The Kaplan–Meier survival curve with log-rank test showed that patients with high-risk scores had shorter OS time than those with low-risk scores (P < 0.001, Fig. 4A), and the AUC of the risk score was 0.689 (Fig. 4C); similarly, the external validation set results were shown in Fig. 4B and D. Then, we analyzed the gene expression in lung adenocarcinoma and normal groups (CTPS2 and DARS2), which had not been fully explored. This evidence concerns the gene CTPS2 and lung adenocarcinoma.