Predictive Factors Affecting Survival in Stage II Colorectal Cancer: Is Lymph Node Harvesting Relevant?

PURPOSE: Lymph node status is important in colorectal cancer. Multiple studies indicate a relationship between the number of nodes harvested and survival. This is important in patients with stage II disease where the role of adjuvant therapy is unclear. This study sought to analyze the impact of lymph node harvest on survival in patients with stage II colorectal cancer. METHODS: The data of our hospital's colorectal tumor registry from 1997 to 2008 was reviewed. The records of 3534 patients of all stages were analyzed; of these patients, 913 patients with stage II colorectal cancer underwent curative resection. A univariate analysis estimated 5-year survival by Kaplan-Meier analysis based on various lymph node groupings. Patients were further analyzed with respect to sex, age, tumor grade, and tumor location. Multivariate linear regression analysis by the Cox proportional hazards model was performed using these variables to analyze survival relative to lymph node harvesting. RESULTS: Of 913 stage II patients, the mean age was 71 years and 48% were male. Univariate analysis of the number of lymph nodes harvested found that >= 24 nodes removed was a significant and independent factor for improved survival in stage II (P = .009) and >= 36 nodes in stage III cancers (P = .008). Cox proportional hazards ratios found male sex (P < .03) and poorly differentiated tumors (P < .015) to be negative independent risk factors for survival. Tumor location in the sigmoid was associated with improved survival (P < .02). CONCLUSION: Patients with stage II disease had an improved survival when >= 24 lymph nodes were harvested, and patients with stage III disease had improved survival with up to a 36 node harvest. Male sex and poorly differentiated tumors had a worse prognosis, and tumors located in the sigmoid were associated with improved survival in stage II cancers. An increased lymph node harvest is recommended to improve survival in these stages.