Adenosquamous Carcinoma of the Lung: Survival, Radiologic Findings, PD-L1, and Driver Mutations

Background: Adenosquamous carcinoma of the lung (ASC) is a rare non-small-cell lung cancer (NSCLC) subtype combining components of squamous cell carcinoma (SCC) and adenocarcinoma (AC). Data on ASC, particularly in Caucasian populations, are limited. Methods: We reviewed clinicopathological and radiological characteristics of ASC patients diagnosed between 1996 and 2023. Patients were classified into AC-predominant ASC (AC-ASC) and SCC-predominant ASC (SCC-ASC) groups for analysis. Results: Among the 66 patients included, the median overall survival was 41.7 (95% CI, 25.0-54.4), while it was 48.1 (95% CI, 27.3-88.0) in patients treated with curative surgery (n = 44) and 15.3 (95% CI, 6.5-42.6) months for palliative patients (n = 22). The five-year survival rates were 39% and 26%, respectively. Recurrence occurred in 43% of stage I patients and was associated with worse survival (HR 3.303 (95% CI, 1.10-9.89) p = 0.033). AC-ASCs (n = 17) more frequently showed air-bronchogram (p = 0.002) and pleural effusions (p = 0.054) compared to SCC-ASCs (n = 26). SCC-ASCs exhibited more vascular invasion (p = 0.006) and PD-L1 values between 1 and 49% (TPS) (p = 0.032). The subtype did not influence survival. EGFR and ALK alterations were found in 17% and 2% of patients, respectively. Conclusions: Despite early-stage disease, ASC patients had a high recurrence rate, associated with worse survival. Clinicopathologic differences between AC-ASCs and SCC-ASCs did not influence survival.