Characteristics of Solid Parts on the Prognosis of Lung Cancer Less Than 2 Cm in Size

Background: Lung cancer patients can have advanced-stages at diagnosis, even the tumor size is <2 cm. Previous studies suggestted that tumor solid part on chest computed tomography (CT) correlated to the clinicopathological features and disease prognosis. Objectives: We aimed to study the relationship between image characteristics, clinical, and histopatholoigcal results. Materials and Methods: We retrospectively enrolled the lung cancer patients at Taichung Veterans General Hospital and Chang Gung Memorial Hospital from 2007 to 2015, who were diagnosed with treatment naïve primary tumor lesions at sizes less than 2 cm, as measured by CT scans. The patients should fulfill clinical N0M0 staging and went through surgical treatment with adequate mediastinal lymph node sampling. We analyzed clinicopathological characteristics, including solid part ratio (SPR) (tumor diameter at the mediastinal/lung window) over chest CT, pathological diagnosis, disease-free survival (DFS), and overall survival (OS). Results: 214 patients were enrolled for analysis. With a SPR ≥25%, significantly worse DFS (HR, 19.23; 95% CI, 2.60–142.01; p=0.004) and a trend of worse OS (HR, 4.97; 95% CI, 0.61–40.61; p=0.134) were noted by Kaplan-Meier method. The DFS and OS showed no significant difference between lobectomy or sublobectomy as surgical methods. SPR ≥25% revealed more pathological lymph node involvement, more angiolymphatic invasion and pleural invasion, and more pathological invasiveness cell types. Conclusion: For lung cancer patients with primary tumor <2 cm, SPR ≥25% was related to more advanced stages, the presence of micropapillary or solid components of adenocarcinoma subtypes, worse DFS, and a trend of worse OS.