Volume of Lymphatic Metastases Does Not Independently Influence Prognosis in Colorectal Cancer

PURPOSE: To evaluate the prognostic relevance of the volume of nodal metastatic disease in colorectal cancer patients. PATIENTS AND METHODS: One hundred node-positive patients with T2 or T3 carcinoma of the colon or rectum after routine histologic examination of the regional nodes were studied. The metastatic tumor was measured with an ocular micrometer, and the tumor volume was determined. RESULTS: The mean lymph node metastatic tumor volume was 5.1 ± 4.99 mm3 (range, 0.05 to 83,434 mm3). There was only a weak positive correlation with number of nodes involved with metastatic disease and tumor volume in nodes (r = .45). Median follow-up was 39 months (range, 1 to 87 months). The number of nodes was highly predictive of outcome. Individuals with one to three positive nodes had a substantially better survival than individuals with four or more positive nodes (P < .001). The volume of nodal metastatic disease correlated with outcome (P = .019). Patients dying as a result of disease had substantially greater mean metastatic nodal volume than those who were alive (3,705 v 1,783 mm3; P = .036). However, the total metastatic nodal volume did not, independent of positive nodes or number of positive nodes, predict outcome. Individuals with micrometastatic nodal volume did not have improved survival when compared with individuals with macrometastatic nodal volume (P = .79). CONCLUSION: The number of nodes involved with metastatic tumor, rather the volume of metastatic involvement of the regional lymph nodes, predicts outcome. These results suggest that micrometastatic disease may have a similar prognosis as macrometastatic disease when the same number of lymph nodes are involved with metastatic tumor.