Body mass index, comorbidities, and hormonal factors in relation to meningioma in an ethnically diverse population: the Multiethnic Cohort

Lifestyle and metabolic factors affect risk for meningioma in women: a prospective population-based study (The Cohort of Norway)

Background

Meningioma is the most common primary brain tumor, with a clear preponderance in women. Obesity is considered a risk factor for the development of meningioma. Obesity is also the clinical hallmark of metabolic syndrome, characterized by glucose intolerance, dyslipidemia, and hypertension. Lifestyle and metabolic factors directly impact overweight and obesity and are therefore potential risk factors for meningioma development. The aim of this study is to assess lifestyle and metabolic factors for meningioma risk in women.

Methods

The Cohort of Norway (CONOR) is a nationwide health survey, conducted between 1994 and 2003, including anthropometric measures, blood tests, and health questionnaires. Linkage to the National Cancer Registry enabled the identification of intracranial meningioma during follow-up until December 2018.

Results

A total of 81,652 women were followed for a combined total of 1.5 million years, and 238 intracranial meningiomas were identified. Increasing levels of physical activity (HR 0.81; 95% CI 0.68-0.96; p trend <0.02) and parity (HR 0.83; 95% CI 0.71-0.97; p trend <0.03) were negatively associated with meningioma risk. Diabetes mellitus or glucose intolerance increased the risk for meningioma (HR 2.54; 95% CI 1.60-4.05). Overweight and obesity were not associated with meningioma risk, nor was metabolic syndrome. However, participants without metabolic dysfunction had a reduced meningioma risk, while participants with all five metabolic factors present had a 4-fold risk increase for meningioma (HR 4.28; 95% CI 1.34-13.68).

Conclusion

Lifestyle factors seem to significantly influence meningioma risk. However, disentangling the complex associations and interactions between factors for meningioma risk will be a challenging task for future studies.

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.

Meningioma and Other Meningeal Tumors

Meningiomas develop from meningothelial cells and approximately account for more than 30 percent of central nervous system (CNS) tumors. They can occur anywhere in the dura, most often intracranially and at dural reflection sites. Half of the cases are usually at parasagittal/falcine and convexity locations; other common sites are sphenoid ridge, suprasellar, posterior fossa, and olfactory groove. The female-to-male ratio is approximately 2 or 3-1, and the median age at diagnosis is 65 years. Meningiomas are generally extremely slow-growing tumors; many are asymptomatic or paucisymptomatic at diagnosis and are discovered incidentally. Clinical manifestations, when present, are influenced by the tumor site and by the time course over which it develops. Meningiomas are divided into three grades. Grade I represents the vast majority of cases; they are considered typical or benign, although their CNS location can still lead to severe morbidity or mortality, resulting in a reported ten-year net survival of over 80%. Atypical (WHO grade II) meningiomas are considered "intermediate grade" malignancies and represent 5-7% of cases. They show a tendency for recurrence and malignant degeneration with a relevant increase in tumor cell migration and surrounding tissue infiltration; ten-year net survival is reported over 60%. The anaplastic subtype (WHO III) represents only 1-3% of cases, and it is characterized by a poor prognosis (ten-year net survival of 15%). The treatment of choice for these tumors stands on complete microsurgical resection in case the subsequent morbidities are assumed minimal. On the other hand, and in case the tumor is located in critical regions such as the skull base, or the patient may have accompanied comorbidities, or it is aimed to avoid intensive treatment, some other approaches, including stereotactic radiosurgery and radiotherapy, were recommended as safe and effective choices to be considered as a primary treatment option or complementary to surgery. Adjuvant radiosurgery/radiotherapy should be considered in the case of atypical and anaplastic histology, especially when a residual tumor is identifiable in postoperative imaging. A "watchful waiting" strategy appears reasonable for extremely old individuals and those with substantial comorbidities or low-performance status, while there is a reduced threshold for therapeutic intervention for relatively healthy younger individuals due to the expectation that tumor progression will inevitably necessitate proactive treatment. To treat and manage meningioma efficiently, the assessments of both neurosurgeons and radiation oncologists are essential. The possibility of other rarer tumors, including hemangiopericytomas, solitary fibrous tumors, lymphomas, metastases, melanocytic tumors, and fibrous histiocytoma, must be considered when a meningeal lesion is diagnosed, especially because the ideal diagnostic and therapeutic approaches might differ significantly in every tumor type.

ITF2357 induces cell cycle arrest and apoptosis of meningioma cells via the PI3K-Akt pathway

As a type of central nervous system tumor, meningioma usually compresses the nerve center due to its local expansion, further causing neurological deficits. However, there are limited therapeutic approaches for meningiomas. ITF2357, a potent class I and II histone deacetylase inhibitor (HDACi), has been shown to inhibit cell proliferation, promote apoptosis, and block the cell cycle in various sarcoma cells, including glioblastoma and peripheral T-cell lymphoma. Here, we investigated the potential role of ITF2357 on meningioma cancer cells (IOMM-Lee cells). First, we demonstrated that the half-maximal inhibitory concentration (IC50) of ITF2357 was 1.842 μM by MTT assay. In addition, ITF2357 effectively inhibited the proliferation and colonization ability of IOMM-Lee cells. Flow cytometry analysis showed that ITF2357 induced G0/G1 and G2/M phase cell cycle arrest and cell apoptosis. Mechanically, the RNA sequencing data revealed that ITF2357 could affect the PI3K-Akt signaling pathway and the cell cycle progression. Furthermore, the expression levels of Akt, PI3K, p-Akt, and p-PI3K were determined by western blotting. Collectively, our data revealed that ITF2357 induces G0 G1 and G2/M phase arrest and apoptosis by inhibiting hyperactivation of the PI3K-Akt pathway, ultimately inhibiting cell viability and proliferation of meningioma cells, which developed a new approach to the treatment of meningioma.

Optimal annual body mass index change for preventing spontaneous preterm birth in a subsequent pregnancy

Preterm birth (PTB) is a leading cause of neonatal morbidity and mortality. Although PTB is known to recur, interpregnancy preventive strategies for PTB have not been established to date. Annual BMI change can serve as a specific target value for preventing obstetric complications during interpregnancy care/counseling. This value can also account for age-related weight gain (0.2 kg/m²/year). In a multicenter retrospective study, we investigated the optimal annual BMI change for preventing PTB recurrence using the data of individuals who had two singleton births from 2009 to 2019. The association between annual BMI change and spontaneous PTB (sPTB) was analyzed by separating cases of medically indicated PTB (mPTB) from those of sPTB. Previous history of sPTB was strongly associated with sPTB in the subsequent pregnancy (adjusted odds ratio [aOR], 12.7; 95% confidence interval [CI], 6.5-24.8). Increase in annual BMI was negatively associated with sPTB (aOR, 0.6; 95% CI 0.5-0.9). The sPTB recurrence rate was significantly lower in patients with an annual BMI change of ≥ 0.25 kg/m²/year than in those with an annual BMI change of < 0.25 kg/m²/year (7.7% vs. 35.0%, p = 0.011). Our findings suggest that age-related annual BMI gain between pregnancies may help prevent sPTB recurrence.

Plasma concentration of Bisphenol A and leptin in patients with meningioma and glioma: A pilot study

PURPOSE

Recent increase in incidence of meningiomas suggests the need to search for new risk factors. Leptin, a potentially pro-angiogenic and proliferative agent, could be a candidate for this role, as its expression correlates with body mass index (BMI). Because development of meningioma has also been linked to sex hormones, bisphenol A (BPA), a known xenoestrogen, can also be taken into consideration as a potential risk factor. The aim of this study was to determine plasma concentrations of both substances in patients with meningiomas and to match it to patients with gliomas - a group of brain tumors less hormone- and BMI-dependent.

MATERIALS & METHODS

Concentrations of BPA and leptin were measured in plasma of 24 patients with low grade meningioma and in 29 patients with glioma, using gas chromatography-mass spectrometry (GC-MS) and ELISA kits, respectively. The concentrations of both substances in patients with neoplasms were interpreted in relation to their concentration in healthy population, published in recent reports.

RESULTS

Free and conjugated BPA were present in both meningioma and glioma patients. Moreover, their concentrations far exceeded those reported in the healthy population. Nevertheless, the level of leptin revealed to be significantly higher in meningioma patients than in glioma patients.

CONCLUSIONS

Occurrence of both meningioma and glioma may be accompanied by increased concentrations of leptin and BPA. Further large-scale studies are needed to clarify whether the presence of both substances may play a role in pathogenesis or influence clinical course in patients with brain neoplasms.

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.

Annual Body Mass Index Gain and Risk of Gestational Diabetes Mellitus in a Subsequent Pregnancy

Introduction

Weight change during the interpregnancy is related to gestational diabetes mellitus (GDM) in the subsequent pregnancy. In interpregnancy care/counseling, the timeframe for goal setting is important, while the timing of the next conception is unpredictable and preventing age-related body weight gain is difficult. This study aimed to investigate the association between annual weight gain during the interpregnancy, which provide clearer timeframe, and GDM in subsequent pregnancies.

Methods

This multicenter retrospective study was conducted by collecting data on two pregnancies of the same women in 2009-2019. The association between annual BMI gain and GDM during the subsequent pregnancy was examined.

Results

This study included 1,640 pregnant women. A history of GDM [adjusted odds ratio (aOR), 26.22; 95% confidence interval (CI), 14.93-46.07] and annual BMI gain (aOR, 1.48; 95% CI, 1.22-1.81) were related to GDM during the subsequent pregnancy. In the women with a pre-pregnant BMI of <25.0 kg/m2 and without GDM during the index pregnancy, an annual BMI gain of ≥0.6 kg/m2/year during the interpregnancy were associated with GDM in subsequent pregnancies; however, in the other subgroups, it was not associated with GDM in subsequent pregnancies.

Conclusions

For women with a pre-pregnant BMI of <25.0 kg/m2 and without GDM during the index pregnancy, maintaining an annual BMI gain of <0.6 kg/m2/year may prevent GDM during the subsequent pregnancy.

Annual body mass index gain and risk of hypertensive disorders of pregnancy in a subsequent pregnancy

Weight gain during interpregnancy period is related to hypertensive disorders of pregnancy (HDP). However, in interpregnancy care/counseling, the unpredictability of the timing of the next conception and the difficulties in preventing age-related body weight gain must be considered while setting weight management goals. Therefore, we suggest considering the annual change in the body mass index (BMI). This study aimed to clarify the association between annual BMI changes during the interpregnancy period and HDP risk in subsequent pregnancies. A multicenter retrospective study of data from 2009 to 2019 examined the adjusted odds ratio (aOR) of HDP in subsequent pregnancies. The aORs in several annual BMI change categories were also calculated in the subgroups classified by HDP occurrence in the index pregnancy. This study included 1,746 pregnant women. A history of HDP (aOR, 16.76; 95% confidence interval [CI], 9.62 - 29.22), and annual BMI gain (aOR, 2.30; 95% CI, 1.76 - 3.01) were independent risk factors for HDP in subsequent pregnancies. An annual BMI increase of ≥ 1.0 kg/m2/year was related to HDP development in subsequent pregnancies for women without a history of HDP. This study provides data as a basis for interpregnancy care/counseling, but further research is necessary to validate our findings and confirm this relationship.

A decreased risk of meningioma in women smokers was only observed in American studies rather than studies conducted in other countries: a systematic review and meta-analysis

Background

Whether smoking is related to a decreased risk of meningioma in women is still controversial. We conducted a systematic review and meta-analysis examining the association between smoking and risk of meningiomas in women.

Methods

Two authors independently performed a systematic literature review in the PubMed, Cochrane Library, and EMBASE databases. We identified case-control and cohort studies quantifying associations between smoking and risk of meningioma in women. A meta-analysis by pooling studies was performed according to the multivariate-adjusted risk estimates and 95% confidence intervals (CIs) preferentially. We further conducted additional subgroup and sensitivity analyses to explore possible explanations of the results.

Results

A total of seven observational studies were included, with a total of 2132 female patients diagnosed with meningiomas. Ever smoking was associated with a significantly reduced risk of meningioma in women, with pooled odds ratio (OR) of 0.83 (95% CI 0.70–0.98). Similar findings were noted for current (OR 0.78, 95% CI 0.66–0.93) and past (OR 0.82, 95% CI 0.71–0.94) smokers. However, considering the areas, the OR of ever smoking was 0.77 (95% CI 0.68–0.87) in three American studies, but 0.99 (95% CI 0.73–1.35) in four studies conducted in other countries.

Conclusions

Based on limited epidemiological evidence, a decreased risk of meningioma in women smokers was only observed in American studies rather than studies conducted in other countries.

Mitochondrial DNA sequence variation and risk of meningioma

BACKGROUND

Risk factors for meningioma include female gender, African American race, high body mass index (BMI), and exposure to ionizing radiation. Although genome-wide association studies (GWAS) have identified two nuclear genome risk loci for meningioma (rs12770228 and rs2686876), the relation between mitochondrial DNA (mtDNA) sequence variants and meningioma is unknown.

METHODS

We examined the association of 42 common germline mtDNA variants (minor allele frequency ≥ 5%), haplogroups, and genes with meningioma in 1080 controls and 478 meningioma cases from a case-control study conducted at medical centers in the southeastern United States. Associations were examined separately for meningioma overall and by WHO grade (n = 409 grade I and n = 69 grade II/III).

RESULTS

Overall, meningioma was significantly associated with being female (OR 2.85; 95% CI 2.21-3.69), self-reported African American race (OR 2.38, 95% CI 1.41-3.99), and being overweight (OR 1.48; 95% CI 1.11-1.97) or obese (OR 1.70; 95% CI 1.25-2.31). The variant m.16362T > C (rs62581341) in the mitochondrial control region was positively associated with grade II/III meningiomas (OR 2.33; 95% CI 1.14-4.77), but not grade I tumors (OR 0.99; 95% CI 0.64-1.53). Haplogroup L, a marker for African ancestry, was associated with meningioma overall (OR 2.92; 95% CI 1.01-8.44). However, after stratifying by self-reported race, this association was only apparent among the few self-reported Caucasians with this haplogroup (OR 6.35; 95% CI 1.56-25.9). No other mtDNA variant, haplogroup, or gene was associated with meningioma.

CONCLUSION

Common mtDNA variants and major mtDNA haplogroups do not appear to have associations with the odds of developing meningioma.

Association between Airport-Related Ultrafine Particles and Risk of Malignant Brain Cancer: A Multiethnic Cohort Study

Ultrafine particles (UFP; diameter less than or equal to 100 nm) may reach the brain via systemic circulation or the olfactory tract and have been implicated in the risk of brain tumors. The effects of airport-related UFP on the risk of brain tumors are not known. Here we determined the association between airport-related UFP and risk of incident malignant brain cancer (n = 155) and meningioma (n = 420) diagnosed during 16.4 years of follow-up among 75,936 men and women residing in Los Angeles County from the Multiethnic Cohort study. UFP exposure from aircrafts was estimated for participants who lived within a 53 km × 43 km grid area around the Los Angeles International Airport (LAX) from date of cohort entry (1993-1996) through December 31, 2013. Cox proportional hazards models were used to estimate the effects of time-varying, airport-related UFP exposure on risk of malignant brain cancer and meningioma, adjusting for sex, race/ethnicity, education, and neighborhood socioeconomic status. Malignant brain cancer risk in all subjects combined increased 12% [95% confidence interval (CI), 0.98-1.27] per interquartile range (IQR) of airport-related UFP exposure (∼6,700 particles/cm³) for subjects with any address in the grid area surrounding the LAX airport. In race/ethnicity-stratified analyses, African Americans, the subgroup who had the highest exposure, showed a HR of 1.32 (95% CI, 1.07-1.64) for malignant brain cancer per IQR in UFP exposure. UFP exposure was not related to risk of meningioma overall or by race/ethnicity. These results support the hypothesis that airport-related UFP exposure may be a risk factor for malignant brain cancers. SIGNIFICANCE: Malignant brain cancer risk increases with airport-related UFP exposure, particularly among African Americans, suggesting UFP exposure may be a modifiable risk factor for malignant brain cancer.

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 risk of developing a meningioma during and after pregnancy

Pregnancy has been associated with diagnosis or growth of meningiomas in several case reports, which has led to the hypothesis that pregnancy may be a risk factor for meningiomas. The aim of this study was to test this hypothesis in a large population-based cohort study. Women born in Sweden 1958–2000 (N = 2,204,126) were identified and matched with the Medical Birth Register and the Cancer Register. The expected number of meningioma cases and risk ratios were calculated for parous and nulliparous women and compared to the observed number of cases. Compared to parous women, meningiomas were more common among nulliparous (SIR = 1.73; 95% CI 1.52–1.95). The number of meningioma cases detected during pregnancy was lower than the expected (SIR = 0.40; 95% CI 0.20–0.72). Moreover, no increased risk was found in the first-year post-partum (SIR = 1.04; 95% CI 0.74–1.41). Contrary to our hypothesis, there was no increased risk for diagnosing a meningioma during pregnancy or 1-year post-partum. A lower detection rate during pregnancy, may reflect under-utilization of diagnostic procedures, but the actual number of meningiomas was homogenously lower among parous than nulliparous women throughout the study period, indicating that pregnancy is not a risk factor for meningioma.

Meningioma: A Review of Epidemiology, Pathology, Diagnosis, Treatment, and Future Directions

Meningiomas are the most common intracranial tumor, making up more than a third of all primary central nervous system (CNS) tumors. They are mostly benign tumors that can be observed or preferentially treated with gross total resection that provides good outcomes. Meningiomas with complicated histology or in compromising locations has proved to be a challenge in treating and predicting prognostic outcomes. Advances in genomics and molecular characteristics of meningiomas have uncovered potential use for more accurate grading and prediction of prognosis and recurrence. With the study and detection of genomic aberrancies, specific biologic targets are now being trialed for possible management of meningiomas that are not responsive to standard surgery and radiotherapy treatment. This review summarizes current epidemiology, etiology, molecular characteristics, diagnosis, treatments, and current treatment trials.

Body mass index as an independent prognostic factor in glioblastoma

PURPOSE

Glioblastoma prognosis remains dismal despite gross total removal (GTR) followed by chemoradiotherapy. Other known prognostic factors include functional status, age and IDH mutation status. However, to improve patient outcome, a search for other features with impact on survival is needed. We aimed to analyse the impact of body mass index (BMI) on overall survival (OS) and progression-free survival (PFS) of surgically resected primary glioblastoma and evaluate if BMI constitutes an independent prognostic factor.

METHODS

We analysed all adult glioblastoma patients who underwent surgery and chemoradiotherapy between 2011 and 2017 at our institution. Overall survival was the study-primary endpoint, and progression-free survival-the secondary endpoint. We assayed age, gender, histology, extent of resection, IDH, functional and smoking status, cardiovascular risk factors, BMI, OS and PFS. Univariate analysis was conducted followed by multivariate analysis to establish independent prognostic factors. In accordance with the World Health Organization (WHO) BMI stratification, survival curves were obtained for normal-weight (18.5-24.9 kg/m²), overweight (25-29.9 kg/m²) and obese (≥ 30 kg/m²) patient subgroups in addition to the non-obese (18.5-29.9 kg/m²) population.

RESULTS

193 patients were evaluated, with a median follow-up time of 17.3 months. Median OS was 21.3 months in obese patients vs 16.2 months in the non-obese (p = 0.017) and 16 months in the normal weight (p = 0.007). Higher median OS was also observed in patients under 60 and those in which GTR was obtained. Median PFS in obese individuals was 9 months in comparison to 6 months in the normal-weight subgroup (p = 0.04) and 7 months in the non-obese (p = 0.050). Multivariate analysis identified age < 60 (p = 0.044), GTR (p = 0.004) and BMI ≥ 30 (p = 0.009) as independent prognostic factors for increased overall survival.

CONCLUSION

Higher BMI was associated with longer OS and PFS. Prospective studies are needed to validate these findings.

A Practical Overview on the Molecular Biology of Meningioma

PURPOSE OF REVIEW

Meningioma is a common intracranial neoplasm currently classified in 15 histologic subtypes across 3 grades of malignancy. First-choice therapy for meningioma is maximum safe resection for grade I tumors, and surgery plus optional and mandatory adjuvant radiotherapy for grade II and III, respectively, given the increased rate of recurrence even in the event of complete resection. The WHO 2016 histopathologic grading of meningioma has been questioned due to subjectivity and its controversial predictive power for recurrence.

RECENT FINDINGS

Novel DNA methylation profiling has simplified classification into six classes that seem to improve prognostic accuracy. We review five main topics of molecular biology research regarding tumorigenesis and natural history of meningioma from the clinician's perspective: the histopathologic diagnostic features and pitfalls of the current tumor classification; the molecular integrated diagnosis supported by identification of genetic alterations and DNA methylation profiling; the general landscape of the various signaling pathways involved in meningioma formation; the pathogenic theories of the peri-tumoral edema present in meningioma and its therapy implications; and a summarized review on the current treatments and plausible targeted therapies directed to meningioma. It seems likely that molecular assessment will be introduced within the next update of the WHO classification of meningiomas, acknowledging the promising value of DNA methylation profiling. This integrated diagnostic protocol will simplify tumor subtype categorization and provide improved accuracy in predicting recurrence and outcome. Although much effort is being done in identifying key gene mutations, and elucidating specific intracellular signaling pathways involved in meningioma tumorigenesis, effective targeted therapies for recurrent meningiomas are still lacking.

Estrogen hormone replacement therapy in incidental intracranial meningioma: a growth-rate analysis

Incidental meningiomas (IMs) are the most common intracranial neoplasms, especially in perimenopausal women. There is ongoing debate on whether their incidence is increased by hormone replacement therapy. Meningiomas often express estrogen receptors, which were linked to higher proliferative activity according to some reports. Consequently, there is a theoretical risk of estrogen-based HRT (e-HRT) leading to an increase in tumor growth and thus altering the natural history of IMs. However, clinical data is lacking to support this notion. To identify differences in the natural history of IM after e-HRT exposure. We queried the NorthShore Meningioma Database for patients with ≥ 6 months of e-HRT. They were compared with age-matched IM controls. Forty patients were included in the e-HRT group (mean age 62.1 ± 12.0 years; mean duration of HRT 5.3 ± 4.5 years) and 80 in the no-HRT group (mean age 62.2 ± 12 years). Radiographic appearance was similar between groups. The average 2D tumor diameter was 35% lower in the e-HRT group (p = 0.02), with an absolute growth-rate of half of the no-HRT group (p = 0.02). Radiographic and clinical progression-free survival were 1.2 years and 3.3 years longer in the e-HRT group, respectively. These preliminary results suggest that e-HRT may be safe in incidental meningiomas.

Multi-Omics Analysis in Initiation and Progression of Meningiomas: From Pathogenesis to Diagnosis

Meningiomas are common intracranial tumors that can be cured by surgical resection in most cases. However, the most disconcerting is high-grade meningiomas, which frequently recur despite initial successful treatment, eventually conferring poor prognosis. Therefore, the early diagnosis and classification of meningioma is necessary for the subsequent intervention and an improved prognosis. A growing body of evidence demonstrates the potential of multi-omics study (including genomics, transcriptomics, epigenomics, proteomics) for meningioma diagnosis and mechanistic links to potential pathological mechanism. This thesis addresses a neglected aspect of recent advances in the field of meningiomas at multiple omics levels, highlighting that the integration of multi-omics can reveal the mechanism of meningiomas, which provides a timely and necessary scientific basis for the treatment of meningiomas.

Total DNA methylation as a biomarker of DNA damage and tumor malignancy in intracranial meningiomas

Background

Meningiomas are the most common primary intracranial tumors in adults. They are initially detected with neuroimaging techniques, but definite histological diagnosis requires tumor surgery to collect tumor tissue. Gross total resection is an optimal and final treatment for the majority of patients, followed by radiotherapy in malignant or refractory cases. However, there are a lot of uncertainties about i.a. the need for intervention in incidental cases, estimation of growth kinetics, risk of malignant transformation, or response to radiotherapy. Therefore a new diagnostic approach is needed. It has already been shown that epigenetics plays a crucial role in cancer biology, development, and progression. DNA methylation, the presence of 5-methylcytosine in DNA, is one of the main elements of a broad epigenetic program in a eukaryotic cell, with superior regulatory significance. Therefore, we decided to look at meningioma through changes of 5-methylcytosine.

Methods

We performed an analysis of the total amount of 5-methylcytosine in DNA isolated from intracranial meningioma tissues and peripheral blood samples of the same patients. The separation and identification of radioactively labeled nucleotides were performed using thin-layer chromatography.

Results

We found that the 5-methylcytosine level in DNA from intracranial meningiomas is inversely proportional to the malignancy grade. The higher the tumor WHO grade is, the lower the total DNA methylation. The amount of 5-methylcytosine in tumor tissue and peripheral blood is almost identical.

Conclusions

We conclude that the total DNA methylation can be a useful marker for brain meningioma detection, differentiation, and monitoring. It correlates with tumor WHO grade, and the 5-methylcytosine level in peripheral blood reflects that in tumor tissue. Therefore it’s applicable for liquid biopsy.

Our study creates a scope for further research on epigenetic mechanisms in neurooncology and can lead to the development of new diagnostic methods in clinical practice.

Association Between Outdoor Air Pollution and Risk of Malignant and Benign Brain Tumors: The Multiethnic Cohort Study

Background

There are increasing concerns about the potential impact of air pollution on chronic brain inflammation and microglia cell activation, but evidence of its carcinogenic effects is limited.

Methods

We used kriging interpolation and land use regression models to estimate long-term air pollutant exposures of oxides of nitrogen (NO_x, NO₂), kriging interpolation for ozone (O₃), carbon monoxide, and particulate matter (PM_2.5, PM₁₀), and nearest monitoring station measurements for benzene for 103 308 men and women from the Multiethnic Cohort, residing largely in Los Angeles County from recruitment (1993–1996) through 2013. We used Cox proportional hazards models to examine the associations between time-varying pollutants and risk of malignant brain cancer (94 men, 116 women) and meningioma (130 men, 425 women) with adjustment for sex, race and ethnicity, neighborhood socioeconomic status, smoking, occupation, and other covariates. Stratified analyses were conducted by sex and race and ethnicity.

Results

Brain cancer risk in men increased in association with exposure to benzene (hazard ratio [HR] = 3.52, 95% confidence interval [CI] = 1.55 to 7.55) and PM₁₀ (HR = 1.80, 95% CI = 1.00 to 3.23). Stronger associations with PM₁₀ (HR = 3.02, 95% CI = 1.26 to 7.23), O₃ (HR = 2.93, 95% CI = 1.09 to 7.88), and benzene (HR = 4.06, 95% CI = 1.17 to 18.2) were observed among Latino men. Air pollution was unrelated to risk of meningioma except that O₃ exposure was associated with risk in men (HR = 1.77, 95% CI = 1.02 to 3.06). Brain cancer risk in women was unrelated to air pollution exposures.

Conclusions

Confirmation of these sex differences in air pollution–brain cancer associations and the stronger findings in Latino men in additional diverse populations is warranted.

Risk factors for childhood and adult primary brain tumors

Primary brain tumors account for ~1% of new cancer cases and ~2% of cancer deaths in the United States; however, they are the most commonly occurring solid tumors in children. These tumors are very heterogeneous and can be broadly classified into malignant and benign (or non-malignant), and specific histologies vary in frequency by age, sex, and race/ethnicity. Epidemiological studies have explored numerous potential risk factors, and thus far the only validated associations for brain tumors are ionizing radiation (which increases risk in both adults and children) and history of allergies (which decreases risk in adults). Studies of genetic risk factors have identified 32 germline variants associated with increased risk for these tumors in adults (25 in glioma, 2 in meningioma, 3 in pituitary adenoma, and 2 in primary CNS lymphoma), and further studies are currently under way for other histologic subtypes, as well as for various childhood brain tumors. While identifying risk factors for these tumors is difficult due to their rarity, many existing datasets can be leveraged for future discoveries in multi-institutional collaborations. Many institutions are continuing to develop large clinical databases including pre-diagnostic risk factor data, and developments in molecular characterization of tumor subtypes continue to allow for investigation of more refined phenotypes. Key Point 1. Brain tumors are a heterogeneous group of tumors that vary significantly in incidence by age, sex, and race/ethnicity.2. The only well-validated risk factors for brain tumors are ionizing radiation (which increases risk in adults and children) and history of allergies (which decreases risk).3. Genome-wide association studies have identified 32 histology-specific inherited genetic variants associated with increased risk of these tumors.