Impact of Tumor Site on Lymph Node Status and Survival in Colon Cancer

Objective Our objective was to explore the impact of tumor sites on lymph node (LN) status and prognosis in non-distant metastasis colon cancer after radical operation. Methods Surveillance, epidemiology, and end results (SEER) database was used to identify 124, 836 early-stage colon cancer patients between 1988 and 2010, treated with radical surgery with a known tumor site. Seven tumor sites were defined as ascending, hepatic, cecum, transverse, descending, splenic, and sigmoid colons by the anatomical location. The associations of tumor site and LN status, including adequate (≥12) LN harvest and LN positivity, were examined with logistic regression, adjusting for multiple covariates. Relative survival was compared in a flexible parametric model. Results The quartile number of LN examined gradually decreased from ascending to sigmoid colon cancer (P<0.001 for all patients, and T2, T3 and T4 stages). More numbers of LN examined and a higher proportion of LN positivity were retrieved in left-half colon cancer than in right-half colon cancer. Cumulative incidence of death (CID) was higher in patients with less LN examined except for the group of cecum colon cancer, but there was no significant difference between all groups (5-year CID: 18.99%~21.98% for LN count ≥ 12 and 23.01%~26.89% for LN count <12). Conclusions LN examined and LN positivity in colon cancer were important prognostic factors. There was no significant CDI difference between groups with different tumor sites. Current guidelines for extent of resection should take this into consideration so that and unnecessary treatment may be avoided.