GGN (Ground-glass opacity nodule) is defined as rounded areas of homogeneous or heterogeneous increased attenuation in computed tomography (CT) scans, which are lower in density with regard to surrounding soft tissue structures, such as vessels, that is generally associated with the early-stage lung adenocarcinoma (Lee et al 2011). Therefore, some insist that the malignancy-favored GGO should be called GGN. Multiple pure GGO lesions detected in patients undergoing pulmonary resection for lung adenocarcinoma have a high possibility of malignancy if the size is greater than 7.5 mm. (Kim et al 2009) Nowadays, GGNs of the lung are increasingly detected with thin-section CT scan. GGNs are categorized as pure GGNs and mixed GGNs according to the images from a high-resolution CT.~Usually, lung adenocarcinoma with synchronous GGNs is considered a distinct disease entity in multiple synchronous lung cancers. Few studies have performed next-generation sequencing analysis of these synchronous sequential lesions. Recent study shows that multiple synchronous lesions in the same patient showed different mutation profiles (Park et al 2018) That suggests that adenocarcinoma and synchronous GGNs are genetically independent tumor. But interestingly, driver gene mutations were homogeneously distributed. These findings support the relevance of molecular characterization of lung adenocarcinoma and accompanying GGNs.~The development of a standardized approach to the interpretation and management of GGNs remain critically important given that peripheral adenocarcinomas represent the most common type of lung cancer, with evidence of increasing frequency.~The surgical management of patients with remaining GGN(s) who underwent surgery for the main tumor is still controversial. Although surgical approaches for the remaining lesions depend on their anatomical location, size, and number, as well as the patient's age and pulmonary function, the decision usually depends on the surgeon's judgment; no standard criteria have been established for the selection of the lesions to be treated, nor the method of management of the residual nodules in cases of resectable lung adenocarcinoma with synchronous GGNs. If GGNs are located deep in the hilum or scattered in different lobes or contralateral lung, they cannot be resected simultaneously so that may require additional surgery or radiation therapy. Investiators hypothesized that, in patients with confirmed EGFR mutation positive disease, postoperative osimertinib may regress synchronous GGNs, and eventually, avoid the need of repeated surgery. The purpose of this study is to confirm the efficacy and safety of osimertinib to regress synchronous GGNs in other lobes by osimertinib for stage IB-IIIA adenocarcinoma after curative resection.
This is an open label, phase II study to assess the efficacy of osimertinib (80 mg, orally, once daily) to suppress the progression of remaining GGN(s) in other lobes following surgical resection for actionable EGFR mutation-positive stage IB-IIIA lung adenocarcinoma.