Clinical significance of skip metastasis in patients with gastric cancer

Background Metastasis appearing to bypass or skip tiers of lymph nodes (LNs) has been referred to as skip metastasis. The clinical impact of skip metastasis in gastric cancer remains unclear. Methods In patients with gastric cancer, the clinicopathological features and postoperative prognoses of 21 patients with skip metastasis were evaluated and compared with findings in patients with group 1 (N1) or group 2 (N2) LN metastasis. Results Of the 21 patients with skip metastasis, 9 patients had metastasis in the LN along the common hepatic artery (No. 8a), 8 patients had metastasis in the LN along the left gastric artery (No. 7), 2 patients had metastasis in LNs No. 7 and No. 8a, 1 patient had metastasis in the LN at the splenic hilum (No. 10), and 1 patient had metastasis in LN No. 10 and the LN along the splenic artery (No. 11). The mean diameter of the tumors in the patients with skip metastasis was 5.7 ± 2.4 cm, which was significantly smaller than those in the N1 patients (7.9 ± 4.1 cm) and N2 patients (9.3 ± 4.6 cm). The incidence of serosal invasion, lymphatic vessel invasion, and peritoneal metastasis was lower in patients with skip metastasis compared with N2 patients. The 5-year survival rates were 70.2%, 62.0%, and 31.2% in patients with skip metastasis, patients with metastasis in group 1 LNs, and those with metastasis in group 2 LNs, respectively. The prognosis of patients with metastasis in group 2 LNs was significantly worse than that of patients with either skip metastasis (P = 0.0029) or metastasis in group 1 LNs (P < 0.0001). Conclusion Our data indicate that both the clinicopathological characteristics and the prognoses of patients with skip metastasis were similar to those of patients with N1 LN metastasis, but these features were not similar to those in patients with N2 LN metastasis. The sites of skip metastasis presented in the current study may be the key for applying the concept of the sentinel node in gastric cancer.