O5. Prognostic significance of clinical T2aN0M0 GGO—dominant lung adenocarcinoma

Background: Recent studies have demonstrated that ground glass opacity (GGO)-dominant tumors on high-resolution computed tomography (HRCT) correspond to a pathologically low-grade adenocarcinoma and patients with resected those tumors have excellent prognoses. However, almost those study objects were limited to the tumors which size was ≤3.0 cm. The purpose of this study was to characterize lung adenocarcinomas >3.0 cm in diameter with GGO-dominant feature on HRCT, and evaluate the prognoses of patients with those tumors after surgical resection.

Methods: One hundred and thirteen patients with clinical T2aN0M0 lung adenocarcinoma underwent surgical resection after HRCT scanning between 2005 and 2011. Among them, 25 patients had a tumor with ≥50% GGO component on HRCT (GGO-dominant group), and the remaining 88 had a solid-dominant tumor (Solid-dominant group). Clinicopathologic findings and prognoses of the two groups were evaluated.

Results: Tumors of the GGO-dominant group rarely exhibited pathologic invasiveness including lymphatic (n=1), vascular (n=0), and pleural invasions (n=5) and lymph node metastasis (n=0). On the other hand, tumors of the solid-dominant group frequently exhibited pathologic invasiveness; lymphatic (n=26), vascular (n=16), and plural invasions (n=52) and lymph node metastasis (n=18). Between the two groups, there were significant differences in all of the characteristics of pathologic invasiveness (lymphatic; P=0.0026, vascular; P=0.0214, and pleural invasion; P=0.0004, and lymph node metastases; P=0.0086, respectively). In the GGO-dominant group, 24 patients were alive without recurrence, and the remaining one who also had no recurrence was dead of other cancer. Meanwhile, recurrences occurred in 34 patients of the solid-dominant group, and 16 were dead of disease. The 5-year survival rate was 96% in the GGO-dominant group, while that was 71% in the solid-dominant group (P=0.0120).

Conclusions: In the GGO-dominant group, malignant potential of the adenocarcinomas exhibited low-grade, and the patients had an extremely favorable prognosis after anatomical resection of the clinical T2aN0M0 tumor, as same as patients with GGO-dominant tumor diagnosed as clinical T1a-bN0M0.

Keywords: Prognosis; adenocarcinoma; early stage; non-small cell lung carcinoma (NSCLC)