open Genome-Wide Association Study (GWAS), FinnGen consortium (FinnGen), and UK Biobank (UKB).

RESULTS

Among 26 kinds of common cancers, HER-positive breast cancer was presented with a significant causal relationship with metformin use [Beta: - 4.0982; OR: 0.0166 (95% CI: 0.0008, 0.3376); P value: 0.0077], which indicated metformin could prevent people from HER-positive breast cancer. Other cancers only showed modest associations with metformin use. Potential mediators were included in two-step MR, among which total testosterone levels (mediating effect: 24.52%) displayed significant mediating roles. Leave-one-out, MR-Egger, and MR-PRESSO analyses produced consistent outcomes.

CONCLUSION

Metformin use exhibited a genetically protective effect on HER-positive breast cancer, which was partially mediated by total testosterone levels.

Diabetes mellitus and risk of breast cancer: a large-scale, prospective, population-based study

BACKGROUND

The objective of this study was to evaluate associations of diabetes overall, type 1 diabetes (T1D), and type 2 diabetes (T2D) with breast cancer (BCa) risk.

METHODS

We included 250,312 women aged 40-69 years between 2006 and 2010 from the UK Biobank cohort. Adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) were calculated for associations of diabetes and its two major types with the time from enrollment to incident BCa.

RESULTS

We identified 8182 BCa cases during a median follow-up of 11.1 years. We found no overall association between diabetes and BCa risk (aHR = 1.02, 95% CI = 0.92-1.14). When accounting for diabetes subtype, women with T1D had a higher risk of BCa than women without diabetes (aHR = 1.52, 95% CI = 1.03-2.23). T2D was not associated with BCa risk overall (aHR = 1.00, 95% CI = 0.90-1.12). However, there was a significantly increased risk of BCa in the short time window after T2D diagnosis.

CONCLUSIONS

Though we did not find an association between diabetes and BCa risk overall, an increased risk of BCa was observed shortly after T2D diagnosis. In addition, our data suggest that women with T1D may have an increased risk of BCa.

Metformin and HER2-positive breast cancer: Mechanisms and therapeutic implications

Due to the strong association between diabetes and cancer incidents, several anti-diabetic drugs, including metformin, have been examined for their anticancer activity. Metformin is a biguanide antihyperglycemic agent used as a first-line drug for type II diabetes mellitus. It exhibits anticancer activity by impacting different molecular pathways, such as AMP-inducible protein kinase (AMPK)-dependent and AMPK-independent pathways. Additionally, Metformin indirectly inhibits IGF-1R signaling, which is highly activated in breast malignancy. On the other hand, breast cancer is one of the major causes of cancer-related morbidity and mortality worldwide, where the human epidermal growth factor receptor-positive (HER2-positive) subtype is one of the most aggressive ones with a high rate of lymph node metastasis. In this review, we summarize the association between diabetes and human cancer, listing recent evidence of metformin's anticancer activity. A special focus is dedicated to HER2-positive breast cancer with regards to the interaction between HER2 and IGF-1R. Then, we discuss combination therapy strategies of metformin and other anti-diabetic drugs in HER2-positive breast cancer.

Metformin Therapy and Breast Cancer Incidence in the Ha'il Region

BACKGROUND

Metformin is a drug used to treat patients with type 2 diabetes, especially those who suffer from obesity. It is also used in the treatment of women with polycystic ovary syndrome (PCOS). This disease is related to insulin resistance and multiplied blood sugar ranges. Furthermore, it has been established that the use of metformin improves the menstrual cycles and ovulation rates of these women.

METHODS

A structured questionnaire was conducted to determine the prevalence of breast cancer among women using metformin in the Ha'il region.

RESULT

The incidence of breast cancer among women using metformin in the Ha'il region is very low. Thus, it can be said that breast cancer cases declined among diabetics taking metformin. This means that metformin use is associated with a lower risk of breast cancer in women with type 2 diabetes, even in cases where these women have a family history of breast cancer.

CONCLUSIONS

According to previous findings, metformin has been linked to lower breast cancer risk in women with type 2 diabetes. Furthermore, the findings of this study corroborate the literature on this subject by indicating that there is a substantial connection between metformin use and a lower risk of breast cancer in women with type 2 diabetes. However, further in vitro and in vivo experiments are crucial to investigate the protective effect of metformin against breast cancer and to confirm our findings.

Dietary Intervention for Preventing Colorectal Cancer: A Practical Guide for Physicians

Colorectal cancer (CRC) is a disease with high prevalence and mortality. Estimated preventability for CRC is approximately 50%, indicating that altering modifiable factors, including diet and body weight, can reduce CRC risk. There is strong evidence that dietary factors including whole grains, high-fiber, red and processed meat, and alcohol can affect the risk of CRC. An alternative strategy for preventing CRC is use of a chemopreventive supplement that provides higher individual exposure to nutrients than what can be obtained from the diet. These include calcium, vitamin D, folate, n-3 polyunsaturated fatty acids, and phytochemicals. Several intervention trials have shown that these dietary chemopreventives have positive protective effects on development and progression CRC. Research on chemoprevention with phytochemicals that possess anti-inflammatory and/or, anti-oxidative properties is still in the preclinical phase. Intentional weight loss by bariatric surgery has not been effective in decreasing long-term CRC risk. Physicians should perform dietary education for patients who are at high risk of cancer for changing their dietary habits and behaviour. An increased understanding of the role of individual nutrients linked to the intestinal micro-environment and stages of carcinogenesis would facilitate the development of the best nutritional formulations for preventing CRC.

Cardiovascular risk factors and breast cancer incidence in a large middle-aged cohort study

BACKGROUND

Several studies have demonstrated that cardiovascular risk factors play a role in the etiology of breast cancer. However, the combined effect of cardiovascular risk factors on the risk of breast cancer is still uncertain.

METHODS

Data from the Atherosclerosis Risk in Communities (ARIC) study, a prospective cohort of middle-aged women, were used to investigate the association of individual and combined cardiovascular risk factors with breast cancer. Cox proportional hazards models were applied to calculate the hazard ratio (HR) and 95% confidence intervals (CI).

RESULTS

A total of 7501 women were included. During a mean follow-up of 19.7 years, 576 women were diagnosed with breast cancer. White women and premenopausal status were independently associated with increased risk of breast cancer. Of the individual cardiovascular risk factors, only obesity was independently associated with an increased risk of breast cancer (HR 1.29, 95% CI 1.04-1.61). Compared with women without cardiovascular risk factors, women having three or greater, but not those with fewer than three cardiovascular risk factors, had a significantly higher risk of developing breast cancer (HR 1.27, 95% CI 1.06-1.53). Subgroup analyses indicated that women with three or greater cardiovascular risk factors had higher risk of breast cancer among postmenopausal Black women, but not among premenopausal Black and White women.

CONCLUSIONS

Combinations of cardiovascular risk factors are associated with increased risk of breast cancer in middle-aged women, especially in postmenopausal Black women. Joint interventions to modify cardiovascular risk factors could be used to prevent breast cancer in these higher-risk individuals.

Metformin and Breast Cancer: Where Are We Now?

Breast cancer is the most prevalent cancer and the leading cause of cancer-related death among women worldwide. Type 2 diabetes–associated metabolic traits such as hyperglycemia, hyperinsulinemia, inflammation, oxidative stress, and obesity are well-known risk factors for breast cancer. The insulin sensitizer metformin, one of the most prescribed oral antidiabetic drugs, has been suggested to function as an antitumoral agent, based on epidemiological and retrospective clinical data as well as preclinical studies showing an antiproliferative effect in cultured breast cancer cells and animal models. These benefits provided a strong rationale to study the effects of metformin in routine clinical care of breast cancer patients. However, the initial enthusiasm was tempered after disappointing results in randomized controlled trials, particularly in the metastatic setting. Here, we revisit the current state of the art of metformin mechanisms of action, critically review past and current metformin-based clinical trials, and briefly discuss future perspectives on how to incorporate metformin into the oncologist’s armamentarium for the prevention and treatment of breast cancer.

A Prospective Cohort Study of Metformin as an Adjuvant Therapy for Infertile Women With Endometrial Complex Hyperplasia/Complex Atypical Hyperplasia and Their Subsequent Assisted Reproductive Technology Outcomes

OBJECTIVE

To investigate the adjuvant efficacy of metformin treatment to achieve pathological complete response (CR) in patients with endometrial complex hyperplasia (CH) and complex atypical hyperplasia (CAH), and secondarily, to evaluate their pregnancy outcomes after following assisted reproductive technology (ART).

STUDY DESIGN

This prospective cohort study analyzed 219 patients diagnosed with infertility and CH/CAH from January 2016 to December 2020. Among these patients, 138 were assigned to the control group (progesterone alone) and 81 were assigned to the study group (progesterone+metformin). After 8/12 weeks of therapy, the treatment responses were assessed by histological examination of curettage specimens obtained by hysteroscopy. Once the pathological results indicated CR, the patients were able to receive ART. The ART treatment and follow-up data of these patients were collected and analyzed.

RESULTS

116 patients in the control group achieved CR, compared with 76 patients in the study group. The CR rate in the control group was significantly lower than that in the study group (P=0.034). We then divided the patients into subgroups to compare the treatment responses. In the subgroup analyses, patients with body mass index (BMI) ≥25 kg/m² and patients with polycystic ovarian syndrome (PCOS) had higher CR rates in the metformin group compared with the control group (P=0.015, P=0.028 respectively). Subsequently, 68 patients in the control group and 47 patients in the study group received an ART cycle. We examined the pregnancy indications and found no significant differences in the clinical pregnancy rate and live birth rate between the two groups (P>0.05).

CONCLUSION

Regression of CH/CAH may be improved by progesterone+metformin compared with progesterone alone. The effect was particularly pronounced in patients with BMI ≥25 kg/m² and patients with PCOS. Metformin had no obvious effect on subsequent ART outcomes. The trial is registered on the publicly accessible website.

CLINICAL TRIAL REGISTRATION

http://www.chictr.org.cn/showproj.aspx?proj=15372, identifier ChiCTR-ONR-16009078.

De novo cholesterol biosynthesis: an additional therapeutic target for the treatment of postmenopausal breast cancer with excessive adipose tissue

The onset and development of breast cancer in postmenopausal women are associated with closely related individual-dependent factors, including weight gain and high levels of circulating androgens. Adipose tissue is the most peripheral site of aromatase enzyme synthesis; therefore, the excessive accumulation of visceral fat results in increased androgens aromatization and estradiol production that provides the microenvironment favorable to tumorigenesis in mammary epithelial cells expressing estrogen receptors (ERs). Moreover, to meet the increased requirement of cholesterol for cell membrane assembly and the production of steroid hormones to sustain their proliferation, ER-positive cells activate de novo cholesterol biosynthesis and subsequent steroidogenesis. Several approaches have been followed to neutralize the de novo cholesterol synthesis, including specific enzyme inhibitors, statins, and, more recently, metformin. Cumulating evidence indicated that inhibiting cholesterol biosynthesis by statins and metformin may be a promising therapeutic strategy to block breast cancer progression. Unlike antiestrogens and aromatase inhibitors (AIs) which compete for binding to ER and inhibit androgens aromatization, respectively, statins block the production of mevalonic acid by inhibiting the activity of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, and metformin hampers the activation of the sterol regulatory element-binding protein 2 (SREBP2) transcription factor, thus inhibiting the synthesis of several enzymes involved in cholesterol biosynthesis. Noteworthy, statins and metformin not only improve the prognosis of overweight patients with ER-positive cancer but also improve the prognosis of patients with triple-negative breast cancer, the aggressive tumor subtype that lacks, at present, specific therapy.

Effects of early medication treatment and metformin use for cancer prevention in diabetes patients: a nationwide sample cohort study using extended landmark-time analysis

OBJECTIVES

This study investigated the effectiveness of early medication treatment and metformin use for cancer prevention in type 2 diabetes patients.

METHODS

Population-based cohort data were used from the Korean National Health Insurance Service-National Sample Cohort database (KNHIS-NSC) for 2002–2013. Patient-specific medication prescription status was defined by the landmark time (LMT; a fixed time after cohort entry), considering both pre- and post-LMT prescriptions to control methodological biases in observational research. The LMT was set to 2 years. Logistic regression analysis with multivariable adjustment was conducted to analyze cancer incidence by patient-specific medication prescription status.

RESULTS

Only 33.4% of the subjects were prescribed medication early (before the LMT) with compliance. Cancer incidence in individuals with early prescription and compliance was 25% lower (odds ratio [OR], 0.75; 95% confidence interval [CI], 0.67 to 0.84) than in those without. As early-prescribed medications, metformin monotherapy and metformin combination therapy were associated with 34% (OR, 0.66; 95% CI, 0.51 to 0.83) and 25% (OR, 0.75; 95% CI, 0.64 to 0.88) lower cancer risk than non-use, respectively. Patients who were prescribed late (post-LMT) but did not comply with the prescription had a 24% (OR, 1.24; 95% CI, 0.97 to 1.58) higher cancer incidence than non-users. Among patients who started monotherapy early without changes throughout the entire follow-up period, those who started on metformin had a 37% (OR, 0.63; 95% CI, 0.41 to 0.99) lower risk of cancer than non-metformin users.

CONCLUSIONS

Doctors must prescribe antidiabetic medication early, and patient compliance is required, regardless of the prescription time, to prevent cancer. Metformin monotherapy or combination therapy is recommended as an early prescription.

Drugs repurposed: An advanced step towards the treatment of breast cancer and associated challenges

Breast cancer (BC) is mostly observed in women and is responsible for huge mortality in women subjects globally. Due to the continued development of drug resistance and other contributing factors, the scientific community needs to look for new alternatives, and drug repurposing is one of the best opportunities. Here we light upon the drug repurposing with a major focus on breast cancer. BC is a division of cancer known as the leading cause of death of 2.3 million women globally, with 685,000 fatalities. This number is steadily rising, necessitating the development of a treatment that can extend survival time. All available treatments for BC are very costly as well as show side effects. This unfulfilled requirement of the anti-cancer drugs ignited an enthusiasm for drug repositioning, which means finding out the anti-cancer use of already marketed drugs for other complications. With the advancement in proteomics, genomics, and computational approaches, the drug repurposing process hastens. So many drugs are repurposed for the BC, including alkylating agents, antimetabolite, anthracyclines, an aromatase inhibitor, mTOR, and many more. The drug resistance in breast cancer is rising, so reviewing how the challenges in breast cancer can be combated with drug repurposing. This paper provides the updated information on all the repurposed drugs candidates for breast cancer with the molecular mechanism responsible for their anti-tumor activity. Additionally, all the challenges that occur during the repurposing of the drugs are discussed.

Natural Products Targeting Cancer Stem Cells for Augmenting Cancer Therapeutics

Cancer stem cells (CSC) have been identified in several types of solid tumors. In some cases, CSC may be the source of all the tumor cells, the cause of the tumor's resistance to chemotherapeutic agents, and the source of metastatic cells. Thus, a combination therapy targeting non-CSC tumor cells as well as specifically targeting CSCs holds the potential to be highly effective. Natural products (NPs) have been a historically rich source of biologically active compounds and are known for their ability to influence multiple signaling pathways simultaneously with negligible side effects. In this review, we discuss the potential of NPs in targeting multiple signaling pathways in CSC and their potential to augment the efficacy of standard cancer therapy. Specifically, we focus on the anti-CSC activities of flavonoids, FDA-approved drugs originating from natural sources. Additionally, we emphasize the potential of NPs in targeting microRNA-mediated signaling, given the roles of microRNA in the maintenance of the CSC phenotype.

Insulin Resistance and Cancer: In Search for a Causal Link

Insulin resistance (IR) is a condition which refers to individuals whose cells and tissues become insensitive to the peptide hormone, insulin. Over the recent years, a wealth of data has made it clear that a synergistic relationship exists between IR, type 2 diabetes mellitus, and cancer. Although the underlying mechanism(s) for this association remain unclear, it is well established that hyperinsulinemia, a hallmark of IR, may play a role in tumorigenesis. On the other hand, IR is strongly associated with visceral adiposity dysfunction and systemic inflammation, two conditions which favor the establishment of a pro-tumorigenic environment. Similarly, epigenetic modifications, such as DNA methylation, histone modifications, and non-coding RNA, in IR states, have been often associated with tumorigenesis in numerous types of human cancer. In addition to these observations, it is also broadly accepted that gut microbiota may play an intriguing role in the development of IR-related diseases, including type 2 diabetes and cancer, whereas potential chemopreventive properties have been attributed to some of the most commonly used antidiabetic medications. Herein we provide a concise overview of the most recent literature in this field and discuss how different but interrelated molecular pathways may impact on tumor development.

The prognostic outcome of 'type 2 diabetes mellitus and breast cancer' association pivots on hypoxia-hyperglycemia axis

Type 2 diabetes mellitus and breast cancer are complex, chronic, heterogeneous, and multi-factorial diseases; with common risk factors including but not limited to diet, obesity, and age. They also share mutually inclusive phenotypic features such as the metabolic deregulations resulting from hyperglycemia, hypoxic conditions and hormonal imbalances. Although, the association between diabetes and cancer has long been speculated; however, the exact molecular nature of this link remains to be fully elucidated. Both the diseases are leading causes of death worldwide and a causal relationship between the two if not addressed, may translate into a major global health concern. Previous studies have hypothesized hyperglycemia, hyperinsulinemia, hormonal imbalances and chronic inflammation, as some of the possible grounds for explaining how diabetes may lead to cancer initiation, yet further research still needs to be done to validate these proposed mechanisms. At the crux of this dilemma, hyperglycemia and hypoxia are two intimately related states involving an intricate level of crosstalk and hypoxia inducible factor 1, at the center of this, plays a key role in mediating an aggressive disease state, particularly in solid tumors such as breast cancer. Subsequently, elucidating the role of HIF1 in establishing the diabetes-breast cancer link on hypoxia-hyperglycemia axis may not only provide an insight into the molecular mechanisms underlying the association but also, illuminate on the prognostic outcome of the therapeutic targeting of HIF1 signaling in diabetic patients with breast cancer or vice versa. Hence, this review highlights the critical role of HIF1 signaling in patients with both T2DM and breast cancer, potentiates its significance as a prognostic marker in comorbid patients, and further discusses the potential prognostic outcome of targeting HIF1, subsequently establishing the pressing need for HIF1 molecular profiling-based patient selection leading to more effective therapeutic strategies emerging from personalized medicine.

Endocrine prevention of breast cancer

Breast cancer (BC) is the most common non-cutaneous malignancy among women worldwide and is a significant cause of morbidity, mortality, and national health care expenditure. Unfortunately, with few exceptions like alcohol consumption, obesity, and physical activity, most BC risk factors are unmodifiable. Antiestrogen endocrine therapy, commonly known as BC chemoprevention, is an effective method of BC prevention. In multiple randomized trials, two selective estrogen receptor modulators - tamoxifen and raloxifene, and two aromatase inhibitors - exemestane and anastrozole have reduced BC incidence by 50%-65% in high-risk women. An estimated 15% of the US women between 35 and 79 years of age may qualify as high risk for BC, yet a small percentage of these women will ever have a formal BC risk assessment or a discussion of endocrine prevention options. The etiology of underutilization of endocrine prevention of BC is multifactorial - infrequent use of BC risk assessment tools in the primary care settings, insufficient knowledge of BC risk assessment tools and antiestrogen agents among primary care providers, concerns of side effects, inadequate time for counseling during primary care visit, and lack of predictive biomarkers may play significant roles. Many small studies incorporating risk assessment tools and decision-making aids showed minimal success in enhancing endocrine prevention. One critical factor for underutilization of endocrine prevention is low uptake of endocrine prevention by high-risk women even when appropriately recommended. Furthermore, adherence to BC endocrine prevention is unsatisfactorily low. Despite the current infrequent usage, endocrine prevention has the potential to reduce the public health burden of BC significantly. Innovative approaches like finding new agents, alternative dosing and schedule of currently available agents, transdermal medication delivery, increased public and professional awareness, and policymakers' commitments may bring the desired changes.

Hyperinsulinemia in Obesity, Inflammation, and Cancer

The relative insufficiency of insulin secretion and/or insulin action causes diabetes. However, obesity and type 2 diabetes mellitus can be associated with an absolute increase in circulating insulin, a state known as hyperinsulinemia. Studies are beginning to elucidate the cause-effect relationships between hyperinsulinemia and numerous consequences of metabolic dysfunctions. Here, we review recent evidence demonstrating that hyperinsulinemia may play a role in inflammation, aging and development of cancers. In this review, we will focus on the consequences and mechanisms of excess insulin production and action, placing recent findings that have challenged dogma in the context of the existing body of literature. Where relevant, we elaborate on the role of specific signal transduction components in the actions of insulin and consequences of chronic hyperinsulinemia. By discussing the involvement of hyperinsulinemia in various metabolic and other chronic diseases, we may identify more effective therapeutics or lifestyle interventions for preventing or treating obesity, diabetes and cancer. We also seek to identify pertinent questions that are ripe for future investigation.

Making sense of associations between type 2 diabetes, metformin, and breast cancer risk

The relationship between type 2 diabetes (T2D), metformin, and breast cancer is complex. T2D may increase risk, but metformin used as first-line treatment of T2D may decrease breast cancer risk. This comment explores efforts to disentangle effects of T2D and metformin use on breast cancer risk in a prospective study.

The Effect of Metformin on Survival Outcomes of Non-Metastatic Breast Cancer Patients with Type 2 Diabetes

BACKGROUND

There are still inconsistencies about the role of metformin on breast cancer. This study was designed to assess metformin's effect on the prognosis of female breast cancer patients with type II diabetes.

METHODS

The present research was carried out as a retrospective cohort study between 2003 and 2014. Breast cancer patients with pre-existing type II diabetes mellitus were included. Overall survival (OS) and relapse-free survival (RFS) were measured as the main endpoints. Kaplan-Meier estimate was used to calculate survival rates.

RESULTS

217 patients were included with a mean age of 53.32±11.10 years. 148 (68.2%) patients were prescribed metformin and 69 (31.8%) took other antidiabetic drugs (non-metformin group). Five-year OS and RFS rates for all patients were 82.5% (95% CI: 76.0%-87.4%) and 71.1% (95% CI: 64.2%-77.0%) respectively. Log-rank test showed that the metformin group had a significant advantage over the non-metformin group in terms of both OS and RFS rates (p.

Metformin and risk of cancer among patients with type 2 diabetes mellitus: A systematic review and meta-analysis

AIM

We carried out this meta-analysis on all published studies to estimate the overall cancer risk of the use of metformin in T2DM patients.

METHODS

We searched the PubMed, Embase and CNKI databases for all articles within a range of published years from 2007 to 2019 on the association between the use of metformin and cancer risk in T2DM patients. The odds ratio (OR) corresponding to the 95% confidence interval (95% CI) was used to assess the association using a random-effect meta-analysis.

RESULTS

Finally, 67 studies met the inclusion criteria for this study, with 10,695,875 T2DM patients and 145,108 cancer cases. Overall, For T2DM patients of ever vs. never metformin users, there was statistical evidence of significantly decreased cancer risk was found to be associated with ever metformin users (OR=0.70, 95% CI=0.65-0.76). Considering T2DM may be a specific and independent risk factor for various forms of cancer, due to its particular metabolic characteristics of glucose intolerance and hyperinsulinemia, we performed a comparison to estimate the effects of metformin on cancer risk with other anti-diabetes medications (ADMs), our results found significantly decreased cancer risk to be associated with the use of metformin (OR=0.80, 95% CI=0.73-0.87).

CONCLUSION

Our meta-analysis indicated that metformin may be a independent protective factor for cancer risk in T2DM patients.

A prospective study of type 2 diabetes, metformin use, and risk of breast cancer

BACKGROUND

Type 2 diabetes (T2D) has been associated with increased breast cancer risk, but commonly prescribed antidiabetic medications such as metformin may reduce risk. Few studies have investigated T2D and medications together in relation to breast cancer.

PATIENTS AND METHODS

Data came from 44 541 Sister Study participants aged 35 to 74 years at enrollment (2003-2009) who satisfied eligibility criteria, followed through 15 September 2017. Information on time-varying, self-reported, physician-diagnosed, prevalent and incident T2D, use of antidiabetic medications, and covariates was obtained from baseline and follow-up questionnaires. Incident breast cancers were confirmed with medical records. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated.

RESULTS

During follow-up (median, 8.6 years), 2678 breast cancers were diagnosed at least 1 year after enrollment. There were 3227 women (7.2%) with prevalent and 2389 (5.3%) with incident T2D, among whom 61% (n = 3386) were ever treated with metformin. There was no overall association between T2D and breast cancer risk (HR 0.99; 95% CI, 0.87-1.13). However, T2D was associated with increased risk of triple-negative breast cancer (HR 1.40; 95% CI, 0.90-2.16). Compared with not having T2D, T2D with metformin use was not associated with overall breast cancer risk (HR 0.98; 95% CI, 0.83-1.15), but it was associated with decreased risk of estrogen receptor (ER)-positive breast cancer (HR 0.86; 95% CI 0.70-1.05) and increased risk of ER-negative (HR 1.25; 95% CI, 0.84-1.88) and triple-negative breast cancer (HR 1.74; 95% CI, 1.06-2.83). The inverse association with ER-positive cancer was stronger for longer duration (≥10 year) metformin use (HR 0.62; 95% CI, 0.38-1.01; P for trend = 0.09). Results were supported by sensitivity analyses.

CONCLUSION

Our findings suggest that associations between T2D and breast cancer may differ by hormone receptor status and that associations between T2D and ER-positive breast cancer may be reduced by long-term metformin use.

Glucose 6-phosphate dehydrogenase inhibition sensitizes melanoma cells to metformin treatment

Most cancer cells exacerbate the pentose phosphate pathway (PPP) to enhance biosynthetic precursors and antioxidant defenses. Metformin, which is used as a first-line oral drug for the treatment of type 2 diabetes, has been proposed to inhibit the malignant progression of different types of cancers. However, metformin has shown poor efficacy as single agent in several clinical trials. Thus, the aim of the present work was to investigate whether the pharmacological inhibition of G6PDH, the first and rate-limiting enzyme of the PPP, by 6-amino nicotinamide (6-AN) potentiates the antitumoral activity of metformin on different human melanoma cell lines. Our results showed that 6-AN has sensitizing properties to metformin cytotoxicity. The combination of metformin and 6-AN decreased glucose consumption and lactate production, altered the mitochondrial potential and redox balance, and thereby blocked melanoma cell progression, directing cells to apoptosis and necrosis. To our knowledge, this is the first study describing the effect of this combination. Future preclinical studies should be performed to reveal the biological relevance of this finding.

Use of metformin and risk of breast and colorectal cancer

BACKGROUND

Diabetes has been associated with increased risk of cancer, including breast cancer and colorectal cancer. Metformin, an oral hypoglycemic drug, but not other anti-diabetic drugs, has been associated with reduced risk of breast and of colon cancers in some, but not in other, studies.

METHODS

Data from two large-scale, population-based, case-control studies of breast and colorectal cancers etiology, conducted in Northern Israel since 1998 were analyzed to evaluate the association between regular use (>3 times) of metformin prior to diagnosis and risk of developing cancer. The multivariate analyses for both cancer sites included age, family history of breast/colorectal cancer, history of diabetes, sports participation, fruits/vegetables consumption, aspirin and statins use, and for breast cancer, also included use of oral contraceptives and postmenopausal hormones and number of pregnancies. Use of metformin and diabetes status were determined based on valid electronic medical records of the participants.

RESULTS

Metformin use prior to diagnosis of cancer was associated with a decrease in risk of both breast cancer (OR = 0.821, 0.726-0.928, p = 0.002) and colorectal cancer (OR = 0.754, 0.623-0.912, p = 0.004). An inverse association was not identified with use of other anti-diabetic medications. Diabetes was found to be associated with risk of colorectal cancer (OR = 1.204, 1.014-1.431, p = 0.034) but not of breast cancer. No dose response by years of use of metformin was found.

CONCLUSION

These analyses of large population-based studies provide evidence of a strong inverse association of metformin with breast and, even more so, with colorectal cancer risk.

A systematic flux analysis approach to identify metabolic vulnerabilities in human breast cancer cell lines

Background

Increased flux through both glycolytic and oxidative metabolic pathways is a hallmark of breast cancer cells and is critical for their growth and survival. As such, targeting this metabolic reprograming has received much attention as a potential treatment approach. However, the heterogeneity of breast cancer cell metabolism, even within classifications, suggests a necessity for an individualised approach to treatment in breast cancer patients.

Methods

The metabolic phenotypes of a diverse panel of human breast cancer cell lines representing the major breast cancer classifications were assessed using real-time metabolic flux analysis. Flux linked to ATP production, pathway reserve capacities and specific macromolecule oxidation rates were quantified. Suspected metabolic vulnerabilities were targeted with specific pathway inhibitors, and relative cell viability was assessed using the crystal violet assay. Measures of AMPK and mTORC1 activity were analysed through immunoblotting.

Results

Breast cancer cells displayed heterogeneous energy requirements and utilisation of non-oxidative and oxidative energy-producing pathways. Quantification of basal glycolytic and oxidative reserve capacities identified cell lines that were highly dependent on individual pathways, while assessment of substrate oxidation relative to total oxidative capacity revealed cell lines that were highly dependent on individual macromolecules. Based on these findings, mild mitochondrial inhibition in ESH-172 cells, including with the anti-diabetic drug metformin, and mild glycolytic inhibition in Hs578T cells reduced relative viability, which did not occur in non-transformed MCF10a cells. The effects on viability were associated with AMPK activation and inhibition of mTORC1 signalling. Hs578T were also found to be highly dependent on glutamine oxidation and inhibition of this process also impacted viability.

Conclusions

Together, these data highlight that systematic flux analysis in breast cancer cells can identify targetable metabolic vulnerabilities, despite heterogeneity in metabolic profiles between individual cancer cell lines.

Metformin: The Answer to Cancer in a Flower? Current Knowledge and Future Prospects of Metformin as an Anti-Cancer Agent in Breast Cancer

Interest has grown in studying the possible use of well-known anti-diabetic drugs as anti-cancer agents individually or in combination with, frequently used, chemotherapeutic agents and/or radiation, owing to the fact that diabetes heightens the risk, incidence, and rapid progression of cancers, including breast cancer, in an individual. In this regard, metformin (1, 1-dimethylbiguanide), well known as 'Glucophage' among diabetics, was reported to be cancer preventive while also being a potent anti-proliferative and anti-cancer agent. While meta-analysis studies reported a lower risk and incidence of breast cancer among diabetic individuals on a metformin treatment regimen, several in vitro, pre-clinical, and clinical studies reported the efficacy of using metformin individually as an anti-cancer/anti-tumor agent or in combination with chemotherapeutic drugs or radiation in the treatment of different forms of breast cancer. However, unanswered questions remain with regards to areas such as cancer treatment specific therapeutic dosing of metformin, specificity to cancer cells at high concentrations, resistance to metformin therapy, efficacy of combinatory therapeutic approaches, post-therapeutic relapse of the disease, and efficacy in cancer prevention in non-diabetic individuals. In the current article, we discuss the biology of metformin and its molecular mechanism of action, the existing cellular, pre-clinical, and clinical studies that have tested the anti-tumor potential of metformin as a potential anti-cancer/anti-tumor agent in breast cancer therapy, and outline the future prospects and directions for a better understanding and re-purposing of metformin as an anti-cancer drug in the treatment of breast cancer.

Comparative Study of Crude and Wine-Processing Corni Fructus on Chemical Composition and Antidiabetic Effects

Wine processing is a specialized technology which involves sautéing crude herbal medicine using Chinese rice wine. Herein, we identified the changes in chemical profiles and antidiabetic effects of Corni Fructus (CF) after wine processing in high-fat diet (HFD) streptozotocin- (STZ-) induced diabetic mice. A novel high-efficiency method for simultaneously quantifying gallic acid, 5-hydroxymethylfurfural, morroniside, loganin, sweroside, and cornuside by UPLC was developed, and validating crude and wine-processing CF was done for the first time. Mice were randomly divided into the following groups and orally given different solutions for 4 weeks: normal group (NC, 0.4% (w/v) CMC-Na), model group (DM, 0.4% (w/v) CMC-Na), crude CF group (CP, 3.87 g/kg), and wine-processing CF group (PP, 3.87 g/kg) followed by HFD and multiple subcutaneous injection of STZ (40 mg/kg) to induce the diabetes model except the NC group. Biochemical indexes (body weight, fasting blood glucose level, lipid level, insulin, and free fatty acid) and other parameters involving liver toxicity were measured with commercial kits and immunohistochemical method. Comparative studies on pharmacology showed that the crude extracts possess higher efficacy on hypoglycemia and hypolipidemia, while wine-processing products exhibit better effects on liver preservation. Our data suggested that wine processing was recommended when CF was used for protecting the liver; however, crude products should be used as antidiabetic drugs.

Relevance of Translation Initiation in Diffuse Glioma Biology and its Therapeutic Potential

Cancer cells are continually exposed to environmental stressors forcing them to adapt their protein production to survive. The translational machinery can be recruited by malignant cells to synthesize proteins required to promote their survival, even in times of high physiological and pathological stress. This phenomenon has been described in several cancers including in gliomas. Abnormal regulation of translation has encouraged the development of new therapeutics targeting the protein synthesis pathway. This approach could be meaningful for glioma given the fact that the median survival following diagnosis of the highest grade of glioma remains short despite current therapy. The identification of new targets for the development of novel therapeutics is therefore needed in order to improve this devastating overall survival rate. This review discusses current literature on translation in gliomas with a focus on the initiation step covering both the cap-dependent and cap-independent modes of initiation. The different translation initiation protagonists will be described in normal conditions and then in gliomas. In addition, their gene expression in gliomas will systematically be examined using two freely available datasets. Finally, we will discuss different pathways regulating translation initiation and current drugs targeting the translational machinery and their potential for the treatment of gliomas.

Phase 1 Study of Erlotinib and Metformin in Metastatic Triple-Negative Breast Cancer

BACKGROUND

Epidermal growth factor receptor (EGFR) is frequently overexpressed in metastatic triple-negative breast cancer (mTNBC). One strategy for overcoming resistance to EGFR inhibition is concomitant inhibition of downstream signaling. The antidiabetic drug metformin inhibits both MAPK and PI3K/mTOR pathway signaling. We evaluated the combination of erlotinib and metformin in a phase 1 study of patients with mTNBC.

PATIENTS AND METHODS

Patients with mTNBC who had received at least one prior line of therapy for metastatic disease were eligible. Erlotinib dose was fixed at 150 mg daily. Metformin dose escalation was planned according to a 3 + 3 design. Dose-limiting toxicities (DLT) were assessed during the first 5 weeks of therapy. The primary objective was to determine the maximum tolerated dose of metformin with fixed-dose erlotinib. Secondary endpoints were response rate, stable disease rate, and progression-free survival.

RESULTS

Eight patients were enrolled. The median number of prior therapies for metastatic disease was 2.5 (range, 1-6). No DLT events were reported during the DLT assessment period. Most adverse events were grade 1/2. Grade 3 diarrhea despite maximum supportive care required dose reduction of metformin in one patient. Grade 3 rash led to study withdrawal in one patient. No grade 4 adverse events were reported. The best observed response was stable disease in 2 patients (25%). Median progression-free survival was 60 days (range, 36-61 days).

CONCLUSION

Erlotinib and metformin were well tolerated in a population of pretreated mTNBC patients but did not demonstrate efficacy in this population.

Relationship between Diabetes and Diabetes Medications and Risk of Different Molecular Subtypes of Breast Cancer

BACKGROUND

Type II diabetes and certain diabetes treatments have been observed to impact breast cancer risk. However, their associations with different breast cancer molecular subtype defined by estrogen receptor (ER)/progesterone receptor (PR)/HER2 status are unclear.

METHODS

We conducted a retrospective multi-center population-based case-case study consisting of 4,557 breast cancer cases to evaluate the impact of type II diabetes and diabetes medications on the risk of different breast cancer molecular subtypes [ER⁺/HER2^-, ER⁺/HER2⁺, triple negative (ER^-/PR^-/HER2^-), and HER2 overexpressing (H2E, ER^-/PR^-/HER2⁺)]. Using ER⁺/HER2^- cases as the reference group, we estimated ORs and corresponding 95% confidence intervals (CI) for each subtype using polytomous logistic regression.

RESULTS

Compared with those without a diabetes history, women with type II diabetes had a 38% (95% CI, 1.01-1.89) increased odds of triple-negative breast cancer (TNBC). Current and longer term recent metformin use (13-24 months of treatment within the 24-month period prior to breast cancer diagnosis) was associated with elevated odds of TNBC (OR = 1.54; 95% CI, 1.07-2.22 and OR = 1.80; 95% CI, 1.13-2.85, respectively).

CONCLUSIONS

The odds of having a triple-negative rather than ER⁺/HER2^- breast cancer is greater for women with type II diabetes, and particularly for those who were users of metformin. This finding is supported by some preclinical data suggesting that diabetes may be more strongly associated with risk of triple-negative disease.

IMPACT

Our study provides novel evidence regarding potential differential effects of type II diabetes and metformin use on risk of different molecular subtypes of breast cancer.

Mammary stem cells and progenitors: targeting the roots of breast cancer for prevention

Breast cancer prevention is daunting, yet not an unsurmountable goal. Mammary stem and progenitors have been proposed as the cells-of-origin in breast cancer. Here, we present the concept of limiting these breast cancer precursors as a risk reduction approach in high-risk women. A wealth of information now exists for phenotypic and functional characterization of mammary stem and progenitor cells in mouse and human. Recent work has also revealed the hormonal regulation of stem/progenitor dynamics as well as intrinsic lineage distinctions between mammary epithelial populations. Leveraging these insights, molecular marker-guided chemoprevention is an achievable reality.

Efficacious dose of metformin for breast cancer therapy is determined by cation transporter expression in tumours

BACKGROUND AND PURPOSE

It has been extensively reported that the leading anti-diabetic drug, metformin, exerts significant anticancer effects. This hydrophilic, cationic drug requires cation transporters for cellular entry where it activates its intracellular target, the AMPK signalling pathway. However, clinical results on metformin therapy (used at antidiabetic doses) for breast cancer are ambiguous. It is likely that the antidiabetic dose is inadequate in patients that have breast tumours with low cation transporter expression, resulting in non-responsiveness to the drug. We postulate that cation transporter expression and metformin dose are key determinants in its antitumour efficacy in breast cancer.

EXPERIMENTAL APPROACH

Antitumour efficacy of metformin was compared between low cation transporter-expressing MCF-7 breast tumours and MCF-7 tumours overexpressing organic cation transporter 3 (OCT3-MCF7). A dose-response relationship of metformin in combination with standard-of-care paclitaxel (for oestrogen receptor-positive MCF-7 breast tumours) or carboplatin (for triple-negative MDA-MB-468 breast tumours) was investigated in xenograft mice.

KEY RESULTS

Metformin had greater efficacy against tumours with higher cation transporter expression, as observed in OCT3-MCF7 versus MCF-7 tumours and MDA-MB-468 versus MCF-7 tumours. In MCF-7 tumours, a threefold higher metformin dose was required to achieve intratumoural exposure that was comparable to exposure in MDA-MB-468 tumours and enhance antitumour efficacy of standard-of-care in MCF-7 tumours versus MDA-MB-468 tumours. Antitumour efficacy correlated with intratumoural AMPK activation and metformin concentration.

CONCLUSIONS AND IMPLICATIONS

An efficacious metformin dose for breast cancer varies among tumour subtypes based on cation transporter expression, which provides a useful guide for dose selection.

Nutraceuticals and "Repurposed" Drugs of Phytochemical Origin in Prevention and Interception of Chronic Degenerative Diseases and Cancer

BACKGROUND

Chronic, degenerative diseases are often characterized by inflammation and aberrant angiogenesis. For these pathologies, including rheumatoid arthritis, cardiovascular and autoimmune diseases, cancer, diabetes, and obesity, current therapies have limited efficacy.

OBJECTIVES

The validation of novel (chemo)preventive and interceptive approaches, and the use of new or repurposed agents, alone or in combination with registered drugs, are urgently required.

RESULTS

Phytochemicals (triterpenoids, flavonoids, retinoids) and their derivatives, nonsteroidal anti-inflammatory drugs (aspirin) as well as biguanides (metformin and phenformin) originally developed from phytochemical backbones, are multi-target agents showing antiangiogenic and anti-anti-inflammatory proprieties. Many of them target AMPK and metabolic pathways such as the mTOR axis. We summarize the beneficial effects of several compounds in conferring protection and supporting therapy, and as a paradigm, we present data on terpenoids & biquanides on beer hop xanthohumol and hydroxytryrosol from olive mill waste waters.

CONCLUSIONS

These molecules could be employed for combinatorial chemoprevention and interception approaches or chemoprevention/therapy regimens for cancer and other chronic complex diseases.

Diabetes and differences in detection of incident invasive breast cancer

Many women diagnosed with breast cancer have chronic conditions such as diabetes that may impact other health behaviors. Our purpose was to determine if breast cancer screening and detection differs among women with and without diabetes. We conducted a cross-sectional analysis of a retrospective cohort of women aged 52-74 years diagnosed with incident stages I-III breast cancer enrolled in an integrated health plan between 1999 and 2014 with linkage to the Surveillance, Epidemiology and End Results registry (n = 2040). Screening data were taken from electronic health records. We used multivariable modified Poisson regression models with robust standard errors to estimate relative risks (RR) and 95% confidence intervals (CI) for outcomes of (i) receipt of screening in the 2 years prior to diagnosis; (ii) symptom-detected breast cancer; and (iii) diagnosis of locally advanced stage III breast cancer. Compared to women without diabetes, women with diabetes were similar with respect to receipt of screening mammography (78% and 77%), symptom-detected breast cancer (46% and 49%), and stage III diagnosis (7% and 7%). In multivariable models adjusting for age and year of diagnosis, race, BMI, Charlson comorbidity score and depression diagnosis no differences were observed in the outcomes by presence of diabetes. Further investigation is warranted to determine how diabetes acts as a mediating factor in adverse breast cancer outcomes.

Virtual screening of novel compounds as potential ER-alpha inhibitors

Majority of breast cancers diagnosed today are estrogen receptor (ER)-positive, however, progesterone receptor-positive (PR-positive) is also responsible for breast cancer. Tumors that are ER/PR-positive are much more likely to respond to hormone therapy than tumors that are ER/PR-negative. Nearly 105 ERa inhibitors from literature when docked resulted in 31 compounds (pyrazolo[1,5-a]pyrimidine analogs and chromen-2-one derivatives) with better binding affinities. The maximum score obtained was -175.282 kcal/mol for compound, [2-(4- Fluoro-phenylamino)-pyridin-3-yl]-{4-[2-phenyl-7- (3, 4, 5-trimethoxy-phenyl)-pyrazolo[1,5-a]pyrimidine-5-carbonyl]-piperazin-1-yl}-methanone. The major H-bond interactions are observed with Thr347. In pursuit to identify novel ERa inhibitory ligands, virtual screening was carried out by docking pyrazole, bipyrazole, thiazole, thiadiazole etc scaffold analogs from literature.34 bipyrazoles from literature revealed Compound 2, ethyl 5-amino-1-(5-amino-3-anilino-4-ethoxycarbonyl-pyrazol-1-yl)-3-anilino-pyrazole-4-carboxylate, with -175.9 kcal/mol binding affinity with the receptor, where a favourable H-bond was formed with Thr347.On the other hand, screening 2035 FDA approved drugs from Drug Bank database resulted in 11 drugs which showed better binding affinities than ERa bound tamoxifen. Consensus scoring using 5 scoring schemes such as Mol Dock score, mcule, SwissDock, Pose&Rank and DSX respectively resulted in better rank-sumsfor Lomitapide, Itraconazole, Cobicistat, Azilsartanmedoxomil, and Zafirlukast.

Metformin reduces prostate cancer risk among men with benign prostatic hyperplasia: A nationwide population-based cohort study

Benign Prostate Hyperplasia (BPH) has been associated with prostate cancer prevalent among men after 50 years of age, however, it is unclear whether the antidiabetic drug, metformin, can reduce prostate cancer for men with BPH. The insurance claims data of men aged 50 years or older, with both type 2 diabetes mellitus (T2DM) and BPH diagnosed from 1997 to 2007 were analyzed. Individuals were followed up for at least 5 years. We identified 2906 and 2906 patients as the metformin cohort and nonmetformin cohort, respectively. The Cox method analysis showed that the metformin cohort had an adjusted hazard ratio (aHR) of 0.69 (95% confidence interval [CI] = 0.49‐0.96, P = 0.0298) for prostate cancer, compared to the nonmetformin cohort after controlling for age, traditional Chinese medicine (TCM) use, prostate specific antigen, and Charlson comorbidity index. Patients using TCM for BPH (per 6 months) also had an aHR of 0.41 (95% CI = 0.24‐0.69; P = 0.0009). In conclusion, both metformin medication and TCM use could be associated with reduced risk of prostate cancer for men with BPH and diabetes.

Association of antidiabetic medication and statins with breast cancer incidence in women with type 2 diabetes

Purpose

To address the possible association between the use of metformin, other forms of antidiabetic medication (ADM) and statins with the incidence of breast cancer in women with type 2 diabetes (T2D).

Methods

Data were collected from a Finnish nationwide diabetes database (FinDM). The study cohort consisted of women diagnosed with T2D in 1996–2011 in Finland. In full-cohort analysis, Poisson regression was used to estimate hazard ratios (HRs) in relation to use of metformin, insulin, other forms of oral ADM and statins. In nested case–control analysis, up to 20 controls were matched for age and duration of diabetes to each case of breast cancer. Conditional logistic regression was used to estimate HRs in relation to medication use and cumulative use of different forms of ADM, and statins.

Results

2300 women were diagnosed with breast cancer during follow-up. No difference in breast cancer incidence was observed between metformin users [HR 1.02, 95% confidence interval (CI) 0.93–1.11] or statin users (HR 0.97, 95% CI 0.89–1.05) compared with non-users. In nested case–control analysis the results were similar. Use of insulin (HR 1.18, 95% CI 1.03–1.36) was associated with a slightly increased incidence of breast cancer.

Conclusions

No evidence of an association between the use of metformin or statins and the incidence of breast cancer in women with T2D was found. Among insulin users, a slightly higher incidence of breast cancer was observed.

Electronic supplementary material

The online version of this article (10.1007/s10549-019-05185-0) contains supplementary material, which is available to authorized users.

High Glucose Represses the Anti-Proliferative and Pro-Apoptotic Effect of Metformin in Triple Negative Breast Cancer Cells

Metformin, the most widely prescribed anti-diabetic drug, is shown to possess anti-cancer potential in treatment of cancers, including breast cancer; decreases breast cancer risk; and improves overall survival. However, reports suggest that higher glucose concentrations may negatively impact the anti-cancer efficacy of metformin. Therefore, we examined the anti-cancer potential of metformin in triple-negative breast cancer cells (TNBCs) exposed to different glucose (25 mM, 5.5 mM and zero glucose/glucose-starved) conditions. Our data indicates that a high glucose (25 mM) concentration (mimicking diabetes) significantly abrogated the effect of metformin on cell proliferation, cell death and cell cycle arrest in addition to loss of efficacy in inhibition of the mTOR pathway, a key metabolic pathway in TNBC cells. The mTOR pathway is activated in TNBCs compared to other subtypes of breast cancer, regulates the synthesis of proteins that are critical for the growth and survival of cancer cells and its activation is correlated to poor outcomes among TNBC patients, while also contributing to metastatic progression and development of resistance to chemotherapy/radiotherapy. Our studies were performed in two different types of TNBCs, MDA-MB-231 cells (mesenchymal stem cell-like (MSL)) and MDA-MB-468 (basal like-1 (BL-1)). Interestingly, lower concentrations of metformin (50, 100, 250, and 500 μM) significantly increased cell proliferation in 25 mM glucose exposed MDA-MB-231 cells, an effect which was not observed in MDA-MB-468 cells, indicating that the effective concentration of metformin when used as anti-cancer drug in TNBCs may have to be determined based on cell type and blood glucose concentration. Our data indicates that metformin treatment was most effective under zero glucose/glucose-starved conditions in MDA-MB-468 with a significant increase in the apoptotic population (62.3 ± 1.5%; p-value < 0.01). Under 5.5 mM glucose conditions in both MDA-MB-231 and MDA-MB-468 cells our data showed reduced viability of 73.56 ± 2.53%; p-value < 0.05 and 70.49 ± 1.68%; p-value < 0.001, respectively, along with a significant increase in apoptotic populations of both cell types. Furthermore, metformin (2 mM) inhibited the mTOR pathway and its downstream components under zero glucose/glucose-starved conditions indicating that using metformin in combination with agents that inhibit the glycolytic pathway should be more beneficial for the treatment of triple-negative breast cancers in diabetic individuals.

Adiposity, history of diabetes, and risk of pancreatic cancer in postmenopausal women

PURPOSE

The purpose of this study was to examine the association of type II diabetes and anthropometric variables with risk of pancreatic cancer among postmenopausal women.

METHODS

Weight, height, waist circumference, and hip circumference were measured by trained personnel, whereas history of diabetes and weight earlier in life were self-reported. Pancreatic cancer was ascertained via central review of medical records by physician adjudicators. After exclusions, 1045 cases of pancreatic cancer were diagnosed among 156,218 women over a median follow-up of approximately 18 years. Cox proportional hazards models were used to estimate the associations of study factors with pancreatic cancer risk.

RESULTS

Diabetes (hazards ratio (HR): 1.30; 95% confidence intervals (95% CI): 1.01-1.66), and in particular, waist circumference, waist-to-hip ratio, and waist-to-height ratio showed positive associations with pancreatic cancer risk (HRs for highest vs. lowest level 1.38; 95% CI: 1.14-1.66, 1.40; 1.17-1.68; and 1.36; 1.13-1.64, respectively). Body mass index at the baseline showed only a borderline positive association with risk (HR: 1.21; 95% CI: 0.97-1.51). Body mass index at age 50 years, but not at ages 18 and 35 years, was also associated with increased pancreatic cancer risk.

CONCLUSIONS

In this study of postmenopausal women, central adiposity and, to a lesser extent, general adiposity and a history of diabetes, were associated with increased pancreatic cancer risk.

Challenges and perspectives in the treatment of diabetes associated breast cancer

Type 2 diabetes mellitus is one of the most common chronic disease worldwide and affects all cross-sections of the society including children, women, youth and adults. Scientific evidence has linked diabetes to higher incidence, accelerated progression and increased aggressiveness of different cancers. Among the different forms of cancer, research has reinforced a link between diabetes and the risk of breast cancer. Some studies have specifically linked diabetes to the highly aggressive, triple negative breast cancers (TNBCs) which do not respond to conventional hormonal/HER2 targeted interventions, have chances of early recurrence, metastasize, tend to be more invasive in nature and develop drug resistance. Commonly used anti-diabetic drugs, such as metformin, have recently gained importance in the treatment of breast cancer due to their proposed anti-cancer properties. Here we discuss the link between diabetes and breast cancer, the metabolic disturbances in diabetes that support the development of breast cancer, the challenges involved and future perspective and directions. We link the three main metabolic disturbances (dyslipidemia, hyperinsulinemia and hyperglycemia) that occur in diabetes to potential aberrant molecular pathways that may lead to the development of an oncogenic phenotype of the breast tissue, thereby leading to acceleration of cell growth, proliferation, migration, inflammation, angiogenesis, EMT and metastasis and inhibition of apoptosis in breast cancer cells. Furthermore, managing diabetes and treating cancer using a combination of anti-diabetic and classical anti-cancer drugs should prove to be more efficient in the treatment diabetes associated cancers.

Chinese herbal products and the reduction of risk of breast cancer among females with type 2 diabetes in Taiwan: A case-control study

Women with type 2 diabetes have a higher risk of developing breast cancer. In Taiwan, traditional Chinese medicine is widely used to treat diabetes; however, its precise influence has not been empirically tested.The objective of the case-control study is to estimate the effect on the risk of breast cancer of using traditional Chinese medicine for women with type 2 diabetes.More than 80% of women with type 2 diabetes have used traditional Chinese medicine. The most commonly prescribed drug was metformin and the herbal formulas were the Di Huang Wan series, including Liu Wei Di Huang Wan, Qi Ju Di Huang Wan, and Zhi Bai Di Huang Wan, followed by Bai Hu Jia Ren Shen Tang and Yu Quan Wan. For the effect of metformin, women who used traditional Chinese medicine including Di Huang series have a lower risk of breast cancer HR: 0.35 (95%CI: 0.23-0.51) in women younger than 55 and HR: 0.54 (95%CI: 0.37-0.79) in women older than 55.The protective effect of the Di Huang Wan series may be due to the synergetic effect of reducing blood glucose or increasing insulin sensitivity and delaying the insulin resistance of cells. The relationship between the Di Huang Wan series and breast cancer of women with type 2 diabetes requires further investigation.

Association of Metformin with Breast Cancer Incidence and Mortality in Patients with Type II Diabetes: A GRADE-Assessed Systematic Review and Meta-analysis

Background: Preclinical data suggest that metformin may reduce breast cancer incidence and improve cancer prognosis. However, the current evidence in observational studies is inconclusive. A systematic review and meta-analysis was conducted to assess the effect of metformin on the incidence of breast cancer and all-cause mortality in patients with type II diabetes (T2D).Methods: A literature search was performed on Medline, EMBASE, and the Cochrane library from inception to November 2016. Outcomes were incidence of breast cancer and all-cause mortality. Risk of bias and overall certainty of evidence was assessed using the Newcastle-Ottawa Scale and Grading of Recommendations Assessment, Development, and Evaluation (GRADE), respectively. Meta-analyses were performed using the most fully adjusted ORs or HRs and 95% confidence intervals (95% CI) as effect measures.Results: A total of 12 observational studies were included for breast cancer incidence and 11 studies for all-cause mortality. No significant association was found between metformin exposure and incidence of breast cancer (OR = 0.93; 95% CI, 0.85-1.03; I² = 35%). A 45% risk reduction was observed for all-cause mortality (HR = 0.55; 95% CI, 0.44-0.70; I² = 81%). Presence of publication bias is strongly suspected for both outcomes using Egger's funnel plots.Conclusions: The use of metformin may improve overall survival in patients with T2D and breast cancer. No effect of metformin on the incidence of breast cancer was observed. Interpretation of results is limited by the observational nature of the studies and resulting biases.Impact: Clinical trials are warranted to determine the role of metformin in breast cancer risk reduction and prognosis. Cancer Epidemiol Biomarkers Prev; 27(6); 627-35. ©2018 AACR.