EGFR and lung cancer: Our PCA score chart showed that under the positive and negative ion modes, the clusters of the EGFR-TKI- and PD-1/PD-L1 inhibitor-treated groups tended to be close to the cluster of the HC group and were significantly separated from the cluster of the primary lung cancer group, indicating that EGFR-TKIs and PD-1/PD-L1 inhibitors have definite antitumor therapeutic effects on NSCLC.