Association of Metformin Use with Outcomes in Advanced Endometrial Cancer Treated with Chemotherapy

Associations of metformin therapy treatment with endometrial cancer risk and prognosis: A systematic review and meta-analysis

BACKGROUND

Several abstract studies have demonstrated that metformin may be beneficial for preventing and treating endometrial cancer (EC), while the results have been inconsistent and inconclusive. This systematic review and meta-analysis aimed to investigate the association between metformin use and the incidence and mortality of endometrial cancer in diabetic patients.

METHODS

A systematic literature search was performed in Pubmed, EMBASE, Web of Science, Cochrane Library, SinoMed, CNKI, Wanfang Data, and VIP from inception to November 2022. The outcome measures were hazard ratios (HRs) comparing the EC incidence and mortality in patients with type 2 diabetes mellitus (T2DM) on metformin and non-metformin. A random or fixed-effects model was applied for data analysis, and subgroup analysis was performed to look for factors of heterogeneity. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) assessed the evidence's certainty.

RESULTS

Eleven studies reported data on EC incidence. The pooled results suggested that the use of metformin was associated with a significantly higher incidence of EC (HR = 1.17, 95% CI 1.09-1.26, P < 0.0001). Further, seventeen studies were included for survival analysis. The pooled data showed that metformin could significantly decrease all-cause mortality (HR = 0.62, 95% CI 0.52-0.74, P < 0.00001) and endometrial cancer-specific mortality (HR = 0.95, 95% CI 0.90, 1.00, P = 0.03). Finally, we noted that metformin was associated with significantly improving the progression-free survival (PFS) of EC patients with T2DM (HR = 0.55, 95% CI 0.44, 0.68, P < 0.00001).

CONCLUSIONS

This meta-analysis did not prove that metformin was beneficial for preventing EC. However, metformin could reduce their mortality risk and prolong the progression-free survival time of EC patients with T2DM.

Metabolic reprogramming and interventions in endometrial carcinoma

Cancer cells are usually featured by metabolic adaptations that facilitate their growth, invasion, and metastasis. Thus, reprogramming of intracellular energy metabolism is currently one of the hotspots in the field of cancer research. Whereas aerobic glycolysis (known as the Warburg effect) has long been considered a dominant form of energy metabolism in cancer cells, emerging evidence indicates that other metabolic forms, especially oxidative phosphorylation (OXPHOS), may play a critical role at least in some types of cancer. Of note, women with metabolic syndromes (MetS), including obesity, hyperglycemia, dyslipidemia, and hypertension, have an increased risk of developing endometrial carcinoma (EC), suggesting a close link between metabolism and EC. Interestingly, the metabolic preferences vary among EC cell types, particularly cancer stem cells and chemotherapy-resistant cells. Currently, it is commonly accepted that glycolysis is the main energy provider in EC cells, while OXPHOS is reduced or impaired. Moreover, agents specifically targeting the glycolysis and/or OXPHOS pathways can inhibit tumor cell growth and promote chemosensitization. For example, metformin and weight control not only reduce the incidence of EC but also improve the prognosis of EC patients. In this review, we comprehensively overview the current in-depth understanding of the relationship between metabolism and EC and provide up-to-date insights into the development of novel therapies targeting energy metabolism for auxiliary treatment in combination with chemotherapy for EC, especially those resistant to conventional chemotherapy.

Genetic Alterations and Deregulation of Hippo Pathway as a Pathogenetic Mechanism in Bone and Soft Tissue Sarcoma

The Hippo pathway is an evolutionarily conserved modulator of developmental biology with a key role in tissue and organ size regulation under homeostatic conditions. Like other signaling pathways with a significant role in embryonic development, the deregulation of Hippo signaling contributes to oncogenesis. Central to the Hippo pathway is a conserved cascade of adaptor proteins and inhibitory kinases that converge and regulate the activity of the oncoproteins YAP and TAZ, the final transducers of the pathway. Elevated levels and aberrant activation of YAP and TAZ have been described in many cancers. Though most of the studies describe their pervasive activation in epithelial neoplasms, there is increasing evidence pointing out its relevance in mesenchymal malignancies as well. Interestingly, somatic or germline mutations in genes of the Hippo pathway are scarce compared to other signaling pathways that are frequently disrupted in cancer. However, in the case of sarcomas, several examples of genetic alteration of Hippo members, including gene fusions, have been described during the last few years. Here, we review the current knowledge of Hippo pathway implication in sarcoma, describing mechanistic hints recently reported in specific histological entities and how these alterations represent an opportunity for targeted therapy in this heterogeneous group of neoplasm.

Prognostic value of metformin in cancers: An updated meta-analysis based on 80 cohort studies

BACKGROUND

Experiments have shown that metformin can inhibit cancer cell growth, but clinical observations have been inconsistent, so we pooled the currently available data to evaluate the impact of metformin on cancer survival and progression.

METHODS

PubMed, web of science, Embase, and Cochrane databases were searched. Pooled hazard ratios (HRs) were identified using a random-effects model to estimate the strength of the association between metformin and survival and progression in cancer patients.

RESULTS

We incorporated 80 articles published from all databases which satisfied the inclusion criterion. It showed that metformin was associated with better overall survival (hazard ratio [HR] = 0. 81; 95% confidence interval [CI]: [0.77-0.85]) and cancer-specific survival (HR = 0.79; 95% CI: [0.73-0.86]), and metformin was associated with progression-free survival (HR = 0.76; 95% CI: [0.66-0.87]). In patients with diabetes mellitus, the HR of overall survival was 0.79(95% CI: [0.75-0.83]), progression-free survival was 0.72(95% CI: [0.60-0.85]), and the cancer-specific survival was 0.76(95% CI: [0.68-0.86]). It was proposed that metformin can improve the prognosis of cancer patients with diabetes mellitus.

CONCLUSION

Based on cohort studies, metformin therapy has potential survival benefits for patients with malignancy, especially with the greatest benefits seen in breast cancer on overall survival, progression-free survival, and cancer-specific survival. And metformin also showed potential benefits in cancer-specific survival in colorectal and prostate cancer.

Association between baseline body mass index and survival in men with metastatic hormone-sensitive prostate cancer: ECOG-ACRIN CHAARTED E3805

BACKGROUND

E3805 (CHAARTED) is a phase 3 trial demonstrating improved survival for men with metastatic hormone-sensitive prostate cancer (mHSPC) randomized to treatment with docetaxel (D) and androgen-deprivation therapy (ADT) versus ADT alone. We assessed the association of baseline body mass index (BMI) and metformin exposure with quality of life (QOL) and prostate cancer outcomes including survival in patients enrolled in the CHAARTED study.

METHODS

We performed a posthoc exploratory analysis of the CHAARTED trial of men with mHSPC randomized to treatment with ADT with or without D between 2006 and 2012. Cox proportional hazards models and Kruskal-Wallis test were used to evaluate the association between BMI with QOL and prostate cancer outcomes and between metformin exposure and survival.

RESULTS

In 788 of 790 enrolled patients with prospectively recorded baseline BMI and metformin exposure status, lower BMI was not associated with survival, but was associated with high volume disease (p < 0.0001) and poorer baseline QOL on functional assessment of cancer therapy-prostate (p = 0.008). Only 68 patients had prevalent metformin exposure at baseline in the CHAARTED trial. Four groups were identified: ADT + D + metformin (n = 39); ADT + D (n = 357); ADT + metformin (n = 29); and ADT alone (n = 363). Baseline clinicopathologic characteristics were similar between groups. In this small exploratory multivariable analysis, metformin exposure was not associated with survival (hazard ratio: 1.15; 95% confidence interval: 0.81-1.63, p = 0.44).

CONCLUSIONS

There was no link between baseline BMI and survival, but lower baseline BMI was associated with features of greater cancer burden and poorer QOL.

Docetaxel in combination with metformin enhances antitumour efficacy in metastatic breast carcinoma models: a promising cancer targeting based on PEGylated liposomes

OBJECTIVES

Metformin has been shown to kill cancer stem-like cells in genetically various types of breast carcinoma. With the aim to simultaneously eradicate the bulk population of tumour cells and the rare population of cancer stem-like cells in breast cancer tissues, we used the combination chemotherapy of docetaxel (DTX) with metformin (MET). Furthermore, we introduce an active loading method based on ammonium sulphate 250 mM (SA) for encapsulating docetaxel into liposomes.

METHODS

Docetaxel and metformin encapsulated into PEGylated liposomes with two different methods based on remote or passive loading methods, respectively. The size and surface charge of the liposomes were characterized. DTX content in the nanoliposomes was measured by the high-performance liquid chromatography method. The drug release profiles were evaluated in phosphate-buffered dextrose 5% with the pH of 6.5 and 7.4. We examined the antitumour activity of Taxotere (TAX), and liposomal formulation of DTX and MET as a monotherapy or combination therapy. The biodistribution of liposomes was also investigated using 99mTc hexamethyl propylene amine oxime method in BALB/c mice bearing 4T1 breast carcinoma tumours.

KEY FINDINGS

The final formulations were prepared according to the best physicochemical characteristics which were HSPC/mPEG2000-DSPE/Chol (DTX liposomes) and HSPC/DPPG/mPEG2000-DSPE/Chol (MET liposomes), at molar ratios of 85/5/10 and (55/5/5/35), respectively. In vivo experiments showed that when free or liposomal metformin used in combination with liposomal docetaxel, they prolonged median survival time (MST) from 31 in the control group to 46 days, which demonstrates their promising effects on the survival of the 4T1 breast carcinoma mice models. Moreover, combination therapies could significantly increase life span in comparison with phosphate-buffered saline (PBS) and Taxotere groups at the same dose. Furthermore, in the combination therapy study, treatment with DTX liposomes prepared by ammonium sulphate 250 mM buffer alone resulted in similar therapeutic efficacy to combination therapy. The biodistribution study exhibited significant accumulation of DTX liposomes in the tumours due to the Enhanced Permeability and Retention effect.

CONCLUSIONS

This study also showed that metformin-based combinatorial chemotherapies have superior efficacy versus their corresponding monotherapy counterparts at same doses. The findings confirm that liposomes based on ammonium sulphate 250 mM could be as a promising formulation for efficient DTX delivering and cancer targeting and therefore merit further investigations.

Association Between Metformin Use and the Risk, Prognosis of Gynecologic Cancer

Background

For gynecological cancer patients, the beneficial effect of metformin use remains controversial due to inconsistent results of published articles. By conducting a meta-analysis, we aimed to evaluate the effect of metformin in reducing the risk and improving the survival of gynecological cancer among women with diabetes mellitus (DM).

Methods

Articles exploring association between metformin use and the risk, as well as prognosis of gynecologic cancer in DM, were searched in the databases: PubMed, Web of Science, SCOPUS, EMBASE, EBSCO, and PROQUEST. Articles were published before May 2022. All the studies were conducted using STATA 12.0 software.

Results

The meta-analysis showed no significant association between metformin use and risk of gynecologic cancer in DM with a random effects model [odds ratio (ORs)/relative risk (RR) = 0.91, 95% confidence intervals (CI) 0.77 to 1.08, I² = 84.2%, p < 0.001]. Metformin use was associated with reduced overall survival (OS) and progression-free survival (PFS) of gynecologic cancer in DM with random effects models [OS: hazard ratio (HR) = 0.60, 95% CI 0.49–0.74, I² = 55.2%, p = 0.002; PFS: HR = 0.55, 95% CI 0.33–0.91, I² = 69.1%, p = 0.006], whereas no significant association was showed between metformin use and recurrence-free survival (RFS), as well as cancer-specific survival (CSS) of gynecologic cancer in DM with random effects models (RFS: HR = 0.60, 95% CI 0.30–1.18, I² = 73.7%, p = 0.010; CSS: HR = 0.78, 95% CI 0.43–1.41, I² = 72.4%, p = 0.013).

Conclusions

In conclusion, this meta-analysis indicated that metformin may be a useful adjuvant agent for gynecological cancer with DM, especially for patients with ovarian cancer and endometrial cancer.

Metformin attenuates the production and proliferative effects of prolactin induced by medroxyprogesterone acetate during fertility-sparing treatment for endometrial cancer

Background

Progestin is used for fertility-sparing treatment in cases of endometrial cancer (EC). Progestin can induce hyperprolactinemia by increasing pituitary secretion and endometrial decidualization. However, progestin induces prolactin (PRL) secretion, which stimulates cell proliferation and deleteriously affects treatment. To date, the detrimental effect of PRL, the secretion of which is induced by medroxyprogesterone acetate (MPA) during fertility-sparing treatment, has not yet been fully elucidated. Therefore, we aimed to assess the effects of PRL on EC cells during combined treatment with progestin and metformin.

Methods

In total, 71 patients with EC/endometrial atypical hyperplasia who underwent fertility-sparing treatment at our institution from 2009–2019 were enrolled. Serum PRL levels were determined using enzyme immunoassays; mRNA levels in endometrial tissues were determined using quantitative reverse-transcription PCR. To evaluate MPA-induced decidualization, cancer-associated stromal cells were enzymatically released from surgically removed specimens of six patients with EC. To examine PRL-induced cell proliferation, the EC cell lines Ishikawa, HEC1B, and HEC265 were used. In vitro cell proliferation was evaluated using the WST assay; protein levels of signaling molecules were determined using western blotting.

Results

MPA administration significantly increased serum PRL levels at 3 and 6 months and upregulated IGFBP-1 and PRL mRNA expression in tissues at 3 months of fertility-sparing treatment. Metformin significantly reduced MPA-induced IGFBP-1 and PRL mRNA expression during fertility-sparing treatment and significantly inhibited the upregulation of IGFBP-1 and PRL mRNA and PRL levels due to decidualization induced by MPA and cAMP treatment in primary cultured EC stromal cells. In vitro, PRL increased cell proliferation and ERK1/2 phosphorylation levels, whereas metformin attenuated these increases.

Conclusions

MPA upregulated PRL levels in serum and endometrial tissues during fertility-sparing treatment. Metformin co-administration reduced PRL production and attenuated PRL-induced cell-proliferation activity. This study may provide valuable insights on the application of metformin to improve the outcomes of fertility-sparing treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09858-w.

The present status of metformin in fertility-preserving treatment in atypical endometrial hyperplasia and endometrioid endometrial cancer

Progestin therapy is the main fertility-sparing treatment for women with endometrial cancer (EC) and atypical endometrial hyperplasia (AEH). However, still 15-25% of these women failed to achieve complete response (CR) and then lost their fertility after definitive surgery. Metformin has been demonstrated to play an anti-cancer role in multiple cancers including EC. Several studies also suggested metformin had potential benefit in improving the therapeutic outcome of fertility-preserving treatment alongside with progestin. This review has discussed existed evidence regarding the effect of metformin combined with progestin for women with AEH and EC who desire childbearing. Nevertheless, the therapeutic effect of metformin varied in different studies due to the high heterogeneity in the patient's characteristics, the inconsistency in dose and treatment duration of metformin, the combined use of hysteroscopy, the insufficient sample size and underpowered study-design. Therefore, care should be taken when interpreting the current results on this issue. Till now, there is still no strong evidence supporting the use of metformin in fertility-preserving treatment in AEH and EEC patients. Further research is needed to provide high-quality data to validate the role of metformin as adjunctive therapy alongside with progestin to preserve fertility for AEH and EEC patients.

Perspectives of metformin use in endometrial cancer and other gynaecological malignancies

Insulin resistance and hyperinsulinemia play a key role in type 1 endometrial cancer pathogenesis. Most of these cancers develop on a background of overweight or type 2 diabetes mellitus (T2DM). One of the medications widely used in the treatment of T2DM is biguanide derivative, metformin, which exerts promising anticancer properties principally through activation of adenosine monophosphate kinase (AMPK) and inhibition of mammalian target of rapamycin (mTOR) pathways. Many epidemiological studies on diabetic patients show potential preventative role of metformin in endometrial cancer patients, but data regarding its therapeutic role is still limited. So far, most of attention has been paid to the concept of metformin use in fertility sparing treatment of early-stage cancer. Another investigated alternative is its application in patients with primary advanced or recurrent disease. In this review we present the latest data on clinical use of metformin in endometrial cancer patients and potential underlying mechanisms of its activity. Finally, we present some most important clinical information regarding metformin efficacy in other gynaecological malignancies, mainly breast and ovarian cancer.

Low Expression of Stanniocalcin 1 (STC-1) Protein Is Associated With Poor Clinicopathologic Features of Endometrial Cancer

Stanniocalcin-1 (STC-1) is a glycoprotein hormone involved in diverse biological processes, including regulation of calcium phosphate homeostasis, cell proliferation, apoptosis, inflammation, oxidative stress responses, and cancer development. The role of STC-1 in endometrial cancer (EC) is yet to be elucidated. In this study, we investigated the protein expression pattern of STC-1 in a tissue microarray (TMA) cohort of hysterectomy specimens from 832 patients with EC. We then evaluated the prognostic value of STC-1 expression regarding the clinicopathologic features and patients survival over a period of 140 months. Our results revealed that in EC tissue samples, STC-1 is mainly localized in the endometrial epithelium, although some expression was also observed in the stroma. Decreased STC-1 expression was associated with factors relating to a worse prognosis, such as grade 3 endometrioid tumors (p = 0.030), deep myometrial invasion (p = 0.003), lymphovascular space invasion (p = 0.050), and large tumor size (p = 0.001). Moreover, STC-1 expression was decreased in tumors obtained from obese women (p = 0.014) and in women with diabetes mellitus type 2 (DMT2; p = 0.001). Interestingly, the data also showed an association between DNA mismatch repair (MMR) deficiency and weak STC-1 expression, specifically in the endometrial epithelium (p = 0.048). No association was observed between STC-1 expression and disease-specific survival. As STC-1 expression was particularly low in cases with obesity and DMT2 in the TMA cohort, we also evaluated the correlation between metformin use and STC-1 expression in an additional EC cohort that only included women with DMT2 (n = 111). The analysis showed no difference in STC-1 expression in either the epithelium or the stroma in women undergoing metformin therapy compared to metformin non-users. Overall, our data may suggest a favorable role for STC-1 in EC behavior; however, further studies are required to elucidate the detailed mechanism and possible applications to cancer treatment.

Metformin and cancer-specific survival among breast, colorectal, or endometrial cancer patients: A nationwide data linkage study

AIMS

Equivocal results of association between metformin and cancer-specific survival need more investigation. We tested the hypothesis that adherence to the drug had a lower cancer-specific mortality in a homogeneous population (i.e. regular users).

METHODS

The Australian Cancer database was linked to the Pharmaceutical Benefits Scheme data and the National Death Index. Adherence to metformin was calculated by proportion of days covered. Cox regression models with time-varying covariates were used to estimate multivariable-adjusted cause-specific hazard ratios (HRs) and 95% confidence intervals (CI) for the association of adherence to metformin and cancer-specific mortality.

RESULTS

Between 2003 and 2013, three separate cohorts of 6717, 3121, and 1854 female patients were identified with newly diagnosed breast, colorectal, or endometrial cancer. The 1-year adherence was similar at baseline in three cohorts, on average 75%. Each 10% increase in 1-year adherence to metformin reduced cancer-specific mortality among women with breast cancer (adjusted HR = 0.95; 95% CI, 0.93-0.97), colorectal cancer (adjusted HR = 0.94; 95% CI, 0.91-0.96), or endometrial cancer (adjusted HR = 0.95; 95% CI, 0.90-0.99). The inverse associations remained unchanged in most subgroup analyses.

CONCLUSIONS

Among metformin users, adherence to this drug is inversely associated with reduced cancer-specific mortality. If confirmed, metformin could be considered as an adjuvant treatment.

Metformin Dysregulates the Unfolded Protein Response and the WNT/β-Catenin Pathway in Endometrial Cancer Cells through an AMPK-Independent Mechanism

Multiple lines of evidence suggest that metformin, an antidiabetic drug, exerts anti-tumorigenic effects in different types of cancer. Metformin has been reported to affect cancer cells' metabolism and proliferation mainly through the activation of AMP-activated protein kinase (AMPK). Here, we show that metformin inhibits, indeed, endometrial cancer cells' growth and induces apoptosis. More importantly, we report that metformin affects two important pro-survival pathways, such as the Unfolded Protein Response (UPR), following endoplasmic reticulum stress, and the WNT/β-catenin pathway. GRP78, a key protein in the pro-survival arm of the UPR, was indeed downregulated, while GADD153/CHOP, a transcription factor that mediates the pro-apoptotic response of the UPR, was upregulated at both the mRNA and protein level. Furthermore, metformin dramatically inhibited β-catenin mRNA and protein expression. This was paralleled by a reduction in β-catenin transcriptional activity, since metformin inhibited the activity of a TCF/LEF-luciferase promoter. Intriguingly, compound C, a well-known inhibitor of AMPK, was unable to prevent all these effects, suggesting that metformin might inhibit endometrial cancer cells' growth and survival through the modulation of specific branches of the UPR and the inhibition of the Wnt/β-catenin pathway in an AMPK-independent manner. Our findings may provide new insights on the mechanisms of action of metformin and refine the use of this drug in the treatment of endometrial cancer.

Adjuvant effects of chemotherapeutics and Metformin on MFE-319 endometrial carcinoma cell line

We aimed to investigate the cytotoxicity of Metformin, Cisplatin, and Paclitaxel on MFE-319 endometrial carcinoma cell line using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and immunocytochemistry assays. Half maximal inhibitory concentration (IC₅₀) doses of three drugs alone and in the dual combinations were applied to the cells. Immunocytochemical method was performed for the cell survival and for phosphatidylinositol 3-kinase (PI3K), phosphorylated extracellular regulated kinases (pErk)-1/2, Akt-1, phosphorylated Akt (pAkt)-1/2/3 cell growth markers and angiogenic vascular endothelial growth factor (VEGF). Immunoreactivities were evaluated using H-score and analyzed using the one-way analysis of variance (ANOVA) test for statistics. It was found that these drugs caused a decrease in the immunoreactivities of these markers. Particularly, dual combination of Paclitaxel and Cisplatin decreased the immunoreactivities of PI3K, pErk-1/2, Akt-1, and pAkt-1/2/3. Cisplatin and Paclitaxel were more effective than Metformin; on the other hand, Metformin has been shown to enhance the efficacy of these two drugs. In vitro or in vivo further studies are needed to investigate the efficacy of these three drugs via PI3K/Akt signal pathway.

Combination of metformin and RG7388 enhances inhibition of growth and induction of apoptosis of ovarian cancer cells through the PI3K/AKT/mTOR pathway

Ovarian cancer is a gynecological cancer that has the highest mortality rate and is often resistant to conventional treatments. Therefore, development of new therapies is essential. Metformin (MET), which is the priority drug for treatment of type 2 diabetes, has received increasing attention because of its anti-tumor effects. Here, we examined combined anti-tumor effects of MET and RG7388, the only MDM2 (mouse double minute 2 homolog) antagonist that has entered phase III clinical trials, on ovarian cancer cell lines. We examined effects on proliferation by Cell Counting Kit-8 (CCK-8) and colony formation assays, and effects on apoptosis by flow cytometric analysis and Hoechst staining. Western blotting was used to measure protein expression in cells and tissues treated with MET and/or RG7388. Flow cytometry was used to measure reactive oxygen species (ROS). We also examined the effects of MET and/or RG7388 on inhibition of A2780 cell growth in vivo. The combination of MET and RG7388 significantly increased growth inhibition, apoptosis, and ROS of A2780 and SKOV3 cells compared with either agent alone. Additionally, in vitro and in vivo results showed that MET and/or RG7388 inhibited the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway and their combination had a stronger effect. Our findings suggest that the combination of MET and RG7388 enhances growth inhibition and apoptosis induction of ovarian cancer cells through the PI3K/AKT/mTOR pathway and accumulation of intracellular ROS.

Endometrial Cancer as a Metabolic Disease with Dysregulated PI3K Signaling: Shedding Light on Novel Therapeutic Strategies

Endometrial cancer (EC) is one of the most common malignancies of the female reproductive organs. The most characteristic feature of EC is the frequent association with metabolic disorders. However, the components of these disorders that are involved in carcinogenesis remain unclear. Accumulating epidemiological studies have clearly revealed that hyperinsulinemia, which accompanies these disorders, plays central roles in the development of EC via the insulin-phosphoinositide 3 kinase (PI3K) signaling pathway as a metabolic driver. Recent comprehensive genomic analyses showed that over 90% of ECs have genomic alterations in this pathway, resulting in enhanced insulin signaling and production of optimal tumor microenvironments (TMEs). Targeting PI3K signaling is therefore an attractive treatment strategy. Several clinical trials for recurrent or advanced ECs have been attempted using PI3K-serine/threonine kinase (AKT) inhibitors. However, these agents exhibited far lower efficacy than expected, possibly due to activation of alternative pathways that compensate for the PIK3-AKT pathway and allow tumor growth, or due to adaptive mechanisms including the insulin feedback pathway that limits the efficacy of agents. Overcoming these responses with careful management of insulin levels is key to successful treatment. Further interest in specific TMEs via the insulin PI3K-pathway in obese women will provide insight into not only novel therapeutic strategies but also preventive strategies against EC.

The Role of Hyperglycemia in Endometrial Cancer Pathogenesis

Endometrial cancer is one of the most common cancers in women worldwide and its incidence is increasing. Epidemiological evidence shows a strong association between endometrial cancer and obesity, and multiple mechanisms linking obesity and cancer progression have been described. However, it remains unclear which factors are the main drivers of endometrial cancer development. Hyperglycemia and type 2 diabetes mellitus are common co-morbidities of obesity, and there is evidence that hyperglycemia is a risk factor for endometrial cancer independent of obesity. This review aims to explore the association between hyperglycemia and endometrial cancer, and discuss the evidence supporting a role for increased glucose metabolism in endometrial cancer and how this phenotype may contribute to endometrial cancer growth and progression. Finally, the potential role of blood glucose lowering strategies, including drugs and bariatric surgery, for the treatment of this malignancy will be discussed.

Targeting Endometrial Cancer Stem Cell Activity with Metformin Is Inhibited by Patient-Derived Adipocyte-Secreted Factors

Advanced endometrial cancer continues to have a poor prognosis, due to limited treatment options, which may be further adversely impacted by obesity. Endometrial cancer stem cells have been reported to drive metastasis, chemotherapy resistance and disease relapse, but have yet to be fully characterised and no specific targeted therapies have been identified. Here, we describe the phenotype and genotype of aldehyde dehydrogenase high (ALDH^high) and CD133^+ve endometrial cancer stem cells and how adipocyte secreted mediators block the inhibitory effect of metformin on endometrial cancer stem cell activity. Ishikawa and Hec-1a cell lines were used to characterise ALDH^high and CD133^+ve endometrial cancer cells using flow cytometry, functional sphere assays and quantitative-Polymerase Chain Reaction. The comparative effect of metformin on endometrial cancer stem cell activity and bulk tumour cell proliferation was determined using an Aldefluor and cytotoxicity assay. The impact of adipocyte secreted mediators on metformin response was established using patient-derived conditioned media. ALDH^high cells demonstrated greater endometrial cancer stem cell activity than CD133^+ve cells and had increased expression of stem cell and epithelial-mesenchymal transition genes. Treatment with 0.5-1 mM metformin reduced the proportion and activity of both endometrial cancer stem cell populations (p ≤ 0.05), without affecting cell viability. This effect was, however, inhibited by exposure to patient-derived adipocyte conditioned media. These results indicate a selective and specific effect of metformin on endometrial cancer stem cell activity, which is blocked by adipocyte secreted mediators. Future studies of metformin as an adjuvant therapy in endometrial cancer should be adequately powered to investigate the influence of body mass on treatment response.

PRE-surgical Metformin In Uterine Malignancy (PREMIUM): a Multi-Center, Randomized Double-Blind, Placebo-Controlled Phase III Trial

PURPOSE

Endometrioid endometrial cancer is strongly associated with obesity and insulin resistance. Metformin, an insulin sensitizer, reduces endometrial tumor growth in vitro. Presurgical window studies allow rapid in vivo assessment of antitumor activity. Previous window studies found metformin reduced endometrial cancer proliferation but these lacked methodological rigor. PREMIUM measured the anti-proliferative effect of metformin in vivo using a robust window study design.Patients and Methods: A multicenter, double-blind, placebo-controlled trial randomized women with atypical hyperplasia or endometrioid endometrial cancer to receive metformin (850 mg daily for 3 days, and twice daily thereafter) or placebo for 1 to 5 weeks until surgery. The primary outcome was posttreatment IHC expression of Ki-67. Secondary outcomes investigated the effect of metformin on markers of the PI3K-Akt-mTOR and insulin signaling pathways and obesity.

RESULTS

Eighty-eight women received metformin (n = 45) or placebo (n = 43) and completed treatment. There was no overall difference in posttreatment Ki-67 between the metformin and placebo arms, in an ANCOVA analysis adjusting for baseline Ki-67 expression (mean difference -0.57%; 95% CI, -7.57%-6.42%; P = 0.87). Metformin did not affect expression of markers of the PI3K-Akt-mTOR or insulin signaling pathways, and did not result in weight loss.

CONCLUSIONS

Short-term treatment with standard diabetic doses of metformin does not reduce tumor proliferation in women with endometrioid endometrial cancer awaiting hysterectomy. This study does not support a biological effect of metformin in endometrial cancer and casts doubt on its potential application in the primary and adjuvant treatment settings.

Metformin-induced anticancer activities: recent insights

Metformin is a widely used antidiabetic drug, and there is evidence among diabetic patients that metformin is a chemopreventive agent against multiple cancers. There is also evidence in human studies that metformin is a cancer chemotherapeutic agent, and several clinical trials that use metformin alone or in combination with other drugs are ongoing. In vivo and in vitro cancer cell culture studies demonstrate that metformin induces both AMPK-dependent and AMPK-independent genes/pathways that result in inhibition of cancer cell growth and migration and induction of apoptosis. The effects of metformin in cancer cells resemble the patterns observed after treatment with drugs that downregulate specificity protein 1 (Sp1), Sp3 and Sp4 or by knockdown of Sp1, Sp3 and Sp4 by RNA interference. Studies in pancreatic cancer cells clearly demonstrate that metformin decreases expression of Sp1, Sp3, Sp4 and pro-oncogenic Sp-regulated genes, demonstrating that one of the underlying mechanisms of action of metformin as an anticancer agent involves targeting of Sp transcription factors. These observations are consistent with metformin-mediated effects on genes/pathways in many other tumor types.

Effect of metformin on the survival of patients with ALL who express high levels of the ABCB1 drug resistance gene

BACKGROUND

In acute lymphoblastic leukemia (ALL), high ABCB1 gene expression has been associated with treatment resistance, which affects patient prognosis. Many preclinical reports and retrospective population studies have shown an anti-cancer effect of metformin. Therefore, the objective of this study was to assess the effect of metformin on the treatment regimen in patients with ALL who exhibited high levels of ABCB1 gene expression and to determine its impact on overall survival.

METHODS

A total of 102 patients with ALL were recruited; one group (n = 26) received metformin, and the other received chemotherapy (n = 76). Measurement of ABCB1 transcript expression was performed using qRT-PCR prior to treatment initiation. Survival analysis was performed using Kaplan-Meier curves. The impact of both the type of treatment and the level of expression on the response (remission or relapse) was analyzed by calculating the odds ratio.

RESULTS

The survival of patients with high ABCB1 expression was lower than those with low or absent ABCB1 gene expression (p = 0.030). In the individual analysis, we identified a benefit to adding metformin in the group of patients with high ABCB1 gene expression (p = 0.025). In the metformin user group, the drug acted as a protective factor against both therapeutic failure (odds ratio [OR] 0.07, 95% confidence interval [CI] 0.0037-1.53) and early relapse (OR 0.05, 95% CI 0.0028-1.153).

CONCLUSION

The combined use of metformin with chemotherapy is effective in patients with elevated levels of ABCB1 gene expression. Trial registration NCT 03118128: NCT.

Metformin as a Therapeutic Target in Endometrial Cancers

Endometrial cancer is the most common gynecologic malignancy in developed countries. Its increasing incidence is thought to be related in part to the rise of metabolic syndrome, which has been shown to be a risk factor for the development of hyperestrogenic and hyperinsulinemic states. This has consequently lead to an increase in other hormone-responsive cancers as well e.g., breast and ovarian cancer. The correlation between obesity, hyperglycemia, and endometrial cancer has highlighted the important role of metabolism in cancer establishment and persistence. Tumor-mediated reprogramming of the microenvironment and macroenvironment can range from induction of cytokines and growth factors to stimulation of surrounding stromal cells to produce energy-rich catabolites, fueling the growth, and survival of cancer cells. Such mechanisms raise the prospect of the metabolic microenvironment itself as a viable target for treatment of malignancies. Metformin is a biguanide drug that is a first-line treatment for type 2 diabetes that has beneficial effects on various markers of the metabolic syndrome. Many studies suggest that metformin shows potential as an adjuvant treatment for uterine and other cancers. Here, we review the evidence for metformin as a treatment for cancers of the endometrium. We discuss the available clinical data and the molecular mechanisms by which it may exert its effects, with a focus on how it may alter the tumor microenvironment. The pleiotropic effects of metformin on cellular energy production and usage as well as intercellular and hormone-based interactions make it a promising candidate for reprogramming of the cancer ecosystem. This, along with other treatments aimed at targeting tumor metabolic pathways, may lead to novel treatment strategies for endometrial cancer.

Effect of metformin use on the risk and prognosis of endometrial cancer: a systematic review and meta-analysis

BACKGROUND

Previous studies have suggested that metformin may be useful for preventing and treating endometrial cancer (EC), while the results have been inconsistent. This systematic review and meta-analysis aimed to investigate the association between metformin use and risk and prognosis of patients with EC.

METHODS

PubMed, Embase, and the Cochrane Library databases were searched for observational studies evaluating the effect of metformin on EC prevention or treatment. The odds ratio (OR) was used for analyzing risks, and the hazard ratio (HR) was used for analyzing survival outcomes. A random-effects model was used for data analysis.

RESULTS

Seven studies reported data on EC risk. The pooled results suggested that metformin was not significantly associated with a lower risk of EC [OR = 1.05, 95% confidence interval (CI) 0.82-1.35, P = 0.70]. For patients with diabetes, metformin showed no advantage in reducing the EC risk compared with other interventions (OR = 0.99, 95% CI 0.78-1.26, P = 0.95). Further, seven studies were included for survival analysis. The pooled data showed that metformin could significantly improve the overall survival of patients with EC (HR = 0.61, 95% CI 0.48-0.77, P < 0.05) and reduce the risk of EC recurrence (OR = 0.50, 95% CI 0.28-0.92, P < 0.05) Finally, we noted metformin was associated with significantly improving the overall survival of EC patients among diabetes (HR = 0.47; 95%CI 0.33-0.67, P < 0.05).

CONCLUSIONS

This meta-analysis did not prove that metformin was beneficial for preventing EC. However, metformin could prolong the overall survival of patients with EC and reduce their risk of cancer relapse.

The impact of metformin use on survival in prostate cancer: a systematic review and meta-analysis

Background

Metformin has been implicated to reduce the risk of prostate cancer (PCa) beyond its glucose-lowering effect. However, the influence of metformin on prognosis of PCa is often controversial.

Results

A total of 13 cohort studies encompassing 177,490 individuals were included in the meta-analysis. Data on overall survival (OS) and cancer-specific survival (CSS) was extracted from 8 and six studies, respectively. Comparing metformin users with non-metformin users, the pooled hazard ratios (HRs) for OS and CSS were 0.79 (95% confidence interval [CI] 0.63-0.98) and 0.76 (95% CI 0.57-1.02), respectively. Subgroup analyses stratified by baseline charcteristics indicated significant CSS benefits were noted in studies conducted in USA/Canada with prospective, large sample size, multiple-centered study design. Five studies reported the PCa prognosis for recurrence-free survival (RFS) and metformin use was significantly associated with patient RFS (HR 0.74, 95% CI, 0.58-0.95).

Methods

Relevant studies were searched and identified using PubMed, Embase and Cochrane databases from inception through January 2017, which investigated associations between the use of metformin and PCa prognosis. Combined HRs with 95% CI were pooled using a random-effects model. The primary outcomes of interest were OS and CSS.

Conclusions

Our findings provide indication that metformin therapy has a trend to improve survival for patients with PCa. Further prospective, multi-centered, large sample size cohort studies are warranted to determine the true relationship.

Cause-specific mortality in endometrioid endometrial cancer patients with type 2 diabetes using metformin or other types of antidiabetic medication

AIM

To obtain further evidence of the association between metformin or other types of antidiabetic medication (ADM) and mortality from endometrial cancer (EC) and other causes of death in patients with endometrioid EC and type 2 diabetes (T2D).

MATERIALS AND METHODS

A retrospective cohort of women with existing T2D and diagnosed with endometrioid EC from 1998 to 2011, obtained from a nationwide diabetes database (FinDM), were included in the study. Cumulative mortality from EC and that from other causes was described by using the Aalen-Johansen estimator. Cause-specific mortality rates were analyzed by using Cox models, and adjusted hazard ratios (HRs) with 95% confidence intervals (95% CIs) were estimated in relation to the use of different forms of ADM during the three-year period preceding EC diagnosis.

RESULTS

From the FinDM cohort we identified 1215 women diagnosed with endometrioid EC, of whom 19% were metformin users, 12% were users of other types of oral antidiabetic medication, 25% used other types of oral antidiabetic medication plus metformin, 26% used insulin and 14% had no antidiabetic medication. Mortality from EC was not found to be different in women using metformin (HR 0.89, 95% Cl 0.52-1.54) but mortality from other causes was lower (HR 0.52, 95% Cl 0.31-0.88) compared with women using other types of oral ADM.

CONCLUSIONS

Our findings are inconclusive as to the possible effect of metformin on the prognosis of endometrioid EC in women with T2D. However, use of metformin may reduce mortality from other causes.

Metformin use and survival outcomes in endometrial cancer: a systematic review and meta-analysis

Previous studies have evaluated the effects of metformin use on survival outcomes in endometrial cancer, but their results are inconsistent. We conducted a systematic review and meta-analysis to provide a quantitative assessment of the drug's effects based on available evidence. We searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials to identify relevant studies that evaluated the association between metformin use on survival outcomes in endometrial cancer. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated to evaluate the association of metformin use with overall survival and with progression-free survival using a fixed-effects model. A total of nine studies involving 2,016 patients with endometrial cancer were identified. In a meta-analysis of eight studies involving 1,594 individuals, metformin use was associated with significant improvements in overall survival (HR, 0.51; 95% CI, 0.41 to 0.64). Metformin users similarly showed improved progression-free survival in a meta-analysis of two studies involving 632 individuals (HR, 0.63; 95% CI, 0.46 to 0.87). In conclusion, endometrial cancer patients who use metformin show improved overall survival and progression-free survival. Further studies are required to confirm the full potential effects of metformin use on survival outcomes in endometrial cancer.

Metformin and endometrial cancer survival: a quantitative synthesis of observational studies

Metformin has been reported to have anticancer effect and can affect patient survival in several malignancies. However, the results are inconclusive for endometrial cancer. Hence, we conducted a systematic review and meta-analysis to investigate the prognostic role of metformin in patients with endometrial cancer. Studies were identified from Pubmed and Embase database through March 2017. Observational studies reporting hazard ratios (HRs) with 95% confidence intervals (CIs) for overall survival (OS) and progression-free survival (PFS) were selected. Data were abstracted and summarised using random-effects models. From 250 unique citations, we identified ten studies including 6242 patients with nine studies examining OS and five studies examining PFS. Meta-analysis demonstrated that metformin users had better OS (HR, 0.58; 95% CI, 0.45 to 0.76; P = 0.207, I² = 26.6%) and PFS (HR, 0.61; 95% CI, 0.49 to 0.76; P =0.768, I² = 0%) than non-users for endometrial cancer patients. Similar findings were observed using sensitivity analysis adjusted by trim and filled methods (HR, 0.47; 95% CI, 0.37 to 0.58) and subgroup analyses. Based on the current evidence, we find that metformin use is associated with better OS and PFS in patients with endometrial cancer. However, further large-scale prospective studies are needed to establish its validity.

Effects of metformin on endometrial cancer: Systematic review and meta-analysis

BACKGROUND

Endometrial cancer is one of the most common gynecological cancers, which is frequently preceded by atypical endometrial hyperplasia, a premalignant lesion. Metformin, an antidiabetic drug, has emerged as a new adjunctive strategy for different cancer types, including endometrial cancer. This systematic review and meta-analysis aimed to evaluate the effects of metformin in atypical endometrial hyperplasia and endometrial cancer patients.

METHODS

The search was conducted on January 2017 and the articles were collected in Cochrane, LILACS, PubMed, Scopus and Web of Science. A grey literature search was undertaken using Google SCHOLAR, ProQuest and Open Grey. Nineteen studies were included, which contained information about the following outcomes: reversal of atypical endometrial hyperplasia, cellular proliferation biomarkers expression and overall survival in metformin-users compared to non-users.

RESULTS

Metformin was associated with reversion of atypical endometrial hyperplasia to a normal endometrial, and with decreased cell proliferation biomarkers staining, from 51.94% (CI=36.23% to 67.46%) to 34.47% (CI=18.55% to 52.43%). However, there is a high heterogeneity among studies. Metformin-users endometrial cancer patients had a higher overall survival compared to non-metformin users and non-diabetic patients (HR=0.82; CI: 0.70-0.95; p=0.09, I²=40%).

CONCLUSION

Regardless the high heterogeneity of the analyzed studies, the present review suggests that adjunct metformin treatment may assist in the reversal of atypical endometrial hyperplasia to normal endometrial histology, in the reduction of cell proliferation biomarkers implicated in tumor progression, and in the improvement of overall survival in endometrial cancer. Further work on prospective controlled trials designed to address the effects of adjunct metformin on clinical outcomes is necessary for definite conclusions.

Efficacy of metformin for advanced-stage endometrial cancer: A case report

The paradigm of obesity, diabetes mellitus and insulin resistance possibly plays a critical role in the pathogenesis of endometrial cancer (EC). Impaired glucose tolerance and insulin resistance may play a direct or facilitating role in the neoplastic transformation of the endometrium, whereas antidiabetic therapy, particularly with metformin, has been suggested to inhibit EC progression. We herein present the case of a patient with EC who received metformin monotherapy due to complications after undergoing surgery. At 45 months after the introduction of metformin treatment, the patient had no complaints and continued receiving metformin without signs of tumor recurrence. As metformin is widely used among diabetic patients and in ongoing clinical trials in cancer patients, the aforementioned results deserve further clinical investigation.

Systematic review and meta-analysis of the effect of metformin treatment on overall mortality rates in women with endometrial cancer and type 2 diabetes mellitus

BACKGROUND

Obesity, insulin resistance and type 2 diabetes mellitus (T2DM) have been associated with endometrial cancer (EC). In this systematic review and meta-analysis we evaluated the effect of metformin on clinical outcomes in patients with EC and insulin resistance or T2DM.

METHODS

Four research databases were searched for original articles published in all languages up to 30 October 2016. Outcomes of interest were overall mortality (OM), cancer-specific mortality, disease progression, and metastases. We performed a random effect meta-analysis of adjusted effects expressed as hazard ratios (HR); heterogeneity among studies was described with the I² statistic.

RESULTS

Of the 290 retrieved citations, 6 retrospective cohort studies in women with EC (n=4723) met the inclusion criteria, and 8.9% to 23.8% were treated with metformin; OM data was available from 5 studies. In 4 studies of EC patients (n=4132), metformin use was associated with a significant reduction in OM in comparison with not using metformin (adjusted HR [aHR] 0.64, 95% CI 0.45-0.89, p=0.009). In three studies evaluating patients with EC and T2DM (n=2637), metformin use was associated with a significant reduction in OM (aHR 0.50, 95%CI 0.34-0.74, p=0.0006). There was low to moderate heterogeneity of adjusted effects across studies. There was no information about the effect of metformin on cancer-specific mortality, disease progression, or metastases.

CONCLUSIONS

Metformin treatment is associated with a significant reduction in OM irrespective of diabetes status in patients with EC. The survival benefit suggests that diabetes screening and maintenance of good glycemic control may improve outcomes in EC.

Effect of Metformin on Different Non-Diabetes Related Conditions, a Special Focus on Malignant Conditions: Review of Literature

Metformin has been proven to be one of the most safe and effective antihyperglycemic agents. Through more than six decades of metformin use, it became the most studied hypoglycemic agent; through these studies, it showed a marvelous non-glycemic related effect. These effects include modulation of different points of cancer timeline, weight reduction, cardiovascular health, thyroid diseases, polycystic ovaries disease and many other medical conditions. The aim of this review was to assess the effect of metformin on non-diabetes related medical diseases. We have examined the studies published in PubMed and summarized different randomized controlled trials, observational trials and review articles. This review has summarized most of the non-glycemic effects of metformin. Metformin has been solidly shown to be effective in weight control with certain medications, effective in neuroprotection, in endothelial health, in control of anti-HIV agent side effects and many other crucial health jeopardies. The effects in cancer timeline modulation have taken the biggest part, since it was the most studied area outside the diabetes field. Having mentioned all the above privileges, and in addition to the robust evidence in glycemic control, this consolidates the position of metformin as a first line agent in treatment of diabetes and pre-diabetes. Perhaps in the near future, we may see other indications to use metformin in non-diabetes patients.

Metformin Use Is Associated with Reduced Incidence and Improved Survival of Endometrial Cancer: A Meta-Analysis

Studies have suggested that metformin can potentially decrease the incidence of cancer and improve survival outcomes. However, the association between metformin use and the incidence and survival of endometrial cancer (EC) remains controversial. So, a meta-analysis was performed. An electronic search was conducted using PubMed, EMBASE, and Web of Science. The outcome measures were relative risks (RRs) or hazard ratios (HRs) with 95% confidence intervals (CIs) comparing the EC incidence and survival in patients treated with and without metformin. Eleven studies involving 766,926 participants were included in this study. In the pooled analysis of five studies which evaluated the association of metformin use with the incidence of EC, we found that metformin use was associated with a 13% reduction in EC risk among patients with diabetes (RR = 0.87, 95% CI: 0.80–0.95; p = 0.006). In the pooled analysis of six retrospective cohort studies evaluating the effect of metformin on the survival of EC patients, we found that, relative to nonuse, metformin use significantly improved the survival of EC patients (HR = 0.63, 95% CI: 0.45–0.87; p = 0.006). This study showed that metformin use was significantly associated with a decreased incidence of EC in diabetes and a favorable survival outcome of EC patients.

Metformin Targets Central Carbon Metabolism and Reveals Mitochondrial Requirements in Human Cancers

Repurposing metformin for cancer therapy is attractive due to its safety profile, epidemiological evidence, and encouraging data from human clinical trials. Although it is known to systemically affect glucose metabolism in liver, muscle, gut, and other tissues, the molecular determinants that predict a patient response in cancer remain unknown. Here, we carry out an integrative metabolomics analysis of metformin action in ovarian cancer. Metformin accumulated in patient biopsies, and pathways involving nucleotide metabolism, redox, and energy status, all related to mitochondrial metabolism, were affected in treated tumors. Strikingly, a metabolic signature obtained from a patient with an exceptional clinical outcome mirrored that of a responsive animal tumor. Mechanistically, we demonstrate with stable isotope tracing that these metabolic signatures are due to an inability to adapt nutrient utilization in the mitochondria. This analysis provides new insights into mitochondrial metabolism and may lead to more precise indications of metformin in cancer.

The Effect of Metformin Use during Docetaxel Chemotherapy on Prostate Cancer Specific and Overall Survival of Diabetic Patients with Castration Resistant Prostate Cancer

PURPOSE

Docetaxel is the first line chemotherapy currently used to treat patients with symptomatic metastatic castration resistant prostate cancer. Although it provides survival benefits, it is associated with significant side effects. Novel therapeutic options are needed for patients with metastatic castration resistant prostate cancer and an approach is combining docetaxel with chemosensitizing agents. Metformin has been shown to improve the survival of patients with breast, lung and endometrial cancer receiving chemotherapy, and enhance chemotherapeutic efficacy in breast cancer and colon cancer cells. However, to our knowledge the chemosensitizing effect of metformin in prostate cancer has not been explored. Therefore, the hypothesis for our study was that diabetic patients with metastatic castration resistant prostate cancer who were administered metformin during docetaxel chemotherapy would have improved prostate cancer specific and overall survival.

MATERIALS AND METHODS

This retrospective cohort study used data from several Ontario administrative health care databases. Men older than 65 years diagnosed with metastatic castration resistant prostate cancer and treated with docetaxel were stratified into groups based on diabetes status and use of antidiabetic medications. We evaluated the effect of metformin use with docetaxel on prostate cancer specific survival and overall survival using Kaplan-Meier survival curves, the log rank test and multivariate Cox proportional HRs.

RESULTS

Survival curves showed that metformin use with docetaxel did not improve prostate cancer specific survival (p = 0.9562) or overall survival (p = 0.9927). HRs showed no significant effect of metformin use with docetaxel on prostate cancer specific survival (HR = 0.96, p = 0.66) or overall survival (HR = 0.94, p = 0.39).

CONCLUSIONS

Metformin use during docetaxel chemotherapy did not significantly improve prostate cancer specific or overall survival in diabetic patients with metastatic castration resistant prostate cancer. This study indicates that metformin may not be an effective chemosensitizer for metastatic castration resistant prostate cancer.

The prognostic role of metformin in patients with endometrial cancer: a retrospective study

OBJECTIVE

Metformin has recently been discussed to possess anticancer activities and to positively affect the risk of developing cancer. We performed the present study to investigate the association of metformin and survival in patients with endometrial cancer.

STUDY DESIGN

Within the present study we retrospectively reviewed the records of 465 consecutive patients with endometrial cancer. Drug intake of metformin was correlated with clinico-pathological parameters and the patients' survival. Chi-square test, Kruskal Wallis test, the product limit method of Kaplan and Meier, and multivariable Cox regression models were used to assess associations between metformin and clinico-pathological parameters and survival, as appropriate.

RESULTS

Eighty-seven (18.7%) patients suffered from diabetes and of these 46 (52.8%) used metformin at the time of diagnosis. When analysing all patients, metformin did not affect the patients' survival. However, within the subgroup of overweight patients metformin was associated with a prolongation of overall survival (p=0.04). Within this subgroup, diabetic patients who did not use metformin had a 2.3 times higher risk for death (95%CI 1.1-4.7; p=0.02) compared to non-diabetic patients and diabetic patients using metformin. Metformin was not associated with prolonged recurrence-free or cancer-specific survival, irrespective of the patients' body mass index (p=0.08 and p=0.4, respectively).

CONCLUSION

The results of our study might suggest a beneficial effect of metformin on overall survival in overweight diabetic patients with endometrial cancer. However, the question, if metformin can reduce the risk to die from endometrial cancer or improves all cause mortality only still remains open and needs further investigation.