The correlation between the number of lymph nodes identified and treatment outcomes in colorectal cancer patients: Single-institution experience.

Abstract

e14096 Background: Colorectal cancer is the third leading cause of cancer-related death in the Western world. International guidelines recommend evaluating at least 12 locoregional lymph nodes (LNs) on curative surgery to obtain optimal staging information and satisfactory long-term outcomes. In the United States, adequate number of LN identified is achieved in 37% of cases. This study aimed to evaluate the impact of LN status on survival rates in colorectal cancer patients in a single institution setting. Methods: We analyzed data on all patients undergoing radical surgery for colorectal cancer in the Bon Secours Hospital Cork in Ireland between years 2000 and 2006. Numbers of LN identified and number of LN infiltrated were recorded. The lymph node ratio (LNR) was calculated using following formula: LNR = LN infiltrated/LN identified. Overall survival (OS) was used as a primary endpoint. Multivariate analyses were performed on all patients and on following LNR groups: LNR < 0.05, 0.05-0.19, 0.2-0.39, and 0.4-1.0. Covariates included were age, sex, tumor grade, tumor location, lymphovascular and perineural invasion. Results: In total 265 patients were included in this study. The median age was 66 years (range 34 to 89). One hundred and thirty-three patients (50.2%) had 11 or less LNs examined, and 132 patients (49.8%) had 12 or more LNs examined. Mean OS was 73 months for all patients. Patients in the Dukes C2 category (> 3 LN infiltrated and/or tumour infiltrating adjacent structure) who had 12 or more LNs identified had a better OS compared to those who had 11 or less LNs investigated (hazard ratio 0.677 [95%CI 0.45-1.01]). Patients in all Dukes categoreis who had a lower LNR had a significantly better OS than those with a higher LNR (p < 0.0001). Conclusions: Nearly 50% of patients with colorectal cancer undergoing radical surgery had 12 or more lymph nodes investigated. A higher number of LN identified was associated with better survival in the Dukes C2 category. A higher number of LN infiltrated was associated with shorter survival. No significant financial relationships to disclose.