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Simple Summary: Since the factors influencing age at diagnosis of lung adenocarcinoma are unknown, in our study, we examined the relationships of age at diagnosis with smoking habit, clinical stage of disease, and sex in Italian and German patients with lung adenocarcinoma who underwent lung adenocarcinoma resection. Our results indicated that smoking habit, advanced clinical stage (more aggressive and larger tumour), and female sex were variables associated with younger age at diagnosis. This study provides new findings on the clinical variables influencing age at diagnosis of lung adenocarcinoma and paves the way for studies on the genetic and molecular mechanisms responsible for these associations. To date, the factors which affect the age at diagnosis of lung adenocarcinoma are not fully understood. In our study, we examined the relationships of age at diagnosis with smoking, pathological stage, sex, and year of diagnosis in a discovery (n = 1694) and validation (n = 1384) series of lung adenocarcinoma patients who had undergone pulmonary resection at hospitals in the Milan area and at Thoraxklinik (Heidelberg), respectively. In the discovery series, younger age at diagnosis was associated with ever-smoker status (OR = 1.5, p = 0.0035) and advanced stage (taking stage I as reference: stage III OR = 1.4, p = 0.0067; stage IV OR = 1.7, p = 0.0080), whereas older age at diagnosis was associated with male sex (OR = 0.57, p < 0.001). Analysis in the validation series confirmed the ever versus never smokers' association (OR = 2.9, p < 0.001), the association with highest stages (stage III versus stage I OR = 1.4, p = 0.0066; stage IV versus stage I OR = 2.0, p = 0.0022), and the male versus female sex association (OR = 0.78, p = 0.032). These data suggest the role of smoking in affecting the natural history of the disease. Moreover, aggressive tumours seem to have shorter latency from initiation to clinical detection. Finally, younger age at diagnosis is associated with the female sex, suggesting that hormonal status of young women confers risk to develop lung adenocarcinoma. Overall, this study provided novel findings on the mechanisms underlying age at diagnosis of lung adenocarcinoma. [ABSTRACT FROM AUTHOR]

Gene expression modulates cellular functions in both physiologic and pathologic conditions. Herein, we carried out a genetic linkage study on the transcriptome of lung tumors induced by urethane in an (A/J x C57BL/6)F4 intercross population, whose individual lung tumor multiplicity (Nlung) is linked to the genotype at the Pulmonary adenoma susceptibility 1 (Pas1) locus. We found that expression levels of 1179 and 1579 genes are modulated by an expression quantitative trait locus (eQTL) in cis and in trans, respectively (LOD score > 5). Of note, the genomic area surrounding and including the Pas1 locus regulated 14 genes in cis and 857 genes in trans. In lung tumors of the same (A/J x C57BL/6)F4 mice, we found 1124 genes whose transcript levels associated with Nlung (FDR < 0.001). The expression levels of about a third of these genes (n = 401) were regulated by the genotype at the Pas1 locus. Pathway analysis of the sets of genes associated with Nlung and regulated by Pas1 revealed a set of 14 recurrently represented genes that are components or targets of the Ras-Erk and Pi3k-Akt signaling pathways. Altogether our results illustrate the architecture of germline control of gene expression in mouse lung cancer: they highlight the importance of Pas1 as a tumor-modifier locus, attribute to it a novel role as a major regulator of transcription in lung tumor nodules and strengthen the candidacy of the Kras gene as the effector of this locus. [ABSTRACT FROM AUTHOR]