CEACAM5 and squamous cell carcinoma: Our findings revealed several key observations: (I) Male sex, current smoking status, higher PET-CT SUVmax, and elevated CEA level were more prevalent in patients with stronger PD-L1 expression; (II) Patients with PD-L1 positive tumors (TPS ≥ 1%) showed a higher frequency of squamous cell carcinoma type, STAS, TP53 mutations, advanced pathological stages, lymph node metastasis, poor cell differentiation, and micropapillary/solid subtype in ADC.