Second Primary Lung Cancer in Patients with Laryngeal Squamous Cell Carcinoma: A Retrospective Cohort Study

Patients with laryngeal squamous cell carcinoma (LSCC) often develop other malignancies, most commonly second primary lung cancer (SPLC). This study aimed to estimate the incidence of SPLC in LSCC patients and evaluate whether pulmonary nodules on baseline thoracic computed tomography (CT) predict SPLC development. In this single-center retrospective cohort study, 243 patients with LSCC diagnosed from 2017 to 2024 at the University Hospital of Split, Croatia, were followed, of whom 26 (10.7%) developed SPLC. The median time from LSCC to SPLC diagnosis was approximately 1.2 years. Patients with LSCC had an approximately eightfold higher risk of developing an SPLC than the general population (standardized incidence ratio [SIR] 8.40; 95% confidence interval [CI] 5.48–12.30). Pulmonary nodules at diagnosis were the only predictor associated with the development of an SPLC (hazard ratio [HR] 2.37; 95% CI 1.09–5.13; p = 0.029), although this association weakened and lost significance when the analysis was restricted to metachronous tumors (HR 1.84; 95% CI 0.71–4.77; p = 0.207). Metachronous tumors were predominantly squamous cell carcinomas (83.3%), whereas adenocarcinoma was the most common histological type among synchronous tumors (50.0%; p = 0.022). Patients with SPLC had a shorter overall survival than those without it (median 5.4 vs. 8.0 years; log-rank p = 0.016). The presence of pulmonary nodules at LSCC diagnosis was associated with a higher risk of SPLC. However, these findings originate from a single center, and further studies are needed to determine whether stratification based on initial radiological findings can improve early detection of SPLC in patients with LSCC.