Radiological pure-solid appearance clinical stage I lung adenocarcinoma: a comparative study of mucinous and non-mucinous adenocarcinoma based on imaging features and survival outcomes

OBJECTIVES: Our study aims to compare the clinicopathological, genetic, and prognostic differences between pure-solid appearance clinical stage I mucinous and non-mucinous adenocarcinomas. MATERIALS AND METHODS: Five hundred seventy-nine patients with radiological pure-solid appearance clinical stage I lung adenocarcinoma, were retrospectively evaluated. Clinicopathological, radiological, genetic characteristics, and recurrence patterns were compared between the non-mucinous adenocarcinoma and mucinous adenocarcinoma groups. Recurrence-free survival (RFS) and overall survival (OS) were assessed by Kaplan-Meier curves and compared between groups using log-rank tests. Cox proportional hazard models were used to analyze prognostic factors. RESULTS: Of 579 patients (mean age, 59.9 years ± 9.7 [SD]; 298 women), 442 had non-mucinous adenocarcinoma, and 137 had mucinous adenocarcinoma. The non-mucinous adenocarcinoma group, in comparison with mucinous adenocarcinoma, showed higher CEA levels (p = 0.003), higher CT values (36.88 vs 20.89 HU, p < 0.001), a higher incidence of emphysema (25.1% vs 3.6%, p < 0.001), a lower clinical T stage (51.8% vs 42.3%, p < 0.001), and the absence of air bronchogram (61.3% vs 27%, p < 0.001). Recurrences occurred more frequently in the non-mucinous adenocarcinoma group (38.5%, 170/442) compared to the mucinous adenocarcinoma group (13.1%, 18/137; p < 0.001). Brain metastasis was significantly more common in the non-mucinous adenocarcinoma group (27.1% vs 0%; p = 0.024). Compared with the non-mucinous adenocarcinoma group, the mucinous adenocarcinoma group had better 5-year RFS (86.9% vs 62.7%; p < 0.001) and 5-year OS (97.1% vs 83.2%, p < 0.001). CONCLUSION: Imaging features, survival outcomes, and recurrence patterns differed significantly between mucinous and non-mucinous lung adenocarcinomas. KEY POINTS: Question For radiological pure-solid appearance clinical stage I lung adenocarcinoma, there remains controversy regarding the clinicopathological characteristics and prognosis of mucinous versus non-mucinous subtypes. Findings There were significant differences in clinicopathological features, imaging findings, and recurrence patterns between mucinous and non-mucinous adenocarcinomas. Compared with the non-mucinous adenocarcinoma, the mucinous group had better 5-year RFS and 5-year OS. Critical relevance statement Lung mucinous adenocarcinoma, Lung mucinous adenocarcinoma, due to its unique imaging and clinicopathological features, was a special independent subtype of adenocarcinoma. For radiological pure-solid appearance lung adenocarcinoma, mucinous adenocarcinoma had a better survival prognosis than non-mucinous adenocarcinoma.