Prognostic Impact of Lymph Node Ratio in Obstructive Colorectal Cancer

Background: An estimated 15% to 20% of patients with colorectal cancers present with intestinal obstruction. Although colorectal cancer patients with lower lymph node ratios (LNR) have been shown to have a higher overall survival and disease free survival, this finding has not been clearly defined in patients with obstructive colorectal cancer. Here, we examine the impact of LNR on oncologic outcomes of colorectal cancer patients with and without obstruction. Methods: A total of 143 patients who underwent surgery for colorectal cancer at a single urban safety-net hospital were identified, retrospectively, from 1999-2009. These patients were divided into two groups: Group A, obstructive colorectal cancer (OC) (n=37) and Group B, non-obstructive colorectal cancer (NOC) (n=106). Clinicopathologic data were compared between the two groups including lymph node ratio (LNR) and overall survival. Results: Demographics such as age, sex, and race were similar between the OC and NOC cohorts. The location of obstructing colon cancers were more often found in the sigmoid colon (29.7%). Whereas, the location of non-obstructing colon cancers occurred more often in the cecum (48.1%). Overall 5-year survival was 47.1% for OC group and 52.5% for the NOC group. There was no difference in the total number of lymph nodes harvested or the average LNR between the two groups. In a multivariate analysis, sex, race, emergent operation, and tumor- node-metastasis (TNM) stage were adverse factors for survival. In a multivariate analysis, male sex was favorably predictive of overall survival while LNR was not. Conclusion: LNR is not predictive of overall survival when an adequate number of lymph nodes are harvested in the setting of obstructive colon cancer.