Macroscopic assessment of nodal metastasis is not reliable in colon cancer

Background Japanese surgeons have to macroscopically assess nodal metastasis from colon cancer according to the general rules established in Japan. Adjuvant therapy is sometimes started after macroscopic assessment of nodal metastasis. Macroscopic assessment, however, is difficult in many cases. Methods We evaluated the reliability of macroscopic assessment of nodal metastasis in colon cancer by (1) comparing the number of nodes picked up macroscopically with that of nodes recognized microscopically, and (2) by comparing the number of metastatic nodes found between macroscopic and microscopic examination. Results The number of nodes found during macroscopic examination was equal to that found in microscopic examination in only 52 of 206 cases (25%). Although 120 of 206 cases (58%) were judged macroscopically to have metastatic nodes, 61 had no metastatic nodes found microscopically. Sensitivity and specificity for the recognition of cases with nodal metastasis was 85.5% and 55.5%, respectively. The number of metastatic nodes in macroscopic examination was equal to that in microscopic examination in 90 cases (44%). Conclusion Because macroscopic assessment of nodal metastasis is not reliable, physicians should not rely on macroscopic assessment to indicate the need for further therapy, such as adjuvant chemotherapy. The recommendation for macroscopic assessment of nodal metastasis should be eliminated from the general rules in Japan.