SCLC is thought to originate predominantly from pulmonary neuroendocrine cell and less frequently from surfactant protein C-positive AT2 cell with TP53 and Rb1 loss.79 SCLC can also arise from LUAD via histological transformation through a stem-like intermediate that closely resembles a pulmonary basal cell.80 Indeed, a PLCG2-high SLC population was found to recur across SCLC subtypes and is associated with worse overall survival.9 We identified an SLC cluster that was present across subtypes. This evidence concerns the gene RB1 and small cell lung carcinoma.