The prognosis of invasive adenocarcinoma presenting as groundglass opacity on chest computed tomography after sublobar resection

Background: Ground-glass opacity (GGO) on chest computed tomography (CT) is generally associated with non-invasive or minimally invasive adenocarcinoma (MIA). However, many instances of GGO are diagnosed as invasive adenocarcinoma. The purpose of this study is to analyse the histopathologic characteristics of invasive adenocarcinoma presenting as GGO and the prognosis after sublobar resection. Methods: We conducted a retrospective chart review of 191 patients who were treated for stage I nonsmall cell lung cancer presenting as a GGO-predominant tumour upon CT and who underwent curative resection. We analysed the histologic subtypes and components of invasive adenocarcinomas presenting as GGO-predominant tumours. We also compared the 5-year recurrence-free survival (RFS) of invasive adenocarcinomas presenting as GGO-predominant in patients undergoing sublobar resection or lobectomy. Results: Of 191 GGO-predominant tumour patients, 97 patients had adenocarcinoma in situ (AIS) or MIA, and 94 patients had invasive adenocarcinoma. In the analysis of the histologic component of invasive adenocarcinoma presenting as GGO, the mean rate of the lepidic component was 47.4%, that of the acinar component was 42.1%, and that of the papillary component was 7.3%. Micropapillary and solid components were nearly absent. The 5-year RFS rates of sublobar resection and lobectomy were both 100%. Conclusions: Invasive components such as acinar and papillary components can also be seen as GGO tumours on chest CT. After the sublobar resection of GGO-predominant tumours, a good prognosis can be expected, even if the tumour is an invasive adenocarcinoma such as the acinar or papillary subtypes.