P2.02-033 The Role of Surgery for Treating Occult N2 Non-Small Cell Lung Cancer

Abstract

The presence of mediastinal nodal metastasis is one of the most important factors in the treatment of non-small cell lung cancer (NSCLC). The role of surgical intervention for treating N2 disease is controversial, and two randomized trials failed to show an overall survival benefit. Consequently, the purpose here is to elucidate the needs for surgical intervention of resectable N2 NSCLC. Between April 2010 and May 2016, 316 patients with NSCLC underwent pulmonary resection and mediastinal lymph node dissection. Patients with pathologic N2 were 26. Clinical outcomes and risk factors for pathologic N2 disease were retrospectively analyzed for this cohort. Surgical treatment was performed of 26 pathologic N2 disease patients; there were 18 men and 8 women with a mean age of 68.3 years old (range 55-84). Occult pathologic N2 disease was identified in 22 patients (84.6%). The most common type of resection was lobectomy (96.1%). Adjuvant chemotherapy was administered in 21 patients (80.8%). N2 involvement was single-station in 4 (15.4%) and multiple-station in 22 (84.6%). All patients recovered and were discharged home. There was no operative mortality, and no hospital deaths. The 5-year overall and disease-free survival rates were 58.6% and 33.4%, respectively. The 5-year survival rates of single-station and multiple-station N2 were 50% and 73.2%, respectively (p =0.92). Patients with clinical (expected) N2 disease exhibited better survival outcomes compared with those with occult N2 disease (100% vs 59.8%). The group receiving adjuvant chemotherapy had significantly higher the 5-year survival rates. The 5-year survival rate in patients who received 4 or more cycles of adjuvant chemotherapy was 78.1%, as compared with 0% in non-treated patients (p =0.0008). The 5-year overall and disease-free survival rates of N2 disease tend to improve in recent years. The reasons for improved survival are the increasingly successful treatment options for recurrent disease, including chemotherapy, radiotherapy, and/or molecular targeting drugs. It is common knowledge that therapy of N2 disease needs not only surgery but also chemotherapy. The multiple courses of adjuvant chemotherapy may further improve the outcome in N2 disease. However, patients treated with surgery and chemotherapy had significantly better the 5-year survival rates than patients treated with chemotherapy alone. Though surgery might be very important in that way, the role of surgery for treating N2 disease remains an open question. Because we acknowledge that as a single-institution and retrospective analysis, our sample size was limited. We consider that large-scale, multicenter clinical trials are needed.