Prognostic significance of the distribution of lymph node metastasis in rectal cancer after neoadjuvant chemoradiation

Background

This study aimed to evaluate the prognostic significance of lymph node distribution (LND) in rectal cancer after neoadjuvant chemoradiation.

Methods

A total of 519 patients with primary rectal cancer who underwent curative resection after neoadjuvant chemoradiation were included. LND was classified into four groups: LND0, no lymph node metastasis (368/519, 70.9%); LNDp, lymph node metastasis along the inferior mesenteric artery (proximal) (15/519, 2.9%); LNDm, lymph node metastasis at the mesorectum (109/519, 21.0%); and LNDpm, lymph node metastasis at both the proximal and mesorectal areas (27/519, 5.2%). Clinicopathologic characteristics were analyzed to identify independent prognostic factors.

Results

In patients with positive lymph nodes, LND showed superior discrimination for 3-year DFS (LNDp 67.7%, LNDm 48.9%, and LNDpm 26.8%, P = 0.003) and 3-year LRFS (LNDp 93.3%, LNDm 81.4%, and LNDpm 60.5%, P = 0.009) compared to ypN stage (3-year DFS, N1 47.8%, N2 40.0%, P = 0.184; 3-year LRFS, N1 79.4%, N2 75.2%, P = 0.527). On multivariate survival analysis, LND was an independent prognostic factor for LRFS (P = 0.030) in patients with positive lymph nodes.

Conclusions

LND may improve the prognostic value of the ypTNM staging system for patients with node-positive rectal cancer after neoadjuvant chemoradiation, particularly in terms of local recurrence.

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