Analysis of new N-category on prognosis of oesophageal cancer with positive lymph nodes in a Chinese population

Abstract

Abstract Background. The 7th edition of the new TNM classification system for oesophageal cancer (EC) has been published. N-category is now divided into N0, N1, N2 and N3. In this study, we aimed to validate the prognostic ability of the new N classification system in EC with positive lymph nodes in a Chinese population, and evaluate whether the new N classification system can help the decision-making for postoperative adjuvant therapy. Patients and methods. From 2002 to 2008, thoracic EC who underwent oesophagectomy were retrospectively analysed. Patients pathological stage 6th edition of the American Joint Committee on Cancer / Union International Against Cancer (AJCC/UICC) TNM classification were switched to pathological stage 7th edition for this analysis. Patients with pathological stage T1-4N1-3M0 EC were selected. Kaplan-Meier method and Cox regression analysis were employed to compare overall survival (OS). Results. A total of 545 patients met the inclusion criteria: 346 (63.5%) received oesophagectomy alone, 199 (36.5%) received oesophagectomy and adjuvant radiotherapy, and 36.1% (197/545) received oesophagectomy and adjuvant chemotherapy. Univariate analysis and multivariate analysis revealed significant difference in OS among patients at different postoperative pN-category (p<0.001). This was also present in patients receiving postoperative radiotherapy (p<0.001) and those undergoing postoperative chemotherapy (p<0.001). There was no marked difference in OS between patients receiving postoperative adjuvant therapy and surgery alone at the same postoperative pN-category, except that postoperative radiotherapy marginally improved OS in patients with pN2 and pN3 disease. Conclusions. Our results validated the prognostic ability of new N classification system. The N-category is an independent prognostic factor in patients with resectable thoracic EC who were positive for lymph nodes in a Chinese population. Further studies are required to clarify the role of new N classification system in the decision-making for postoperative adjuvant therapy.