Lung Cancer with Localized Ground-Glass Attenuation Represents Early-Stage Adenocarcinoma in Nonsmokers

BackgroundStudies of lung cancer showing localized ground-glass attenuation (GGA) on thin-section computed tomography (TSCT) have been limited to resected stage IA adenocarcinomas. This study aimed to clarify the features of localized GGA cancer as a distinct clinicoradiological entity through a survey of lung cancers of all types.MethodsFrom 2000 through 2002, 492 patients with newly diagnosed stage I–IV lung cancer underwent TSCT at a single institution. The tumors were semiquantitatively classified into four groups on the basis of GGA area as a percentage of the whole tumor shadow (GGA ratio) on TSCT images: 100%, 99–50%, 49–1%, and 0%. The relationship between clinicopathological data and the GGA ratio, predictors of the presence of GGA, survival data, and prognostic factors were evaluated retrospectively.ResultsAll localized GGA cancers were adenocarcinomas (p < 0.05). A GGA component was not found in patients with advanced cancer (p < 0.05). GGA cancer was related to nonsmoking status (Odds ratio 6.17, p < 0.05). A threshold tumor size of 30 mm in GGA cancer (hazard ratio, 2.86; p < 0.01) and the GGA ratio (hazard ratio, 4.17; p < 0.01) were independent prognostic factors. Survival rates were higher in patients with a GGA ratio ≥50% and stage IB lung cancer than in patients with a GGA ratio <50% and stage IA lung cancer.ConclusionLocalized GGA cancer, with presurgical prognostic factors of tumor size and GGA ratio, represents early-stage lung adenocarcinoma in nonsmokers.