P1.17-17 The Impact of Induction Chemoradiotherapy Followed by Surgery for N1 Involved Non-Small Cell Lung Cancer

Abstract

Induction chemoradiotherapy (iCRT) followed by surgery is usually selected for locally advanced non-small cell lung cancer (NSCLC) patients with mediastinal lymph node (LN) metastasis or invasion to adjacent organs, whereas it is occasionally performed for clinical N1 (cN1) NSCLC patients harboring such as a centrally located primary tumor or a bulky LN to improve local control rate and secure a cancer-free surgical margin. However, the survival benefit of iCRT followed by surgery for NSCLC patients with N1 LN involvement remains controversial. Furthermore, the accuracy of the radiological examination for N1 metastasis is unsatisfactory. In this study, we investigated the clinical outcomes of surgery with or without iCRT based on the estimation of the pretreatment LN metastatic status from fibrotic or necrotic changes of resected LNs in the cN1 NSCLC patients. cN1 NSCLC patients who underwent complete resection with or without iCRT at our institution between January 1999 and December 2016 were subjected. We divided the enrolled patients into two groups as the primary surgery (PS) group and the iCRT followed by surgery (IC) group. As for IC group, we determined the pretreatment LN metastatic status based on the pathological features of resected LNs. We compared the clinical outcomes of pretreatment N1 involved patients with or without iCRT. Among 127 cN1 NSCLC patients, 40 patients were considered as pretreatment N1 involvement, consisting of 26 and 14 patients in the PS and IC groups, respectively. The central type tumor and the continuous type of LN, which frequently required the extended surgical procedures, were significantly more frequent in the IC group than in the PS group (P < 0.01). Although there was no significant difference in the recurrence pattern between the two groups, none of patients developed local recurrence in the IC group. Regarding the patients with a centrally located tumor or a bulky LN (> 2.0cm), the 5-year recurrence-free survival was significantly better in the IC group than in the PS group (74.1% vs, 36.4%; P =0.03). Our study demonstrated that iCRT followed by surgery could suppress the disease recurrence in the N1-involved NSCLC patients especially for the patients harboring a centrally located tumor or bulky LNs at N1 level, suggesting that these patients may be good candidates for iCRT followed by surgery to avoid extended resections and to suppress the local recurrence.