Invasive features of small-sized lung adenocarcinoma adjoining emphysematous bullae

OBJECTIVES: Radiologically small-sized adenocarcinomas are special entities of lung cancer, as their radiological and pathological invasiveness determines the surgical procedures applied; however, the clinicopathological features of small-sized lung adenocarcinoma adjoining cystic airspaces (Ca-ADJ) have yet to be fully clarified. The aim of this study was to elucidate the clinicopathological characteristics, including the programmed death ligand 1 (PD-L1) expression, in patients with Ca-ADJ < 3.0 cm. METHODS: A total of 283 patients with resected adenocarcinoma, whose radiological tumour size was < 3.0 cm without lymph node or distant metastases on preoperative high-resolution computed tomography, were analysed for their clinicopathological and radiological features. Furthermore, the PD-L1 expression was evaluated by immunohistochemistry using an anti-human PD-L1 rabbit monoclonal antibody (clone SP142). RESULTS: Among the 283 patients, 31 (11.0%) patients were reported to have Ca-ADJ. The Fisher's exact test demonstrated that Ca-ADJ was significantly associated with male gender (P < 0.001), a history of smoking (P < 0.001), a high consolidation/tumour ratio (P = 0.026), advanced pathological stage (P < 0.001), the presence of pleural (P < 0.001) and vessel invasion (P < 0.001), histological invasive subtypes (P < 0.001) and wild-type epidermal growth factor receptor (P = 0.001). The patients with Ca-ADJ had a significantly higher maximum standardized uptake value than those without Ca-ADJ (8.4 vs 4.1, P < 0.001). Furthermore, Ca-ADJ was significantly associated with the PD-L1 expression (P < 0.001). Log-rank test showed that patients with Ca-ADJ had a significantly shorter disease-free survival than those without Ca-ADJ (P = 0.001). CONCLUSIONS: This study showed that patients with radiologically small-sized Ca-ADJ might exhibit radiologically and pathologically invasive features.