Prognostic impact of lymph node skip metastasis in Stage III colorectal cancer

Aim The aim of this study was to evaluate the prognostic impact of lymph node skip metastasis ( LNSM ) in patients with Stage III colorectal cancer. Method Between April 2003 and December 2014, a total of 41 patients with lymph node skip metastasis (skip+) were compared with 86 patients with pericolic lymph node metastases [lymph node distribution ( LND )1] and 57 patients with intermediate and/or main lymph node metastasis ( LND 2+3). All patients had radical D3 lymphadenectomy, performed either laparoscopically or as open surgery. Results The frequency of pT 1–2 stage cancer was significantly higher in the skip+ group than in the LND 1 group (26.8% vs 5.8%, P  =   0.001). The number of metastatic lymph nodes in the skip+ group was lower than in the LND 2+3 group (1.9 ± 1.5 vs 6.5 ± 6.0, P  < 0.001). The 3‐year disease‐free survival ( DFS ) of the skip+, LND 1 and LND 2+3 groups was 64.8%, 69.7% and 40.1%, respectively ( P  =   0.008). The 3‐year systemic recurrence rates of the skip+, LND 1 and LND 2+3 groups were 30.2%, 20.3% and 48.1%, respectively; ( P  =   0.002). Cox regression analysis revealed that preoperative carcinoembryonic antigen ( CEA ) of ≥ 5 ng/ml [hazard ratio ( HR ) = 2.2, P  =   0.029], poor differentiation ( HR  = 3.8, P  =   0.001) and skip+ ( HR  = 0.2, P  =   0.021) were independently prognostic factors for DFS . Conclusion The prognosis for the LND1‐negative lymph node skip metastasis group was better than for the LND 2+3 group and was comparable with that of the LND 1 group after radical D3 lymphadenectomy.