Lung adenocarcinoma (LUAD), the most common histological subtype of lung cancer(1, 2), is a disease of the elderly, with an average age of diagnosis of about 70 years of age(3). Older age is associated with an increased incidence of KRAS-driven LUAD(4), a particularly deadly type of LUAD characterized by treatment resistance and relapse. Despite this, our understanding of how old age shapes KRAS-driven LUAD evolution remains incomplete. While the age-related increase in cancer risk was previously ascribed to the accumulation of mutations over time, we are now beginning to consider the role of host biology as an independent factor influencing cancer. Here, we use single-cell RNA-Sequencing of KP (Kras