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.

This study examined individual-level determinants of self-reported changes in healthy (diet and physical activity) and addictive (alcohol use, smoking, and vaping) lifestyle behaviors during the initial COVID-19 lockdown period in the USA. A national online survey was administered between May and June 2020 that targeted a representative U.S. sample and yielded data from 1276 respondents, including 58% male and 50% racial/ethnic minorities. We used univariate and multivariable linear regression models to examine the associations of sociodemographic, mental health, and behavioral determinants with self-reported changes in lifestyle behaviors. Some study participants reported increases in healthy lifestyle behaviors since the pandemic (i.e., 36% increased healthy eating behaviors, and 33% increased physical activity). However, they also reported increases in addictive lifestyle behaviors including alcohol use (40%), tobacco use (41%), and vaping (46%). With regard to individual-level determinants, individuals who reported adhering to social distancing guidelines were also more likely to report increases in healthy lifestyle behaviors (β = 0.12, 95% CI 0.04 to 0.21). Conversely, women (β = −0.37, 95% CI −0.62 to −0.12), and unemployed individuals (β = −0.33, 95% CI −0.64 to −0.02) were less likely to report increases in healthy lifestyle behaviors. In addition, individuals reporting anxiety were more likely to report increases in addictive behaviors (β = 0.26, 95% CI 0.09 to 0.43). Taken together, these findings suggest that women and unemployed individuals may benefit from interventions targeting diet and physical activity, and that individuals reporting anxiety may benefit from interventions targeting smoking and alcohol cessation to address lifestyle changes during the pandemic.

Aberrant DNA methylation is a feature of human cancer affecting gene expression and tumor phenotype. Here, we quantified promoter methylation of candidate genes and global methylation in 44 small intestinal-neuroendocrine tumors (SI-NETs) from 33 patients by pyrosequencing. Findings were compared with gene expression, patient outcome and known tumor copy number alterations. Promoter methylation was observed for WIF1, RASSF1A, CTNNB1, CXCL14, NKX2–3, P16, LAMA1, and CDH1. By contrast APC, CDH3, HIC1, P14, SMAD2, and SMAD4 only had low levels of methylation. WIF1 methylation was significantly increased (P = 0.001) and WIF1 expression was reduced in SI-NETs vs. normal references (P = 0.003). WIF1, NKX2–3, and CXCL14 expression was reduced in metastases vs. primary tumors (P < 0.02). Low expression of RASSF1A and P16 were associated with poor overall survival (P = 0.045 and P = 0.011, respectively). Global methylation determined by pyrosequencing of LINE1 repeats was reduced in tumors vs. normal references, and was associated with loss in chromosome 18. The tumors fell into three clusters with enrichment of WIF1 methylation and LINE1 hypomethylation in Cluster I and RASSF1A and CTNNB1 methylation and loss in 16q in Cluster II. In Cluster III, these alterations were low-abundant and NKX2-3 methylation was low. Similar analyses in the SI-NET cell lines HC45 and CNDT2 showed methylation for CDH1 and WIF1 and/or P16, CXCL14, NKX2-3, LAMA1, and CTNNB1. Treatment with the demethylating agent 5-azacytidine reduced DNA methylation and increased expression of these genes in vitro. In conclusion, promoter methylation of tumor suppressor genes is associated with suppressed gene expression and DNA copy number alterations in SI-NETs, and may be restored in vitro.