The Significance of Skip Lymph Node Metastasis in Colorectal Cancer

Background/Aim: The purpose of this study was to elucidate the status and clinical significance of skip lymph node metastasis (LNM) in colorectal cancer. Patients and Methods: This is a retrospective cohort study from a high-volume cancer center in Japan. A total of 1,060 patients with primary stage III colorectal cancer (CRC) underwent radical resection were included in the study and divided into skip LNM (LNM) (skip+) and non-skip LNM (skip-) groups. Propensity score matching was used to balance potential confounding factors. The cancer-specific survival (CSS) and relapse-free survival rate (RFS) between the two groups before and after matching were evaluated. Results: Before matching, patients in the skip+ group had a greater number of LNM (pN2: 48.3% vs. 31.1%; p<0.001), more pathological stage IIIC (43.2% vs. 17.6%; p<0.001), and a higher rate of recurrence (38.1% vs. 25.8%; p=0.0045). Consequently, the CSS (p=0.034) and RFS (p=0.005) were worse compared to the skip- group. However, after matching, there were no significant differences in prognosis for CSS (p=0.529) and RFS (p=0.515). In multivariate analysis, skip+ was not an independent risk factor for prognosis. However, the skip+ LNM group was more likely to have local lymph node recurrence. Conclusion: Skip+ LNM was more likely to happen in later stage CRCs, leading to significantly poorer survival outcomes. However, when all background factors were matched, the prognosis of the skip+ group was not worse. Surgeons need to be more alert to the possibility of local recurrence in patients with skip LNM.