Observational Studies on the Association Between Post-diagnostic Metformin Use and Survival in Ovarian Cancer: A Systematic Review and Meta-Analysis

Pyroptosis in cancer treatment and prevention: the role of natural products and their bioactive compounds

Targeting programmed cell death (PCD) has been emerging as a promising therapeutic strategy in cancer. Pyroptosis, as a type of PCDs, leads to the cleavage of the gasdermin family and the secretion of pro-inflammatory factors. Gasdermin D (GSDMD) and gasdermin E (GSDME) are the two main executors of pyroptosis. Pyroptosis in tumor and immune cells is essential for tumor progression. Natural products, especially Chinese medicinal herb and their bioactive compounds have recently been regarded as anti-tumor agents that regulate cell pyroptosis under different circumstances. Here, we review the underlying mechanisms of natural products that activate pyroptosis in tumor cells and inhibit pyroptosis in immune cells. Pyroptosis activation in tumor cells leads to tumor cell death, yet pyroptosis inhibition in immune cells may prevent tumor occurrence. Elucidation of the signaling pathways involved in pyroptosis contributes to the understanding of the anti-tumor role of natural products and their potential clinical applications. Therefore, we outline a promising strategy for cancer therapy and prevention using natural products via modulation of pyroptosis.

Association between gestational exposure and risk of orofacial clefts: a systematic review and meta-analysis

BACKGROUND

The occurrence of orofacial Clefts (OFCs) is a congenital disease caused by many factors. According to recent studies, air pollution has a strong correlation with the occurrence of OFCs. However, there are still some controversies about the current research results, and there is no relevant research to review the latest results in recent years.

OBJECTIVE

In this paper, the authors conducted a systematic review and meta-analysis to explore the correlation between ambient air pollution and the occurrence of neonatal OFCs deformity.

METHODS

We searched Pubmed, Web of science, and Embase databases from the establishment of the database to May 2023. We included observational studies on the relationship between prenatal exposure to fine particulate matter 2.5 (PM2.5), fine particulate matter 10 (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO) and the risk of cleft lip (CL), cleft palate (CP), cleft lip with or without palate (CL/P). the Newcastle-Ottawa quality assessment scale (NOS) was used to evaluate the quality of the literature. Funnel plot and Egger's regression were used to verify the publication bias. Random effect model or fixed effect model was used to estimate the combined relative risk (RR) and 95% confidence interval (95%CI).

RESULTS

A total of eleven studies were included in this study, including four cohort studies and seven case-control studies, including 22,453 cases of OFCs. Ten studies had low risk of bias and only one study had high risk of bias. Three studies reported that PM2.5 was positively correlated with CL and CP, with a combined RR and 95%CI of 1.287(1.174,1.411) and 1.267 (1.105,1.454). Two studies reported a positive correlation between O3 and CL, with a combined RR and 95%CI of 1.132(1.047,1.225). Two studies reported a positive correlation between PM10 and CL, with a combined RR and 95%CI of 1.108 (1.017,1.206). No association was found between SO2, CO, NO2 exposure during pregnancy and the risk of OFCs.

CONCLUSION

The results of this study showed that there was a significant statistical correlation between exposure to PM10, PM2.5, O3 and the risk of OFCs in the second month of pregnancy. Exposure assessment, research methods and mechanisms need to be further explored.

Efficacy of metformin therapy in patients with cancer: a meta-analysis of 22 randomised controlled trials

BACKGROUND

To investigate whether metformin monotherapy or adjunctive therapy improves the prognosis in patients with any type of cancer compared to non-metformin users (age ≥18).

METHODS

Databases (Medline, Embase, and the Cochrane Central Register of Controlled Trials) and clinical trial registries ( ClinicalTrials.gov ; the World Health Organization International Clinical Trials Registry Platform) were screened for randomized, controlled trials (RCT) reporting at least progression-free survival (PFS) and/or overall survival (OS). Main outcome measures included hazard ratios (HR), and combined HRs and 95% confidence intervals (CI) were calculated using random-effects models.

RESULTS

Of the 8419 records screened, 22 RCTs comprising 5943 participants were included. Pooled HRs were not statistically significant in both PFS (HR 0.97, 95% CI 0.82-1.15, I² = 50%) and OS (HR 0.98, 95% CI 0.86-1.13, I² = 33%) for patients with cancer between the metformin and control groups. Subgroup analyses demonstrated that metformin treatment was associated with a marginally significant improvement in PFS in reproductive system cancers (HR 0.86, 95% CI 0.74-1.00) and a significantly worse PFS in digestive system cancers (HR 1.45, 95% CI 1.03-2.04). The PFS or OS was observed consistently across maintenance dose, diabetes exclusion, median follow-up, risk of bias, and combined antitumoral therapies.

CONCLUSION

Metformin treatment was not associated with cancer-related mortality in adults compared with placebo or no treatment. However, metformin implied beneficial effects in the PFS of the patients with reproductive system cancers but was related to a worse PFS in digestive system cancers.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42022324672.

What Role Does Pyroptosis Play in Cancer?

Background

Pyroptosis has been attracting much attention recently. We have briefly compared its differences and similarities with other programmed deaths and the process of its study. With further exploration of the caspase family, including caspase-1/3/4/5/8/11, new insights into the molecular pathways of action of pyroptosis have been gained. It is also closely related to the development of many cancers, which at the same time provides us with new ideas for the treatment of cancer.

Scope of Review

We describe what is known regarding the impact of pyroptosis on anticancer immunity and give insight into the potential of harnessing pyroptosis as a tool and applying it to novel or existing anticancer strategies.

Major Conclusions

Pyroptosis, a caspase-dependent cell death, causes pore formation, cell swelling, rupture of the plasma membrane, and release of all intracellular contents. The role of pyroptosis in cancer is an extremely complex issue. There is growing evidence that tumor pyroptosis has anti-tumor and pro-tumor roles. It should be discussed in different cancer periods according to the characteristics of cancer occurrence and development. In cancer treatment, pyroptosis provides us with some potential new targets. For the existing drugs, the study of pyroptosis also helps us make better use of existing drugs for anticancer treatment. Immunotherapy is a hot research direction in the field of cancer treatment.

Association between dietary acid load and cancer risk and prognosis: An updated systematic review and meta-analysis of observational studies

Epidemiological studies have suggested that dietary acid load (DAL) might be related to the risk and prognosis of cancer, whereas the evidence is contentious. Several high-quality observational studies have been published following a prior systematic review with only one study included. Consequently, we conducted an updated systematic review and meta-analysis to comprehensively investigate the relationship between DAL and cancer risk and prognosis. A systematic literature search was conducted in the PubMed, Embase, and Web of Science databases from inception to 26 October 2021. Summary relative risks (RRs) with 95% CIs were calculated using a random-effects model. Publication bias, subgroup, meta-regression, and sensitivity analyses were also conducted. Ten observational studies (six cohorts and four case–control studies) with 227,253 participants were included in this systematic review and meta-analysis. The summary RRs revealed a statistically significant associations between DAL and cancer risk (RR = 1.58, 95% CI = 1.23–2.05, I² = 71.9%, n = 7) and prognosis (RR = 1.53, 95% CI = 1.10–2.13, I² = 77.1%, n = 3). No evidence of publication bias was observed in the current analysis. Positive associations were observed in most subgroup analyses stratified by predefined factors, including region, study design, study quality, study population, participants’ gender, age of participants, cancer type, DAL assessment indicator, and adjustment of potential confounding parameters. No evidence of heterogeneity between subgroups was indicated by meta-regression analyses. The high DAL might be associated with an increased risk of cancer, as well as a poor prognosis of cancer. More high-quality prospective studies are warranted to further determine the associations between DAL and risk and prognosis for specific cancers.

Parity and Metabolic Syndrome Risk: A Systematic Review and Meta-Analysis of 15 Observational Studies With 62,095 Women

Background

Epidemiological studies have provided inconsistent evidence of the association between parity and metabolic syndrome (MetS) risk. We conducted this first systematic review and meta-analysis to comprehensively and precisely quantify this topic.

Methods

Comprehensive searches of PubMed, Embase, and the Web of Science databases were conducted to identify observational studies of the association between parity and MetS risk up to 30 January 2022. Study inclusion, data extraction, and quality assessment were checked and reviewed by two investigators independently. Random-effects models were applied to estimate pooled odds ratios (ORs) and 95% CIs. This study has been registered with PROSPERO.

Results

Two high-quality cohorts and thirteen medium-quality cross-sectional studies involving 62,095 women were finally included. Compared with the nulliparous, the pooled OR of MetS for the ever parity was 1.31 (95% CI = 0.91–1.88, I² = 72.6%, n = 3). Compared with the lowest parity number, the pooled OR of MetS for the highest parity number was 1.38 (95% CI = 1.22–1.57, I² = 60.7%, n = 12). For the dose-response analysis, the pooled OR of MetS for each increment of one live birth was 1.12 (95% CI = 1.05–1.19, I² = 78.6%, n = 6). These findings were robust across subgroups and sensitivity analyses. No evidence of heterogeneity between subgroups was indicated by meta-regression analyses.

Conclusion

The findings suggested that parity was associated with an increased risk of MetS. A sufficient number of large prospective cohort studies are required to fully verify our findings.

Systematic Review Registration

[https://www.crd.york.ac.uk/PROSPERO/], identifier [CRD42022307703].

Factors influencing the anticancer effects of metformin on breast cancer outcomes: a systematic review and meta-analysis

INTRODUCTION

Several clinical trials have attempted to find evidence that supports the use of metformin as an anticancer treatment. However, the observed effects on various breast cancer (BC) outcomes have been heterogeneous.

AREAS COVERED

Based on the outcomes of previous clinical trials, this review discusses the patients' characteristics, cancer intrinsic subtypes, cancer stage, and anticancer treatments that may influence the anticancer effect of metformin on BC outcomes. Additionally, the safety and tolerability of metformin addition to various anticancer regimens are reviewed.

EXPERT OPINION

Metformin is a challenging anticancer agent in BC cohorts, besides being safe and well-tolerated at antidiabetic doses. Survival benefits of metformin have been observed in BC patients with: hormone receptor-positive, human epidermal growth factor receptor-2 overexpression, and high insulin like growth factor-1 receptor expression on the tumor surface. Moreover, patients with diabetes receiving metformin experienced better survival outcomes compared to diabetic patients not receiving metformin. Additionally, metformin has anti-proliferative activity in patients with BC who have high insulin resistance and high body mass index. Besides, metformin has been shown to decrease metastatic events, and enhance the level of metabolic- and insulin-related biomarkers associated with carcinogenesis. Finally, most adverse events following metformin treatment were low-grade GIT toxicities.

Metformin Use and Mortality in Women with Ovarian Cancer: An Updated Meta-Analysis

BACKGROUND

Previous observational studies and meta-analysis suggested a possible association between metformin use and reduced mortality in women with ovarian cancer (OC). However, clinical factors that may influence the relationship remain poorly evaluated. We performed an updated meta-analysis to systematically evaluate the above association and to observe the potential influences of study characteristics on the association.

METHODS

Relevant studies reporting the association between metformin use and mortality in women with OC in the multivariate adjusted model were identified by search of electronic databases that included PubMed, Embase, and Web of Science. The random-effects model was adopted to combine the results.

RESULTS

Nine studies including 10030 women with OC were included. Overall, metformin use was independently associated with reduced overall mortality (hazard ratio (HR): 0.72, 95% confidence interval (CI): 0.55-0.93, P=0.01; I ² = 62%). Consistent results were observed for studies comparing metformin users with nondiabetic women and studies comparing metformin users with diabetic women who did not use metformin (P for subgroup analysis = 0.70). Further subgroup analyses showed consistent results in studies with metformin use before or after the diagnosis of OC, with or without adjustment of body mass index (BMI) and with or without adjustment of concurrent medications (P for subgroup analyses all >0.10).

CONCLUSION

Metformin use is associated with reduced mortality in women with OC, which may be independent of the diabetic status of the controls, timing of metformin use, or adjustment of BMI and concurrent medications. Clinical trials are needed to validate the potential benefits of metformin on survival of OC.

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.

Post-Diagnostic Beta Blocker Use and Prognosis of Ovarian Cancer: A Systematic Review and Meta-Analysis of 11 Cohort Studies With 20,274 Patients

Objectives

Previous experimental studies have indicated that exposure to beta blocker provides protective effects against ovarian cancer (OC). However, findings from epidemiologic studies have still been controversial. Therefore, we carried out a meta-analysis to update and quantify the correlation between post-diagnostic beta blocker usage and OC prognosis.

Methods

The meta-analysis had been registered at PROSPEPO. The number of registration is CRD42020188806. A comprehensive search of available literatures in English prior to April 16, 2020, was conducted in PubMed, EMBASE, and the Web of Science databases. Random-effects models were used to calculate overall hazard ratios (HRs) and 95% confidence intervals (CIs). Publication bias assessments, and subgroup, sensitivity, and meta-regression analyses were also performed.

Results

Of the 637 initially identified articles, 11 retrospective cohort studies with 20,274 OC patients were included. The summary HRs did not reveal any statistically significant associations between post-diagnostic beta blocker use and OC prognosis characteristics, such as total mortality (HR = 1.08, 95% CI = 0.92–1.27, I² = 76.5%, n = 9), cancer-specific mortality (HR = 1.22, 95% CI = 0.89–1.67, I² = 88.1%, n=3), and progression-free survival (HR = 0.88, 95% CI = 0.75–1.05, I² = 0, n = 4). No evidence of publication bias was observed in current analysis. In our subgroup analyses, the majority of results were consistent with the main findings. However, several positive correlations were detected in studies with ≥800 cases (HR = 1.20, 95% CI = 1.05–1.37), no immortal time bias (HR = 1.28, 95% CI = 1.10–1.49), and adjustment for comorbidity (HR = 1.20, 95% CI = 1.05–1.37). In the meta-regression analysis, no evidence of heterogeneity was detected in the subgroups according to study characteristics and confounding factors.

Conclusions

Post-diagnostic beta blocker use has no statistical correlation with OC prognosis. More prospective cohort studies are necessary to further verify our results.

Systematic Review Registration

Identifier (CRD42020188806).

Molecular characteristics and tumorigenicity of ascites-derived tumor cells: mitochondrial oxidative phosphorylation as a novel therapy target in ovarian cancer

Ovarian cancer disseminates primarily intraperitoneally. Detached tumor cell aggregates (spheroids) from the primary tumor are regarded as ‘metastatic units’ that exhibit a low sensitivity to classical chemotherapy, probably due to their unique molecular characteristics. We have analyzed the cellular composition of ascites from OvCa patients, using flow cytometry, and studied their behavior in vitro and in vivo. We conclude that ascites‐derived cultured cells from OvCa patients give rise to two subpopulations: adherent cells and non‐adherent cells. Here, we found that the AD population includes mainly CD90⁺ cells with highly proliferative rates in vitro but no tumorigenic potential in vivo, whereas the NAD population contains principally tumor cell spheroids (EpCAM⁺/CD24⁺) with low proliferative potential in vitro. Enriched tumor cell spheroids from the ascites of high‐grade serous OvCA patients, obtained using cell strainers, were highly tumorigenic in vivo and their metastatic spread pattern precisely resembled the tumor dissemination pattern found in the corresponding patients. Comparative transcriptome analyses from ascites‐derived tumor cell spheroids (n = 10) versus tumor samples from different metastatic sites (n = 30) revealed upregulation of genes involved in chemoresistance (TGM1, HSPAs, MT1s), cell adhesion and cell‐barrier integrity (PKP3, CLDNs, PPL), and the oxidative phosphorylation process. Mitochondrial markers (mass and membrane potential) showed a reduced mitochondrial function in tumoroids from tumor tissue compared with ascites‐derived tumor spheroids in flow cytometry analysis. Interestingly, response to OXPHOS inhibition by metformin and IACS010759 in tumor spheroids correlated with the extent of mitochondrial membrane potential measured by fluorescence‐activated cell sorting. Our data contribute to a better understanding of the biology of ovarian cancer spheroids and identify the OXPHOS pathway as new potential treatment option in advanced ovarian cancer.

The Role of Metformin in Ovarian Cancer: Does Metformin Increase Survival in Ovarian Neoplasm?

The role of metformin in ovarian cancer (OC) remains a topic of research and open discussion. Because OC has a high mortality rate for various reasons, finding a solution is vital. Although metformin has demonstrated a high level of evidence in preventing and increasing survival in other cancers, its role in OC is still not proven. This review highlights the function of metformin as an antineoplastic agent in OC and its effect on overall survival, progress-free survival, and recurrence-free survival. We conducted a literature search in the PubMed database using the medical subject heading keywords, ovarian neoplasm and metformin. The search yielded 94 articles, of which 86 remained after including only English language articles. Finally, 50 articles published between 1997 and 2020 were reviewed. We recommend more randomized controlled trials in the future to determine the safety and efficacy of metformin in OC.

Association between prenatal exposure to ambient particulate matter and risk of hypospadias in offspring: A systematic review and meta-analysis

BACKGROUND

Epidemiological studies on whether prenatal exposure to PM_2.5, PM_2.5-10, and PM₁₀ increases the risk of hypospadias are limited and the results are inconsistent.

OBJECTIVES

We conducted this systematic review and meta-analysis to evaluate these associations.

METHODS

Relevant studies were identified by searching the PubMed and Embase databases up to the end of February 2020. Observational studies that investigated the relationships between prenatal exposure to PM₁₀, PM_2.5, and PM_2.5-10 and the risk of hypospadias in offspring were eligible for the review. The risk of bias was evaluated using the Newcastle-Ottawa scale. Random-effects models were used to estimate pooled relative risks (RRs) and 95% confidence intervals (CIs) for the associations.

RESULTS

Nine studies (two cohort and seven case-control studies) with a total of 2806 hypospadias cases were included. Eight studies were at low risk of bias and only one study was at high risk of bias. Five studies reported the association between per interquartile range increase in PM_2.5 exposure within the first trimester and the risk of hypospadias. The pooled RR was 1.17 (95% CI: 1.00, 1.36). Two studies reported the per interquartile range increase in PM_2.5 exposure during 1 month before pregnancy associated with the risk of hypospadias, with a pooled RR of 1.25 (95% CI: 1.03, 1.51). No association was observed between PM_2.5-10 and PM₁₀ exposure during pregnancy and the risk of hypospadias in offspring.

CONCLUSION

This study suggested a modest association between prenatal PM_2.5 exposure during 1 month before pregnancy or within the first trimester and the risk of hypospadias in offspring. Further large-scale cohort studies are required to verify this association.

Recycling the Purpose of Old Drugs to Treat Ovarian Cancer

The main challenge in ovarian cancer treatment is the management of recurrences. Facing this scenario, therapy selection is based on multiple factors to define the best treatment sequence. Target therapies, such as bevacizumab and polymerase (PARP) inhibitors, improved patient survival. However, despite their achievements, ovarian cancer survival remains poor; these therapeutic options are highly costly and can be associated with potential side effects. Recently, it has been shown that the combination of repurposed, conventional, chemotherapeutic drugs could be an alternative, presenting good patient outcomes with few side effects and low costs for healthcare institutions. The main aim of this review is to strengthen the importance of repurposed drugs as therapeutic alternatives, and to propose an in vitro model to assess the therapeutic value. Herein, we compiled the current knowledge on the most promising non-oncological drugs for ovarian cancer treatment, focusing on statins, metformin, bisphosphonates, ivermectin, itraconazole, and ritonavir. We discuss the primary drug use, anticancer mechanisms, and applicability in ovarian cancer. Finally, we propose the use of these therapies to perform drug efficacy tests in ovarian cancer ex vivo cultures. This personalized testing approach could be crucial to validate the existing evidences supporting the use of repurposed drugs for ovarian cancer treatment.

Adherence to Cancer Prevention Guidelines and Endometrial Cancer Risk: Evidence from a Systematic Review and Dose-Response Meta-analysis of Prospective Studies

Purpose

The evidence of adherence to cancer prevention guidelines and endometrial cancer (EC) risk has been limited and controversial. This study summarizes and quantifies the relationship between adherence to cancer prevention guidelines and EC risk.

Materials and Methods

The online databases PubMed, Web of Science, and EMBASE were searched for relevant publications up to June 2, 2020. This study had been registered at PROSPERO. The registration number is CRD42020149966. Study quality evaluation was performed based on the Newcastle-Ottawa Scale. The I² statistic was used to estimate heterogeneity among studies. Egger’s and Begg’s tests assessed potential publication bias. Summary hazard ratios (HRs) and 95% confidence intervals (CIs) for the relationship between adherence to cancer prevention guidelines score was assigned to participants by summarizing individual scores for each lifestyle-related factor. The scores ranged from least healthy (0) to most healthy (20) and the EC risk was calculated using a random-effects model.

Results

Five prospective studies (four cohort studies and one case-cohort study) consisted of 4,470 EC cases, where 597,047 participants were included. Four studies had a low bias risk and one study had a high bias risk. Summary EC HR for the highest vs. lowest score of adherence to cancer prevention guidelines was 0.54 (95% CI, 0.40 to 0.73) and had a high heterogeneity (I²=86.1%). For the dose-response analysis, an increment of 1 significantly reduced the risk of EC by 6%. No significant publication bias was detected.

Conclusion

This study suggested that adherence to cancer prevention guidelines was negatively related to EC risk.

Glucose promotes epithelial-mesenchymal transitions in bladder cancer by regulating the functions of YAP1 and TAZ

Glucose levels and type 2 diabetes (T2D) are both associated with tumorigenesis and epithelial‐mesenchymal transitions (EMTs). EMTs facilitate bladder cancer (BC) metastasis development, but the mechanism by which high‐glucose levels promote these EMTs in BC remains unclear. Therefore, we sought to elucidate the mechanism underlying EMT promotion due to increased glucose levels. T24 and UMUC‐3 cells were cultured in media containing different glucose concentrations. YAP1, TAZ, GLUT1 and EMT‐associated marker expression was analysed via Western blotting and qPCR. BC cell proliferation and invasion were assessed using MTT and Transwell assays, respectively. A xenograft nude mouse model of diabetes was used to evaluate tumour growth and metastasis in vivo. T2D was positively associated with pathologic grade (P = .016) and TNM stage (P < .001) in BC. High glucose triggered BC cell proliferation and invasion in both in vitro and in vivo conditions. High‐glucose levels also promoted EMTs in BC cells and increased YAP1 and TAZ expression. YAP1 or TAZ knockdown altered EMT marker expression and decreased GLUT1 expression. Overall, our results suggest that high‐glucose levels promote EMTs in BC cells via YAP1 and TAZ regulation. These effector molecules may be promising therapeutic targets for BC cases comorbid with T2D.

The effect of metformin on lung cancer risk and survival in patients with type 2 diabetes mellitus: A meta-analysis

WHAT IS KNOWN AND OBJECTIVE

Metformin has received increasing attention owing to its potential protective effect against cancer. We aimed to summarize evidence regarding the association between metformin and the risk or survival in lung cancer patients with type 2 diabetes.

METHODS

We selected observational studies examining the association between exposure to metformin and the risk or survival in lung cancer. Available publications were searched in PubMed, Cochrane Library, ScienceDirect, Wiley and SpringerLink databases. Meta-analysis was performed with hazard ratios (HRs) and 95% confidence intervals (95% CIs) as effect measures for risk or survival in lung cancer.

RESULTS

Eighteen studies (eight on lung cancer risk and ten on lung cancer survival) were included. Metformin treatment was associated with decreased lung cancer incidence (HR 0.78; 95% CI 0.70-0.86) and increased lung cancer survival (HR 0.65; 95% CI 0.55-0.77). In the subgroup analysis by ethnicity, a significant protective effect of metformin use on lung cancer risk was observed among Asian patients (HR 0.66; 95% CI 0.56-0.76), but not in European patients. On the other hand, the protective effect of metformin use on lung cancer survival was observed in both Asian (HR 0.57; 95% CI 0.49-0.66) and non-Asian (HR 0.79; 95% CI 0.71-0.88) patients. In the subgroup analysis by histology, a protective effect of metformin on lung cancer survival was observed in both non-small-cell lung cancer (HR 0.68; 95% CI 0.54-0.84) and small-cell lung cancer (HR 0.52; 95% CI 0.39-0.69). Funnel plot showed that no significant publication bias existed.

CONCLUSIONS

Our findings demonstrate that metformin is significantly associated with a decreased risk and increased survival in lung cancer.

Infertility and ovarian cancer risk: Evidence from nine prospective cohort studies

Epidemiological studies have investigated the relationship between infertility and the risk of ovarian cancer (OC); however, the results have been inconsistent. We therefore conducted the first meta-analysis to update and quantify the aforementioned association based on prospective cohort studies. Studies were identified by searching PubMed, EMBASE and Web of Science databases up to January 8, 2020. We extracted data from the studies and performed quality assessments. Summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated using a random-effects model. Publication bias, and subgroup, meta-regression and sensitivity analyses were also conducted. Nine prospective cohort studies with a total of 10 383 OC cases and 6 278 830 participants were included in the present study. The summary RR of the association between infertility and the risk of OC was 1.51 (95% CI: 1.35-1.69), with low heterogeneity. Positive associations were observed in most subgroup analyses stratified by predefined factors, including region, duration of follow-up, study quality, causes of infertility, invasiveness of OC, infertility treatment status and adjustment of potential confounding parameters. No significant publication bias was detected. Our findings suggest that infertility in women were associated with an increased risk of OC.

Mechanism and regulation of pyroptosis-mediated in cancer cell death

Pyroptosis, a form of programmed cell death, has garnered increasing attention as it relates to innate immunity and diseases. The discovery of caspase-1/3/4/5/8/11 function in sensing various challenges expands the spectrum of pyroptosis mediators and also reveals that pyroptosis is not cell type specific. Recent studies have identified that pyroptosis has become a new topic in cancer research because it may affect all stages of carcinogenesis. In this mini-review, we provided a primer on pyroptosis, discussed the induction of pyroptosis in cancer and its implications in cancer management. Moreover, its two important executioners, the gasdermin D (GSDMD) and gasdermin E (GSDME), the functions and mechanisms of them involved in the regulation of cancer therapy were focused on. Small molecules-mediated pyroptosis were found to effectively inhibit various tumor cells. In brief, the findings of pyroptosis-dependent cancer progression, new drugs and therapeutic targets may lead to a promising, novel therapeutic approach for cancer patients.

No Effect of Metformin on Ovarian Cancer Survival: A Systematic Review and Meta-Analysis of Cohort Studies

Background:

A number of observational studies examined the association between metformin therapy and ovarian cancer survival outcomes, but the results are inconsistent.

Objective:

The study aimed to investigate the effect of metformin on survival for ovarian cancer patients.

Methods:

PubMed, Embase and Web of Science databases were searched for relevant studies from the inception to June 11, 2019. The strength of the relationship was assessed using summary of hazard ratios (HRs) with corresponding 95% confidence intervals (CI). Statistical analyses were carried out using the random-effects model.

Results:

Totally, 6 retrospective cohort studies involving 2,638 ovarian cancer patients were included. Metformin was not associated with improved overall survival (HR=0.78, 95% CI 0.54-1.12, P=0.175, I2= 61.6%) and disease- free survival (HR=0.49, 95% CI 0.20-1.17, P=0.106, I2=82.1%) in ovarian cancer patients compared to nonmetformin users.

Conclusion:

The current study provides preliminary evidence that metformin may not be associated with a survival benefit for ovarian cancer patients. More studies with rigorous designs are needed.