Prognostic impact of the extracapsular lymph node involvement on disease-free survival according to the 7th edition of American Joint Committee on Cancer Staging System.

Objectives: The 7th edition of American Joint Committee on Cancer (AJCC) staging system of oesophageal cancer and gastro-oesophageal junction has re-staged positive nodes into N1-3 according to the number of invaded lymph nodes (LNs). However, this new classification does not consider the potential negative impact of the extracapsular breakthrough on survival. This study aims at assessing prognosis according to whether LN involvement is intracapsular (ICLNI) or extracapsular (ECLNI) on disease-free survival (DFS) among the three sub-groups of LN-positive patients.

Methods: Four hundred and sixteen consecutive R0 patients who underwent transthoracic oesophagectomy for cancer between 1996 and 2011 were retrospectively re-classified using the latest AJCC TNM classification. Among them, 230 (55%) patients have received a neoadjuvant chemoradiotherapy. Prognostic impact of ICLNI and ECLNI on DFS was assessed according to their new LN status. Multivariate analysis was drawn to determine factors affecting DFS.

Results: Among the 416 patients, there were 138 (33%) patients with positive LN: 79 (57%) with ICLNI and 59 (43%) with ECLNI. The proportion of ECLNI was 21 of 73 (28%), 21 of 41 (51%) and 17 of 24 (70%) in N1, N2 and N3 patients, respectively. In N1 patients, median DFS was 48 months in ICLNI and 13 months in ECLNI (P = 0.068). In N2 patients, median DFS was 19 months in ICLNI and 9 months in ECLNI (P = 0.07). In N3 patients, median DFS was not reached in ICLNI and was 6 months in ECLNI (P = 0.002). On multivariate analysis, the ECLNI (P < 0.001, hazard ratio, HR: 2.51) and the post-T stage (P = 0.03, HR: 1.62) were the two independent factors affecting DFS.

Conclusions: Based on our limited study population, the existence of an ECLNI seems to have an additive negative impact on DFS, regardless of the pN stage. This suggests that extracapsular breakthrough status should be added to the new TNM staging system. This information has to be validated by further investigations.