Simultaneous evaluation of EGFR, ALK, and PD-L1 in lung adenocarcinomas: the largest single-center experience from southern Brazil.

Lung cancer is a highly prevalent disease and the leading cause of cancer-related deaths worldwide. Among non-small cell lung carcinomas (NSCLC), adenocarcinoma is one of the most common subtypes. This retrospective study aimed to analyze the prevalence of epidermal growth factor receptor (EGFR) mutations and programmed death-ligand 1 (PD-L1) expression in patients with confirmed lung adenocarcinoma, based on pathology reports from 2019 to 2024. Patients were assessed by sex, age, PD-L1 expression, and presence of EGFR and ALK mutations. A total of 895 patients were included, mostly male, with an average age of 65.85 years. EGFR mutations were identified in 24.4% of the cases, predominantly exon 19 deletions (50.2%), with women accounting for 70.3% of those mutations. PD-L1 expression, determined by the tumor proportion score (TPS), was high (TPS ≥ 50%) in 28.9%, low (1 ≤ TPS ≤ 49%) in 26.3%, and absent (TPS < 1%) in 44.8% of patients. ALK mutations were found in 5.1% of cases, mostly among younger individuals. Findings on EGFR mutations were consistent with the national and international literature. However, PD-L1 expression rates were higher than those typically reported in Brazilian studies, highlighting regional variation in biomarker prevalence.