P2.01-57 Prognostic Implication of Clinical, Imaging, and Pathologic Parameters in N2(+) Stage IIIA Lung Cancer Patients

As a comprehensive study of large scale and long-term clinical outcomes from a single institution, we are trying to analyze any predictive or prognostic factors for survival outcomes in N2(+) NSCLC patients. The purpose of this study is to investigate the efficacy of clinical, imaging (CT and PET-CT), and pathologic parameters, as a prognostic factor in N2(+) NSCLC patients undergoing tri-modality therapy. We retrospectively reviewed 160 patients with N2(+) NSCLC patients between January 2008 and June 2014. All patients underwent preoperative concurrent chemoradiotherapy (CCRT) (44-45 Gy in 22-25 fractions concurrent with weekly DP chemotherapy) and surgery. Clinical, imaging (CT and PET-CT), and pathologic parameters were analyzed with respects to outcomes. Overall pathologic down-staging and pathologic complete response following preoperative CCRT were achieved in 66 (41.3%) and 13 patients (8.1%), respectively. The median follow-up durations of all patients was 43 months (2∼106 months). The 5-year rates of disease-free survival (DFS) and overall survival (OS) were 33.3% and 53.0%, respectively. Pathologic N down-staging (HR 2.604; 95% CI 1.418-4.779; p value=0.002) was a significant factor for DFS. Histopathology (HR 0.475; 95% CI 0.242-0.930; p =0.030), GTV of nodal lesion(s) on pre-RT CT (HR 1.066; 95% CI 1.029-1.104; p <0.001), type of surgery (HR 2.985; 95% CI 1.114-7.997; p =0.030), and proportion of viable tumor on cross-section area (HR 0.986; 95% CI 0.973-0.999; p =0.034) were significant factors for OS. Neither tumor volume reduction rate (TVRR) nor SUVmax was significant for DFS or OS. In patients with N2(+) NSCLC undergoing tri-modality therapy, we proved that none of the imaging parameters correlated with prognosis, except pretreatment nodal volume. We confirmed that patients with adenocarcinoma showed prominently improved survival and pathologic N down-staging was a most important pathologic parameter as a prognosticator.