P2.02-017 A Clinical Outcome of Resected Small-Sized Non-Small Cell Lung Cancer 1 cm or Less in Diameter with N2 Lymph Node Metastasis

Abstract

The detection of small-sized (≤ 1cm) non-small cell lung cancer (NSCLC) has increased with the development of high-resolution computed tomography. The reported 5-year survival rate of T1a (≤ 2cm) N0M0 patients is more than 80%, and that of p-T1a (≤ 2cm) N2M0 patients has also steadily improved. Between 1991 and 2011, a total of 917 patients with small-sized (≤ 2cm) NSCLC underwent curative pulmonary resection with systematic lymph node dissection at Tokyo Medical University Hospital and Tokyo Medical University Ibaraki Medical Center. We retrospectively evaluated their postoperative clinical outcomes and survival rates. Survival was analyzed using the Kaplan-Meier method and log-rank test. There were 46 (5.0%) patients with mediastinal lymph node metastasis in pT1a (≤ 2cm). And there were 6 (0.6%) patients with pT1a (≤ 1cm) N2M0. The histological types were 3 cases of adenocarcinoma, 2 case of squamous cell carcinoma, and one large cell carcinoma. The respectively status of lymph node metastasis was single station in 2 cases and multiple station in 4 cases. Skip lymph node metastasis was observed in 2 cases. There were 26 cases (56.5%) that were upstaged from clinical diagnosis in pT1a (≤ 2 cm) N2M0 patients. There was one upstaging case from cT1a (≤ 1 cm) N0M0 to pT1a (≤ 2 cm) N2M0. The median overall survival period and 5-year survival of patients in pT1 (≤ 2 cm) N2M0 was 52.1 months and 45%. And patients with pT1a (≤ 1 cm) N2M0 has 29.8 months and 0% (3 year overall survival rate was 33.3%). The recurrence rate was 71.7% (5/6) and disease free survival was 13.2 months. This study showed that 5.0% of small-sized (≤ 2 cm) NSCLC had N2 disease and 0.6% of T1a (≤ 1 cm) NSCLC has pN2. Moreover, 56.5% of small-sized (≤ 2 cm) NSCLC was upstaged from clinical diagnosis to pathological diagnosis. The patients with pT1a (≤ 1 cm) N2M0 had worse survival data than the patients with pT1a (≤ 2 cm) N2M0. We recommend systematic lymph node dissection for local treatment as well as accurate diagnosis. As multiple mediastinal node metastases showed an unfavorable prognosis, surgery combined with systematic treatment is recommended.