P1.05-07 Clinical Significance of Pleural Indentation of Lung Adenocarcinoma Presented as Ground Glass Opacities

Abstract

After the emphasis on lung cancer screening, incidental detection of ground glass opacities (GGOs) has increased. Such GGOs commonly have peripheral location and pleural indentation, which may increase the risk of visceral pleural invasion (VPI). Although the impact of pleural indentation among solid lung cancers is well established, such impact among GGO lung cancers is not well known. Patients who underwent lung resection with curative intention of GGO lung cancer from April 2007 to January 2016 were retrospectively evaluated. Demographics, radiographic findings, pathological findings, and clinical outcomes including recurrence were analyzed. A total 404 of patients were analyzed, and pleural indentation was observed in 258 patients (63.9%). All cancers turned out to be adenocarcinoma. Older age, worse lung function, longer diameter, and tumor shadow disappearance rate were associated with indentation. VPI was observed in 36 (8.9%) patients, and indentation was independently associated with VPI (odds ratio 9.34, p=0.032) after adjustment of pleural attachment, diameter, and tumor shadow disappearance rate. During a median follow-up duration of 48.3 months, 34 (8.4%) patients recurred. Although indentation was not associated with earlier recurrence (adjusted hazard ratio 2.16, p=0.168), concurrent pleural attachment with indentation was associated with recurrence among those with solid portion≥8mm (adjusted hazard ratio 3.05, p=0.019). Pleural indentation was associated with increased risk of VPI in GGO lung adenocarcinoma. Although indentation itself did not increase the risk of recurrence, concurrent pleural attachment with indentation may increase the risk of recurrence among selected patients.