Tumor volume and percent positive lymph nodes as a predictor of 5-year survival in colorectal cancer

Background: Survival with stage III colorectal cancer (CRC) is variable and difficult to predict. Tumor size is not part of the staging system for CRC and in itself is not a predictor of survival. We hypothesize, however, that tumor size is important in determining disease free survival. Methods: Patients with stage III CRC were identified and divided into 2 categories: those who developed metastatic disease within 5 years after surgery and those who were alive and disease free at 5 years. A ratio of tumor volume to percent positive nodes was calculated for each patient (TN ratio). Results: Sixty-three patients were identified. 35 (55%) were alive and tumor free at 5 years. The TN ratio was significantly higher in patients who were disease free. Compared to number of positive nodes, percent positive nodes, and tumor volume, the TN ratio was the most significant predictor of disease free survival at 5 years. Conclusion: Patients who survive 5 years after CRC surgery have a statistically significantly higher TN ratio than those patients who have metastatic disease within 5 years. Patients with small tumors and positive nodes have a lower TN ratio and a statistically decreased 5-year survival.