The multivariate analysis revealed that a history of antibiotics use, the ECOG PS, cancer stage, number of metastatic organs, brain metastasis, participation in a clinical trial, PD-L1 expression, and the presence of an EGFR mutation were independent predictors of survival (PFS: HR 2.379, 95% CI 1.281–4.418, p = 0.006; OS: HR 3.834, 95% CI 1.736–8.469, p = 0.001) (Table 6). This evidence concerns the gene EGFR and cancer.