Metformin and Biliary Tract Cancer in Patients With Type 2 Diabetes

Metformin suppresses gastric cancer progression by disrupting the STAT1-PRMT1 axis

Gastric cancer (GC) is a common form of cancer and the leading cause of cancer-related deaths worldwide. Chemotherapy is the primary treatment for patients with unresectable or partially resectable GC. However, its adverse effects and chemoresistance greatly restrict its applicability and efficacy. Although HER2-targeted therapy and immunotherapy have been successfully used for GC treatment, their beneficial population is limited. To expand the range of cancer treatments, drug repurposing has emerged as a promising strategy. In this study, we evaluated the potential of Metformin, an oral anti-hyperglycemic agent, to suppress GC progression both in vivo and in vitro. Functional investigations showed that Metformin significantly inhibits GC proliferation and migration. Furthermore, we discovered that Metformin bound and disrupted STAT1 phosphorylation, inhibiting PRMT1 expression and consequently GC progression. In conclusion, our study not only provides further evidence for the anti-GC role of Metformin but also identifies the direct target mediating the tumor-inhibitory effects of Metformin in GC.

Removal of intrahepatic bile duct stone could reduce the risk of cholangiocarcinoma: A single-center retrospective study in South Korea

BACKGROUND

Intrahepatic duct (IHD) stones are among the most important risk factors for cholangiocarcinoma (CCC). Approximately 10% of patients with IHD stones develop CCC; however, there are limited studies regarding the effect of IHD stone removal on CCC development.

AIM

To investigate the association between IHD stone removal and CCC development.

METHODS

We retrospectively analyzed 397 patients with IHD stones at a tertiary referral center between January 2011 and December 2020.

RESULTS

CCC occurred in 36 of the 397 enrolled patients. In univariate analysis, chronic hepatitis B infection (11.1% vs 3.0%, P = 0.03), carbohydrate antigen 19-9 (CA19-9, 176.00 vs 11.96 II/mL, P = 0.010), stone located in left or both lobes (86.1% vs 70.1%, P = 0.042), focal atrophy (52.8% vs 26.9%, P = 0.001), duct stricture (47.2% vs 24.9%, P = 0.004), and removal status of IHD stone (33.3% vs 63.2%, P < 0.001) were significantly different between IHD stone patients with and without CCC. In the multivariate analysis, CA19-9 > upper normal limit, carcinoembryonic antigen > upper normal limit, stones located in the left or both lobes, focal atrophy, and complete removal of IHD stones without recurrence were independent factors influencing CCC development. However, the type of removal method was not associated with CCC risk.

CONCLUSION

Complete removal of IHD stones without recurrence could reduce CCC risk.

The impact of diabetes status on total and site-specific cancer risk in the elderly population: A nationwide cohort study

AIMS

We aimed to evaluate the association of prediabetes, diabetes, and diabetes duration with risk of total and site-specific cancer in the Korean population aged 65 years and above.

METHODS

This study included 1,232,173 subjects aged ≥ 65 years who underwent a general health screening program. Diabetes status was categorized as normal glucose tolerance, impaired fasting glucose, new-onset diabetes, diabetes duration of < 5 years, and diabetes duration of ≥ 5 years. Cox proportional hazards models were used to investigate the association of diabetes status with cancer risk.

RESULTS

The risk of total cancer increased as diabetes status worsened, as did the risks of liver, biliary, and pancreatic cancer. Risks of liver, biliary, and pancreatic cancer were significantly higher in subjects aged 65-74 years than in those aged ≥ 75 years. The relationship of diabetes status with overall cancer incidence was found to significantly interact with sex. Among subjects with diabetes, the risks of liver and lung cancer were significantly higher in men than in women regardless of diabetes duration.

CONCLUSIONS

Diabetes status is associated with increased risk of cancer in the elderly. There are age and sex differences in the risk of total and site-specific cancers, including liver, biliary, and pancreatic cancer. This study highlights the importance of cancer screening for elderly subjects with diabetes.

Impact of metformin on the incidence of human cholangiocarcinoma in diabetic patients: a systematic review and meta-analysis

Cholangiocarcinoma (CCA) is the second most common liver cancer. Diabetes is a well-known risk factor; however, treatment with metformin has been reported to be protective for several cancers, but data on CCA are still sparse and heterogeneous. We performed this meta-analysis to investigate the role of metformin as a potential protective factor for CCA. In this systematic review and meta-analysis, we searched PubMed/MEDLINE and EMBASE databases, from the date of inception to November 2022, for studies analyzing CCA rate in patients taking metformin. Twenty-nine articles were initially identified, of which four were eligible and included in our systematic review and meta-analysis, from which we estimated the relative risk (RR). The rate of CCA was lower for diabetic patients taking metformin than diabetic patients without metformin intake when comparing two highest quality studies [RR, 0.38; 95% confidence interval (CI), 0.290-0.508; P < 0.001], and three studies with similar inclusion criteria (RR, 0.34; 95% CI, 0.51-0.35; P < 0.001) without significant statistical heterogeneity among them (I2 = 29.83%, P = 0,2326 and I2 = 35.08%; P = 0.2143, respectively). Our study demonstrated a significant impact of metformin in reducing the risk of CCA by nearly 62-66% in diabetic patients taking metformin.

Effects of Metformin on Risk and Prognosis of Biliary Tract Cancer: A Systematic Review and Meta-Analysis

Background and Objectives: Metformin has been found to potentially reduce the risk and improve the prognosis of a variety of tumors, but these findings remain controversial in biliary tract cancer (BTC). Therefore, this systematic review and meta-analysis was conducted to investigate the association between metformin and BTC. Materials and Methods: Two independent researchers comprehensively searched PubMed, Embase, the Cochrane Library, and Web of Science for eligible studies published from their inception to 31 March 2022. Comparisons of risk, overall survival (OS), and disease-free survival (DFS) for patients with BTC were selected as the endpoints of interest and pooled by random or fixed-effects models. Results: Eleven studies with a total of 24,788,738 participants were eligible for this analysis. The overall pooled effects showed no significant differences in biliary tract cancer risk (hazard ratio (HR) = 0.82, 95% confidence interval (CI): 0.50-1.35, p = 0.436), OS (HR = 0.88, 95% CI: 0.74-1.04, p = 0.135), or DFS (HR = 1.03, 95% CI: 0.79-1.34, p = 0.829) between metformin users and non-users. When restricting participants to those with diabetes, a similar negative result was found, demonstrating that metformin use was not significantly associated with a lower risk of developing BTC compared with a lack of metformin use (HR = 0.65, 95% CI: 0.39-1.07, p = 0.089); notably, the included studies exhibited significant heterogeneity in the selection of participants and the definition of metformin users. Conclusions: Metformin may not be able to reduce the risk of BTC and improve prognosis in certain populations. Based on the limited quantity and quality of the included studies, the present results should be interpreted within their limitations, and further studies are warranted to determine the optimal timing, dose, duration, and scenario of metformin administration.

Metformin Reduces the Risk of Hearing Loss: A Retrospective Cohort Study

OBJECTIVE

To compare the risk of hearing loss with regard to metformin exposure.

STUDY DESIGN

Retrospective cohort.

SETTING

Taiwan's National Health Insurance database.

METHODS

We enrolled 292,071 ever users and 18,200 never users of metformin with new-onset diabetes mellitus from 1999 to 2005 and followed them for hearing loss from January 1, 2006, to December 31, 2011. Hazard ratios (HRs) weighted by propensity score were estimated.

RESULTS

Hearing loss was newly diagnosed in 10,085 ever users and 1072 never users. Their respective incidence rates (per 100,000 person-years) were 738.09 and 1366.83. The HR comparing ever-to-never users was 0.534 (95% confidence interval [CI]: 0.501-0.569]. The HR (95% CI) for the first (<27.07 months), second (27.07-59.13 months), and third (>59.13 months) tertiles of cumulative duration of metformin therapy were 0.912 (0.852-0.975), 0.544 (0.508-0.582), and 0.275 (0.255-0.295), respectively; and were 0.900 (0.841-0.962), 0.531 (0.496-0.569), and 0.293 (0.273-0.315), respectively, for the first (<796.70 g), second (796.70-2020.15 g), and third (>2020.15 g) tertiles of cumulative dose. The magnitude of risk reduction became more remarkable in corresponding to the increasing tertiles of the defined daily dose prescribed. Subtype analyses suggested that the risk reduction was more significant for sensorineural than conductive hearing loss. Findings derived from a propensity score-matched cohort did not substantially change the conclusions, and the risk reduction for mixed hearing loss was not statistically significant in the matched cohort as significantly observed in the unmatched cohort.

CONCLUSION

The risk of hearing loss is reduced in a dose-response pattern in patients who use metformin.

The Risk of Multiple Myeloma Is Reduced in Metformin Initiators: A Retrospective Cohort Study in Taiwanese Patients with Type 2 Diabetes Mellitus

BACKGROUND

Whether metformin might reduce the risk of multiple myeloma (MM) has not been extensively researched in humans.

METHODS

The study subjects were enrolled from the reimbursement database of Taiwan's National Health Insurance. A total of 739,553 patients who had a new diagnosis of type 2 diabetes mellitus during 1999-2009 were identified. They were categorized as metformin initiators (metformin (+)) and non-metformin initiators (metformin (-)) based on the prescriptions of antidiabetic drugs that included metformin and did not include metformin within the initial 12 months, respectively. MM incidence was calculated after the initial 12 months of treatment group assignment until 31 December 2011. Hazard ratios based on intention-to-treat (ITT) and per-protocol (PP) approaches were estimated by Cox regression weighted by propensity scores.

RESULTS

In the ITT analyses, the respective incidence rates for 497,248 metformin (+) and 242,305 metformin (-) were 9.97 and 14.33 per 100,000 person-years. The hazard ratio that compared metformin (+) to metformin (-) in the ITT analysis was 0.710 (95% confidence interval 0.593-0.850). In the PP analysis, the respective incidence rates were 5.14 and 13.98 per 100,000 person-years, and the hazard ratio was 0.355 (95% confidence interval, 0.270-0.466). The lower risk of MM among metformin (+) was supported by subgroup and sensitivity analyses.

CONCLUSIONS

Type 2 diabetes patients who are initiated with metformin treatment have a significantly lower risk of MM, especially when they adhere to metformin treatment.

Metabolic reprogramming in cholangiocarcinoma

Metabolic reprogramming is a hallmark of cancer and allows tumour cells to meet the increased energy demands required for rapid proliferation, invasion, and metastasis. Indeed, many tumour cells acquire distinctive metabolic and bioenergetic features that enable them to survive in resource-limited conditions, mainly by harnessing alternative nutrients. Several recent studies have explored the metabolic plasticity of cancer cells with the aim of identifying new druggable targets, while therapeutic strategies to limit the access to nutrients have been successfully applied to the treatment of some tumours. Cholangiocarcinoma (CCA), a highly heterogeneous tumour, is the second most common form of primary liver cancer. It is characterised by resistance to chemotherapy and poor prognosis, with 5-year survival rates of below 20%. Deregulation of metabolic pathways have been described during the onset and progression of CCA. Increased aerobic glycolysis and glutamine anaplerosis provide CCA cells with the ability to generate biosynthetic intermediates. Other metabolic alterations involving carbohydrates, amino acids and lipids have been shown to sustain cancer cell growth and dissemination. In this review, we discuss the complex metabolic rewiring that occurs during CCA development and leads to unique nutrient addiction. The possible role of therapeutic interventions based on metabolic changes is also thoroughly discussed.

Metformin and Risk of Malignant Brain Tumors in Patients with Type 2 Diabetes Mellitus

The risk of malignant brain tumors associated with metformin use has rarely been investigated in humans. This retrospective cohort study investigated such an association. Patients with new-onset type 2 diabetes mellitus diagnosed from 1999 to 2005 in the nationwide database of Taiwan’s national health insurance were used to enroll study subjects. We first identified an unmatched cohort of 153,429 ever users and 16,222 never users of metformin. A cohort of 16,222 ever users and 16,222 never users matched on propensity score was then created from this unmatched cohort. All patients were followed up from 1 January 2006 until 31 December 2011. The incidence density was calculated and hazard ratios were derived from Cox regression incorporated with the inverse probability of treatment weighting using a propensity score. The results showed that 27 never users and 155 ever users developed malignant brain tumors in the unmatched cohort. The incidence rate was 37.11 per 100,000 person-years in never users and 21.39 per 100,000 person-years in ever users. The overall hazard ratio comparing ever users versus never users was 0.574 (95% confidence interval: 0.381–0.863). The respective hazard ratios comparing the first (<27.13 months), second (27.13–58.33 months), and third (>58.33 months) tertiles of cumulative duration of metformin therapy versus never users were 0.897 (0.567–1.421), 0.623 (0.395–0.984), and 0.316 (0.192–0.518). In the matched cohort, the overall hazard ratio was 0.317 (0.149–0.673) and the respective hazard ratios were 0.427 (0.129–1.412), 0.509 (0.196–1.322), and 0.087 (0.012–0.639) for the first, second, and third tertile of cumulative duration of metformin therapy. In conclusion, this study shows a risk reduction of malignant brain tumors associated with metformin use in a dose–response pattern. The risk reduction is more remarkable when metformin has been used for approximately 2–5 years.

The Relationship between Diabetes Mellitus and Gastric Cancer and the Potential Benefits of Metformin: An Extensive Review of the Literature

The objective of this review is to summarize the findings of published research that investigated the relationship between diabetes mellitus and gastric cancer (GCa) and the potential benefits of metformin on GCa. Related literature has been extensively reviewed, and findings from studies investigating the relationship between diabetes mellitus and GCa suggest that hyperglycemia, hyperinsulinemia and insulin resistance are closely related to the development of GCa. Although not supported by all, most observational studies suggest an increased risk of GCa in patients with type 2 diabetes mellitus, especially in women and in Asian populations. Incidence of second primary malignancy diagnosed after GCa is significantly higher in diabetes patients. Diabetes patients with GCa may have more complications after gastrectomy or chemotherapy and they may have a poorer prognosis than patients with GCa but without diabetes mellitus. However, glycemic control may improve in the diabetes patients with GCa after receiving gastrectomy, especially after procedures that bypass the duodenum and proximal jejunum, such as Roux-en-Y gastric bypass or Billroth II reconstruction. The potential links between diabetes mellitus and GCa may involve the interactions with shared risk factors (e.g., obesity, hyperglycemia, hyperinsulinemia, insulin resistance, high salt intake, smoking, etc.), Helicobacter pylori (HP) infection, medications (e.g., insulin, metformin, statins, aspirin, proton pump inhibitors, antibiotics, etc.) and comorbidities (e.g., hypertension, dyslipidemia, vascular complications, heart failure, renal failure, etc.). With regards to the potential benefits of metformin on GCa, results of most observational studies suggest a reduced risk of GCa associated with metformin use in patients with T2DM, which can be supported by evidence derived from many in vitro and animal studies. Metformin use may also reduce the risk of HP infection, an important risk factor of GCa. In patients with GCa, metformin users may have improved survival and reduced recurrence. More studies are required to clarify the pathological subtypes/anatomical sites of GCa associated with type 2 diabetes mellitus or prevented by metformin, to confirm whether GCa risk can also be increased in patients with type 1 diabetes mellitus and to explore the possible role of gastric microbiota in the development of GCa.