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Analysis of a large group of patients with multifocal premalignant disease by Krysan and colleagues in this issue of Cancer Research provides an informative view of the processes that may underlie progression of these lesions to invasive adenocarcinoma of the lung. The identification of the type and distribution of mutational changes reveals that common processes may be occurring within individuals but that these are generally unique between patients at risk for developing lung cancer. Furthermore, predicted neoantigens are identified and associated with characteristics of immune infiltrates supporting the role of alterations in adaptive immune surveillance in progression of these premalignant lesions. These findings provide critical insights that will help establish a foundation of knowledge for developing personalized prevention strategies with the potential to significantly impact overall mortality in lung cancer. See related article by Krysan et al., p. 5022 ., (©2019 American Association for Cancer Research.)

Background: There is a need for early detection methods for lung cancer. Radiologic imaging may be more sensitive for peripheral cancers than for cancers arising in the central airways, from which bronchial epithelial cells are exfoliated into the sputum., Methods: Sputum samples were collected at baseline and periodically thereafter in a cohort of smokers and former smokers with chronic obstructive lung disease. The association between cytologic atypia and incident lung cancer was assessed by hazard ratios (HR; 95% confidence intervals) using Cox regression and by odds ratios (95% confidence intervals) using logistic regression, adjusting for potential confounding factors., Results: We observed 174 incident lung cancers in a cohort of 2,521 people over 9,869 person-years of observation. Risk for incident lung cancer was increased among those with cytologic atypia graded as moderate or worse (adjusted HR, 2.37; 1.68-3.34). The association between sputum atypia and lung cancer incidence was greatest for those sputum samples collected 5 months or less before the diagnosis of lung cancer (odds ratio, 10.32; 5.34-19.97). The association was substantially stronger for squamous cell lung cancers (HR, 5.13; 2.89-9.10) than for adenocarcinomas (HR, 1.85; 0.94-3.65)., Conclusion: Cytologic atypia is a marker for increased lung cancer risk. These cytologic changes seem to arise from late events that are most apparent for cancers arising in the central respiratory airways. Whether cytologic atypia might complement radiologic imaging in a combined approach to lung cancer, early detection requires additional evaluation of those two methods used together.

Human adenocarcinoma (AC) is the most frequently diagnosed human lung cancer, and its absolute incidence is increasing dramatically. Compared to human lung AC, the A/J mouse-urethane model exhibits similar histological appearance and molecular changes. We examined the gene expression profiles of human and murine lung tissues (normal or AC) and compared the two species' datasets after aligning approximately 7500 orthologous genes. A list of 409 gene classifiers (P value <0.0001), common to both species (joint classifiers), showed significant, positive correlation in expression levels between the two species. A number of previously reported expression changes were recapitulated in both species, such as changes in glycolytic enzymes and cell-cycle proteins. Unexpectedly, joint classifiers in angiogenesis were uniformly down-regulated in tumor tissues. The eicosanoid pathway enzymes prostacyclin synthase (PGIS) and inducible prostaglandin E(2) synthase (PGES) were joint classifiers that showed opposite effects in lung AC (PGIS down-regulated; PGES up-regulated). Finally, tissue microarrays identified the same protein expression pattern for PGIS and PGES in 108 different non-small cell lung cancer biopsies, and the detection of PGIS had statistically significant prognostic value in patient survival. Thus, the A/J mouse-urethane model reflects significant molecular details of human lung AC, and comparison of changes in orthologous gene expression may provide novel insights into lung carcinogenesis.