Diabetes, use of metformin, and the risk of meningioma

Bridging the gap: exploring the causal relationship between metformin and tumors

Objective

Numerous studies have reported that metformin can reduce the risk of tumor development. However, some of the results of these studies are conflicting, necessitating a more reliable evaluation.

Methods

We conducted a Mendelian randomization phenome-wide association study (MR-PheWAS) of tumors to explore the causal relationship between metformin and tumors. Two cohorts of patients taking metformin were obtained from the UK Biobank. Complete phenotype data of the tumors were obtained from FinnGen_R10. We elucidated the causal relationship using a two-sample Mendelian randomization (MR) analysis. More importantly, we conducted a meta-analysis to ensure relatively unbiased results. In the MR analysis, we used the inverse-variance weighted (IVW) method as the main outcome indicator. Subsequently, two cohorts were integrated for the meta-analysis. Finally, we investigated the mechanisms through mediational MR analysis.

Results

MR analysis revealed that metformin might have a causal relationship with 13 tumor-associated phenotypes in the training cohort. Four phenotypes were validated in the testing cohort. In the training and testing cohorts, metformin exhibited a protective effect against brain meningiomas and malignant neoplasms of the breast (HER-positive), oral cavity, tonsils, and the base of the tongue. Intriguingly, after integrating the results of the two cohorts for the meta-analysis, 12 results were statistically significant. Mediational MR analysis suggested that the effects of metformin on brain meningiomas may be weakened by the presence of the family Oxalobacteraceae.

Conclusion

Metformin exhibits potential preventive and therapeutic effects on four types of tumors: brain meningioma, malignant neoplasms of the breast (HER-positive), oral cavity and tonsils, and the base of the tongue. Large randomized controlled trials are required to confirm these findings.

The causal relationship between genetically determined telomere length and meningiomas risk

Background

Studies have shown that longer leukocyte telomere length (LTL) is significantly associated with increased risk of meningioma. However, there is limited evidence concerning the causal association of LTL with benign and malignant meningiomas or with the location of benign tumors.

Methods

We used three LTL datasets from different sources, designated by name and sample size as LTL-78592, LTL-9190, and LTL-472174. The linkage disequilibrium score (LDSC) was used to explore the association between LTL and meningioma. We utilized two-sample bidirectional Mendelian randomization (TSMR) to evaluate whether LTL is causally related to meningioma risk. We adjusted for confounders by conducting multivariable Mendelian randomization (MVMR).

Results

In the LTL-78592, longer LTL was significantly associated with increased risk of malignant [odds ratio (OR) = 5.14, p = 1.04 × 10-5], benign (OR = 4.81, p < 0.05), benign cerebral (OR = 5.36, p < 0.05), and benign unspecified meningioma (OR = 8.26, p < 0.05). The same results were obtained for the LTL-9190. In the LTL-472174, longer LTL was significantly associated with increased risk of malignant (OR = 4.94, p < 0.05), benign (OR = 3.14, p < 0.05), and benign cerebral meningioma (OR = 3.59, p < 0.05). Similar results were obtained in the MVMR. In contrast, only benign cerebral meningioma displayed a possible association with longer LTL (OR = 1.01, p < 0.05). No heterogeneity or horizontal pleiotropy was detected.

Conclusion

In brief, genetically predicted longer LTL may increase the risk of benign, malignant, and benign cerebral meningiomas, regardless of the LTL measure, in European populations.

Five-alpha reductase inhibitors and risk of prostate cancer among men with benign prostatic hyperplasia: A historical cohort study using primary care data

Background: Five-alpha reductase inhibitors (5ARIs) are used in the management of benign prostatic hyperplasia (BPH). 5ARIs prevent the conversion of testosterone to dihydrotestosterone, which is important in prostate development. It has been suggested that 5ARIs can be used a chemopreventative agent for prostate cancer. The aim of this study was to assess the risk of prostate cancer associated with 5ARI use among men with BPH. Methods: Using Clinical Practice Research Datalink (CPRD) from 1992 to 2011 in UK, prostate cancer risk was retrospectively compared in men with a new diagnosis of BPH, with no history of prostate cancer who were treated with 5ARIs, to men treated with alpha blockers (ABs) and those given no pharmacological treatment. Incidence rate of prostate cancer was calculated by treatment group; the association between BPH treatment group and prostate cancer was estimated by a multivariate Cox model. Results: 77,494 men with newly diagnosed BPH were included. The crude incidence rate of prostate cancer was 892.4 cases per 100,000 person-years amongst those treated with 5ARIs, compared with 1209.0 and 1542.9 in those treated with ABs and untreated individuals, respectively. The HR adjusted for potential confounders was 0.79 (0.72-0.86) for 5ARI vs ABs and 0.72 (0.66-0.79) for 5ARI vs untreated. After excluding the first year after BPH diagnosis, adjusted HRs attenuated to 0.87 (0.79-0.97) for 5ARI vs ABs and 0.97 (0.87-1.08) for 5ARI vs untreated. Conclusion: Among men diagnosed with BPH, we found evidence of lower risks of subsequent prostate cancer in those treated with 5ARIs, but this appeared to be driven by cases diagnosed within a year of BPH, possibly reflecting prevalent prostate cancers that were initially misdiagnosed. After excluding the first year after BPH diagnosis, there was little evidence of a reduced prostate cancer risk in those taking 5ARIs.

Correspondence of Meningioma Orbital Grading and Clinicopathological Features among Indonesian Patients

BACKGROUND: Orbital meningiomas can cause visual disturbances, protrusion of the eyes, double vision, and optic nerve abnormalities that significantly decrease vision and eventually lead to blindness. To the best of our knowledge, data on the incidence and pathogenesis of orbital meningioma in Indonesia are non-existent. AIM: This study aimed to analyze the clinicopathological relationship with orbital meningioma grading. METHODS: It is a cross-sectional observational analysis on 44 orbital meningioma patients in Dr. Hasan Sadikin General Hospital and the National Eye Center, Cicendo Eye Hospital in 2017–2020. Chi-square analysis and logistic regression with statistical significance (p < 0.05) were engaged in the method. RESULTS: Orbital meningioma mostly occurred in women aged 30–44 years. Meningioma Grade I was dominated by meningothelial meningioma found in 14 (31.8%) patients, Grade II was atypical meningioma in 9 (20.9%) patients, and Grade III was anaplastic meningioma in 3 patients (6.8%). Clinical symptoms in the form of papillary atrophy (p = 0.046), visual acuity (p = 0.026), proptosis (p = 0.029), and hyperostosis (p = 0.024) were statistically significant and there was a significant difference between Grade I, Grade II, and Grade III using the Chi-square test. Logistic regression results showed that hyperostosis is significantly related to grading the orbital meningioma (p = 0.044) with an odds ratio of 0.206 (IK95% 0.04–0.955). CONCLUSION: Hyperostosis increases the grading of the orbital meningioma because it is related to the invasion of the tumor into the orbital bone and is a neoplastic process. The presence of hyperostosis which is more common in Grade III meningiomas can be used as one of the most important predictors of meningioma recurrence postoperatively. Nonetheless, our data add to the existing literature the potential points of anti-invasive adjuvant therapy attacks.

Natural history of meningiomas: a serial volumetric analysis of 240 tumors

OBJECTIVE

The management of asymptomatic intracranial meningiomas is controversial. Through the assessment of growth predictors, the authors aimed to create the basis for practicable clinical pathways for the management of these tumors.

METHODS

The authors volumetrically analyzed meningiomas radiologically diagnosed at their institution between 2003 and 2015. The primary endpoint was growth of tumor volume. The authors used significant variables from the multivariable regression model to construct a decision tree based on the exhaustive Chi-Square Automatic Interaction Detection (CHAID) algorithm.

RESULTS

Of 240 meningiomas, 159 (66.3%) demonstrated growth during a mean observation period of 46.9 months. On multivariable logistic regression analysis, older age (OR 0.979 [95% CI 0.958-1.000], p = 0.048) and presence of calcification (OR 0.442 [95% CI 0.224-0.872], p = 0.019) had a negative predictive value for tumor growth, while T2-signal iso-/hyperintensity (OR 4.415 [95% CI 2.056-9.479], p < 0.001) had a positive predictive value. A decision tree model yielded three growth risk groups based on T2 signal intensity and presence of calcifications. The median tumor volume doubling time (Td) was 185.7 months in the low-risk, 100.1 months in the intermediate-risk, and 51.7 months in the high-risk group (p < 0.001). Whereas 0% of meningiomas in the low- and intermediate-risk groups had a Td of ≤ 12 months, the percentage was 8.9% in the high-risk group (p = 0.021).

CONCLUSIONS

Most meningiomas demonstrated growth during follow-up. The absence of calcifications and iso-/hyperintensity on T2-weighted imaging offer a practical way of stratifying meningiomas as low, intermediate, or high risk. Small tumors in the low- or intermediate-risk categories can be monitored with longer follow-up intervals.

Characterization of volumetric growth of intracranial meningiomas in Māori and Pasifika populations in New Zealand

BACKGROUND

Māori and Pasifika populations in New Zealand have a higher incidence and prevalence of intracranial meningioma (IM). We sought to evaluate the volumetric growth rate of meningiomas under surveillance in these populations.

METHODS

From July 2002 to October 2020, 336 patients with a total of 408 IM underwent conservative management with serial radiological surveillance at Auckland City Hospital and met the criteria for the study. Inclusion criteria included: age >16 at diagnosis, ≥2 appropriate scans one or more years apart. Exclusion criteria included previous cranial irradiation, a diagnosis of Neurofibromatosis and prior treatment of meningioma. Demographic and clinical data were obtained from the electronic medical records. Imaging data were recorded from the first and last scans. We utilized open-source image processing software (3D Slicer) for semi-automated segmentation and volume calculation. Consistent with previous literature, we calculated the relative growth rate (RGR, %/year) and annual volume change (AVC, cm³ /year) over time.

RESULTS

Four hundred and eight meningiomas were volumetrically characterized for a mean duration of 6.2 years. The Māori and Pasifika populations (n = 134/393) demonstrated a higher RGR (31.41 versus 14.33%/year) (P = 0.026) and AVC (2.05 versus 0.95 cm³ ) (P = 0.025) compared to the control population. They also presented at a younger age and had a higher rate of tumour multiplicity. Males represented only 17.6% of the cohort but exhibited a higher growth rate (AVC = 2.52 cm³ /year) than females (AVC = 0.99 cm³ /year) (P = 0034).

CONCLUSIONS

Māori and Pasifika populations in New Zealand have a higher incidence and volumetric growth rate of IM compared to a control population. This warrants further clinical, histopathological and genomic analysis.

Past medical history of tumors other than meningioma is a negative prognostic factor for tumor recurrence in meningiomas WHO grade I

Background

Prognostic markers for meningioma recurrence are needed to guide patient management. Apart from rare hereditary syndromes, the impact of a previous unrelated tumor disease on meningioma recurrence has not been described before.

Methods

We retrospectively searched our database for patients with meningioma WHO grade I and complete resection provided between 2002 and 2016. Demographical, clinical, pathological, and outcome data were recorded. The following covariates were included in the statistical model: age, sex, clinical history of unrelated tumor disease, and localization (skull base vs. convexity). Particular interest was paid to the patients’ past medical history. The study endpoint was date of tumor recurrence on imaging. Prognostic factors were obtained from multivariate proportional hazards models.

Results

Out of 976 meningioma patients diagnosed with a meningioma WHO grade I, 416 patients fulfilled our inclusion criteria. We encountered 305 women and 111 men with a median age of 57 years (range: 21–89 years). Forty-six patients suffered from a tumor other than meningioma, and no TERT mutation was detected in these patients. There were no differences between patients with and without a positive oncological history in terms of age, tumor localization, or mitotic cell count. Clinical history of prior tumors other than meningioma showed the strongest association with meningioma recurrence (p = 0.004, HR = 3.113, CI = 1.431–6.771) both on uni- and multivariate analysis.

Conclusion

Past medical history of tumors other than meningioma might be associated with an increased risk of meningioma recurrence. A detailed pre-surgical history might help to identify patients at risk for early recurrence.

Metformin Is Associated with a Lower Incidence of Benign Brain Tumors: A Retrospective Cohort Study in Patients with Type 2 Diabetes Mellitus

Background: The risk of benign brain tumors (BBT) associated with metformin use has not received much attention. Therefore, a retrospective cohort study was designed to investigate such an association in patients with type 2 diabetes mellitus (T2DM). Methods: We used the database of Taiwan's National Health Insurance to enroll 152,176 ever users and 16,120 never users of metformin for the follow-up of incidence of BBT and a more specific outcome of cerebral meningioma. The patients were newly diagnosed with T2DM between 1999 and 2005; and they were followed up from 1 January 2006 until 31 December 2011. Hazard ratios were estimated by Cox regression incorporated with the inverse probability of treatment weighting using propensity score. Results: During follow-up, 111 never users and 557 ever users were diagnosed with BBT. For BBT, the respective incidence rates for never users and ever users were 153.95 per 100,000 person-years and 77.61 per 100,000 person-years. While ever users were compared to never users, the hazard ratio was 0.502 (95% confidence interval: 0.409-0.615). A dose-response pattern was seen when ever users were categorized into tertiles of cumulative duration of metformin therapy (cutoffs: <27.10 months, 27.10-58.27 months and >58.27 months) with respective hazard ratios of 0.910 (0.728-1.138), 0.475 (0.375-0.602) and 0.243 (0.187-0.315). For cerebral meningioma, the overall hazard ratio was 0.506 (0.317-0.808); and the hazard ratios comparing the respective tertiles to never users were 0.895 (0.531-1.508), 0.585 (0.346-0.988) and 0.196 (0.104-0.369). Conclusions: A reduced risk of BBT and cerebral meningioma is observed in metformin users in patients with T2DM.

Diabetes increases the risk of meningioma: A systematic review and meta-analysis of observational studies

BACKGROUND

Increasing epidemiological evidence suggests that diabetes may be associated with meningioma risk, but the evidence supporting this association is still inconclusive. Therefore, we performed a meta-analysis of all eligible observational studies to evaluate the potential association of diabetes with meningioma risk.

METHODS

A comprehensive literature search was performed in the PubMed, Web of Science and Cochrane Library databases up to November 30, 2020. A random-effects model was applied to calculate the pooled effect size (ES) and its 95 % confidence interval (CI).

RESULTS

Eight studies were included in this study. In a random-effects pooled analysis, the results showed that DM (diabetes mellitus) increased the risk of meningioma (ES 1.17, 95 % CI: 1.02-1.35, P = 0.027). In subgroup analyses, DM increased the risk of meningioma in women (ES: 1.19, 95 % CI: 1.02-1.40, P = 0.027) and men (ES: 1.53, 95 % CI: 1.25-1.88, P = 0.000). This effect was not observed in the postmenopausal group (ES: 1.18, 95 % CI: 0.64-2.18, P = 0.597).

CONCLUSION

Our meta-analysis showed that DM increases the risk of meningioma, but the association was only present in some subgroups. This conclusion should be further confirmed.

The epidemiology of patients undergoing meningioma resection in Auckland, New Zealand, 2002 to 2011

The incidence of meningioma is known to vary by gender and ethnicity. This study aimed to describe the epidemiological characteristics of a 10-year cohort of patients undergoing meningioma resection at Auckland City Hospital, Auckland, New Zealand. Of particular interest was whether there was any difference in meningioma incidence and recurrence rates between New Zealand Maori and Pacific Island patients compared with other ethnic groups. The study was a retrospective analysis of 493 patients with pathologically confirmed meningioma over the period 1 January 2002 to 31 December 2011. Based on this neurosurgical cohort, the minimum incidence of meningioma in the Auckland region was 3.39 per 100,000 population per year (95% C.I. 3.02-3.80) for the study period. Meningioma was significantly more common in women than men by a ratio of 4.2:1. New Zealand Maori and Pacific Island patients had a significantly higher incidence of meningioma than other ethnic groups. New Zealand Maori had a meningioma incidence 2.74 times that of Europeans (95% C.I. 2.01-3.73, p < 0.001). Pacific Island patients had 2.03 times higher incidence of meningioma than Europeans (95% C.I. 1.42 - 2.89, p < 0.001). The overall meningioma recurrence rate was 21.6% with a mean follow-up of 77 months. Recurrence rates for meningioma among Pacific Island patients were significantly higher than for other ethnic groups (hazard ratio 1.73, p = 0.008). Multivariate analysis of clinical variables confirmed the significance of traditional prognostic factors such as WHO tumour grade and Simpson grade of surgical excision in predicting meningioma recurrence.

HbA1c in patients with intracranial meningiomas WHO grades I and II: A preliminary study

Meningiomas are among the most common primary brain tumors. There is a growing need for novel ways of differentiating between benign (World Health Organization [WHO] grade I) and atypical (WHO grade II) meningiomas as well as for novel markers of the tumor's future behavior. A difference between glucose metabolism in atypical and benign meningiomas is well known. However, a significant correlation between the systemic metabolic status of the patient and the meningioma WHO grade has not yet been established. Our aim was to compare the WHO grades of intracranial meningiomas with the patient's HbA1c levels as a more reliable marker of the chronic systemic metabolic status than the fasting blood glucose value, which is usually looked at. We retrospectively analyzed 15 patients and compared their meningioma WHO grade with their preoperative HbA1c values. Our results show that patients with benign intracranial meningiomas have significantly lower HbA1c value. Conversely, patients with atypical intracranial meningiomas have higher HbA1c values. Furthermore, we showed that the proliferation factor Ki67 was statistically strongly correlated with the HbA1c value (p < .001. These results imply a possible positive correlation between meningioma cell proliferation and the chronic systemic glycemia. Further research in this area could not only lead to better understanding of meningiomas but could have significant clinical application.

Factors Associated With Meningioma Detected in a Population-Based Sample

OBJECTIVE

To determine the frequency of incidental meningioma and identify associated factors in a population-based sample of participants who systematically underwent brain imaging.

PATIENTS AND METHODS

We searched the Mayo Clinic Study of Aging, a population-based sample of Olmsted County, Minnesota, residents who underwent longitudinal magnetic resonance imaging of the brain. Using a text search of radiologists' notes for 2402 individuals (median age, 75.0 years) who underwent imaging between August 10, 2005, and July 31, 2014, we identified 52 patients (2.2%) who had at least one meningioma. We estimated the association of selected risk factors with the presence of meningioma using odds ratios and 95% CIs from logistic regression models adjusted for age and sex. Based on these results, we moved the most significant variables forward to a multivariable model.

RESULTS

Controlling for age and sex, significant associations with the presence of meningioma included higher body mass index (odds ratio [OR], 1.06; 95% CI, 1.01-1.12; P=.03), nonsteroidal anti-inflammatory drugs (OR, 2.11; 95% CI, 1.13-3.95; P=.02), aspirin (OR, 1.90; 95% CI, 1.05-3.46; P=.04), and blood pressure-lowering medication (OR, 2.06; 95% CI, 1.06-3.99; P=.03). Lower risk was associated with male sex (OR, 0.51; 95% CI, 0.29-0.90; P=.02), coronary artery disease (OR, 0.46; 95% CI, 0.22-0.97; P=.04), and higher self-reported anxiety (OR, 0.88; 95% CI, 0.78-0.98; P=.02). Simultaneous adjustment for all of these factors except aspirin in a multivariable model did not attenuate these associations (concordance, 0.71).

CONCLUSION

In a population-based sample of 2402 participants, 52 (2.2%) had an incidental meningioma. They were more likely to be female and have higher body mass index. Meningioma was also associated with certain medications (nonsteroidal anti-inflammatory drugs and blood pressure-lowering medications) and inversely with anxiety and coronary artery disease.

Mendelian randomization provides support for obesity as a risk factor for meningioma

Little is known about the causes of meningioma. Obesity and obesity-related traits have been reported in several epidemiological observational studies to be risk factors for meningioma. We performed an analysis of genetic variants associated with obesity-related traits to assess the relationship with meningioma risk using Mendelian randomization (MR), an approach unaffected by biases from temporal variability and reverse causation that might have affected earlier investigations. We considered 11 obesity-related traits, identified genetic instruments for these factors, and assessed their association with meningioma risk using data from a genome-wide association study comprising 1,606 meningioma patients and 9,823 controls. To evaluate the causal relationship between the obesity-related traits and meningioma risk, we consider the estimated odds ratio (OR) of meningioma for each genetic instrument. We identified positive associations between body mass index (odds ratio [OR_SD] = 1.27, 95% confidence interval [CI] = 1.03–1.56, P = 0.028) and body fat percentage (OR_SD = 1.28, 95% CI = 1.01–1.63, P = 0.042) with meningioma risk, albeit non-significant after correction for multiple testing. Associations for basal metabolic rate, diastolic blood pressure, fasting glucose, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, systolic blood pressure, total cholesterol, triglycerides and waist circumference with risk of meningioma were non-significant. Our analysis provides additional support for obesity being associated with an increased risk of meningioma.

Autophagy Modulation in Cancer: Current Knowledge on Action and Therapy

In the last two decades, accumulating evidence pointed to the importance of autophagy in various human diseases. As an essential evolutionary catabolic process of cytoplasmatic component digestion, it is generally believed that modulating autophagic activity, through targeting specific regulatory actors in the core autophagy machinery, may impact disease processes. Both autophagy upregulation and downregulation have been found in cancers, suggesting its dual oncogenic and tumor suppressor properties during malignant transformation. Identification of the key autophagy targets is essential for the development of new therapeutic agents. Despite this great potential, no therapies are currently available that specifically focus on autophagy modulation. Although drugs like rapamycin, chloroquine, hydroxychloroquine, and others act as autophagy modulators, they were not originally developed for this purpose. Thus, autophagy may represent a new and promising pharmacologic target for future drug development and therapeutic applications in human diseases. Here, we summarize our current knowledge in regard to the interplay between autophagy and malignancy in the most significant tumor types: pancreatic, breast, hepatocellular, colorectal, and lung cancer, which have been studied in respect to autophagy manipulation as a promising therapeutic strategy. Finally, we present an overview of the most recent advances in therapeutic strategies involving autophagy modulators in cancer.