The role of apical lymph node metastasis in right colon cancer

Background The role of apical lymph node (APN) metastasis in colorectal cancer remains controversial. The main purpose of this study is to explore the prognostic value of APN metastasis in patients with right colon cancer. Methods This is a retrospective study of patients with stage III right colon cancer between April 2007 and December 2016. Patients who underwent resection of right colon cancers with D3 lymph node dissection were divided into APN-positive (APN+) and APN-negative (APN-) groups according to the postoperative pathological presence or absence of APN metastasis. Relapse-free survival (RFS) and overall survival (OS) between groups were compared after Cox regression analysis and 1:1 propensity score matching (PSM). Results A total of 254 patients were included in this study: 28 (11.0%) were APN+ and 226 (89.0%) were APN-. Before matching, the rates of elevated carcinoembryonic antigen (CEA), T3-4 tumor invasion, and N2 lymph node metastasis were significantly higher in the APN+ group (CEA >= 5 ng/mL, 53.6% vs. 37.6%, p < 0.001; T3-4, 92.9% vs. 85.4%, p < 0.001; N2 metastasis, 57.1% vs. 20.4%, p < 0.001), and APN+ tumors were associated with significantly higher postoperative relapse rates (39.3% vs. 21.2%; p = 0.03), especially with lung metastases (14.3% vs. 4.0%; p = 0.019), which conferred worse RFS (p = 0.013), although OS was similar (p = 0.078). However, after PSM, there were no apparent between-group differences in RFS (p = 0.29) or overall survival rate (p = 0.637). The Cox regression analysis indicated that lymphatic vessel infiltration and depth of invasion were independent risk factors for OS, while APN+ status was not a significant predictor for RFS or OS. Conclusions APN metastasis was not a prognostic indicator for RFS or OS in right colon cancer. However, APN+ patients with elevated CEA levels and deeper tumor invasion should be closely monitored for lung metastasis during postoperative follow-up.