Decker, P. A.

Abstract Rationale Rural populations in the US experience a higher lung cancer burden compared to urban residents, potentially due to differences in risk factors and access to preventative care and early detection. We sought to characterize tobacco use, smoking cessation, and lung cancer screening patterns by rurality to identify modifiable gaps in the lung cancer care continuum. Methods We analyzed data from current and former smoking adults in the Southern Community Cohort Study, a large prospective cohort recruited from community health centers across 12 southeastern states. Participants aged 65-80 years with at least 9 months of Medicare Part A/B and less than 3 months of Part C coverage between 2014 and 2020 were included. Data were linked with the National Death Index and Medicare claims for outcome ascertainment. Rurality was defined using Rural-Urban Commuting Area (RUCA) codes. We compared demographic characteristics, smoking patterns, use of smoking cessation interventions, and receipt of low-dose computed tomography (LDCT) screening between rural and urban participants over time. Results Among 10,114 adults included (56% urban; 46% rural), 54% were female, 55% identified as Black/African American, about a third reported less than a high school education, and 45% lived in areas in the highest quartile of deprivation. Urban residents were of similar age (66 vs 67 years), and more likely to currently smoke (42% vs 35%), but had fewer baseline smoking pack-years (27 vs 30 pack-years) than rural residents. Approximately 2% died of lung cancer during follow-up. Using the USPSTF 2013 lung cancer screening criteria, 27% of urban and 26% of rural residents were eligible. This increased unevenly to 38% urban and 35% rural under the USPSTF 2021 criteria. LDCT uptake was low, increasing from 0% in 2014 to 6% in 2020 among screening-eligible participants. Use of cessation interventions was similarly low. Among current smoking participants, 7% received smoking cessation counseling, and 3% had a varenicline prescription. These patterns remained relatively stable over time, with no significant rural-urban differences in LDCT and cessation intervention use. Conclusion Despite modest differences in smoking prevalence and screening eligibility, we found comparable lung cancer mortality and similarly low utilization of LDCT and cessation interventions among rural and urban residents. Our findings suggest that, among people in lower socioeconomic groups, shared socioeconomic constraints may extend beyond the rural-urban divide. Further research is needed to understand how social determinants of health may be addressed to improve lung cancer outcomes across the screening continuum. This abstract is funded by: NIH

Abstract Diffuse hemispheric glioma, H3 G34‐mutant (DHG‐H3 G34) has been primarily molecularly characterized by methylation profiling and sequencing studies. We describe an integrated histomolecular evaluation including high‐resolution copy number profiling of a series of 60 DHG‐H3 G34 to further our understanding of the spectrum of genetic changes associated with this tumor type. Cases were clinically tested using an 187‐gene mutation and fusion targeted neuro‐oncology next‐generation sequencing panel ( n = 60) and Oncoscan chromosomal microarray ( n = 26) by a single laboratory (2018–2022). A subset of cases had immunohistochemical results for OLIG2 ( n = 42), p53 ( n = 48), and ATRX ( n = 46), and methylation array data ( n = 8). Median age at testing was 21 years (range, 12–50). No significant difference was noted in clinical, histopathological, and mutational profile between pediatric and adult patients. H3‐3A G34 mutations included G34R ( n = 56; 94%), G34V ( n = 3), and a non‐canonical G34E ( n = 1). Concurrent mutations most often involved TP53 ( n = 55; 92%), ATRX ( n = 50; 83%), and PDGFRA ( n = 34; 57%). A reportedly primary tumor was confirmed to be hypermutant and had a PMS2 mutation. A single case also showed an FGFR3::FAM184B fusion. All cases with available chromosomal microarray data had unbalanced genomes, which were often complex (14/26; 54%). The most frequent recurrent copy number abnormalities were losses involving 3q, 4q, 10q, 13q, and 18q, and 17p copy‐neutral loss of heterozygosity (cnLOH) encompassing TP53 . This copy number profile was reminiscent of that seen in Grade 4 IDH‐mutant astrocytomas. Collectively, a TP53 abnormality at copy number (12/26, all cnLOH), sequence (55/60) and protein expression (46/48) level was detected in all 60 cases. In conclusion, integrated high‐resolution copy number and histomolecular analysis expanded the spectrum of genetic changes associated with DHG‐H3 G34, including the presence of universal TP53 abnormalities with frequent cnLOH—a copy number abnormality that has been largely unrecognized—for this new 2021 World Health Organization central nervous system tumor type.