Non-BAC Component but not Epidermal Growth Factor Receptor Gene Mutation is Associated with Poor Outcomes in Small Adenocarcinoma of the Lung

Abstract

ObjectiveThe purpose of this study was to identify risk factors for poor clinical outcome after surgical resection of small lung adenocarcinoma.Materials and MethodsClinical records of 127 patients who had pathologic stage IA lung adenocarcinoma 20 mm or less and who had undergone a lobectomy with mediastinal lymph node dissection were reviewed. The percentage of non-bronchioloalveolar carcinoma (non-BAC) components quantified objectively, and epidermal growth factor receptor gene (EGFR) mutation determined by polymerase chain reaction-based assay were retrospectively linked with clinical data.ResultsBased on the percentage of non-BAC component, 127 patients were classified as follows: 26 in group I, BAC, 46 in group II mixed subtype with ≥ 50% BAC, 18 in group III, mixed subtype with under 50% BAC, and 37 in group IV, mixed subtype with all non-BAC components or a pure pattern of one of the non-BAC components. Groups I and II were considered to be a “low non-BAC component type” and groups III and IV were considered to be a “high non-BAC component type.” EGFR mutations in exon19 and exon21 were observed in 64 patients (50.4%). In terms of recurrence, the high non-BAC component type was the only independent factor for recurrence (p = 0.029). Regarding survival, the high age (p = 0.028) and high non-BAC component type (p = 0.046) were independent risk factors for poor overall survival. They were also independent risk factors for poor disease-free survival (p = 0.025 and p = 0.027, respectively).ConclusionThe high non-BAC component but not EGFR mutation status, is an independent risk factor for both recurrence and poor prognosis in patients with stage IA lung adenocarcinoma ≤20 mm