PL01.06 Molecular Epidemiology of Asian Lung Cancer

Abstract

Lung adenocarcinoma (LADC), the most frequent histological type of lung cancer, develops in both ever- and never-smokers, and has two distinct characteristics in Asian populations. First, the proportion of never-smoking patients is considerably higher than that among individuals of European descent (approximately 40% vs 10%), and the rates of development and death from lung cancer in never-smokers are significantly higher in Asians than those in individuals of European descent. Second, in Asian individuals LADC frequently (in approximately 50% of cases) carries oncogenic mutations of the epidermal growth factor receptor (EGFR) gene, in contrast to lower EGFR mutation rates (approximately 10%) in European/US patients. In Asian patients, EGFR mutation frequently occurs in both never- (60%) and ever- (40%) smokers, while it occurs almost exclusively in European/US ever-smokers. Notably, EGFR-mutated LADC does not respond well to immune checkpoint blockade therapy due to its non-inflamed (immune-cold) features, including low infiltration of CD4+ and CD8+ T cells. Therefore, it is highly likely that there are specific risk factors, independent from smoking, that promote LADC development in Asians and have immunogenic effects influencing tumour characteristics. By conducting genome-wide association study, we demonstrated that HLA loci influence lung adenocarcinoma risk independently from smoking and that the association of HLA-class II, but not class I, loci is more prominent for lung adenocarcinomas with EGFR gene mutations than those without; the HLA-DPB1 Asp57 and 76Val alleles are associated with elevated risk for EGFR-mutated lung adenocarcinoma. HLA variants might influence lung adenocarcinoma risk by modulating anti-tumour immunity.