The lymphatic infiltration identified by D2-40 monoclonal antibody predicts lymph node metastasis in submucosal invasive colorectal cancer.

BACKGROUND AND STUDY AIMS Lymphatic infiltration has been recognized as a significant risk factor for lymph node metastasis of submucosal invasive colorectal cancer (SICC), but it is difficult to detect microscopically on hematoxylin and eosin (H&E)-stained slides. We therefore identified lymphatic infiltration of tumor cells with D2-40 monoclonal antibody, which reacts specifically against the endothelium of lymphatic vessels, to make an objective and precise diagnosis. PATIENTS AND METHODS The surgical specimens of 122 consecutive patients with nonpedunculated SICC were examined for lymphatic infiltration by immunohistochemical staining with D2-40 monoclonal antibody (LI-D) and for venous infiltration by Elastica van Gieson staining (VI-E). RESULTS Lymph node metastasis was found in 20 patients. Multivariate analysis showed that LI-D (p = 0.0415) and VI-E (p = 0.0119) were significant risk factors for lymph node metastasis. Regardless of the presence of risk factors including at least either lymphatic infiltration or venous infiltration, no lymph node metastasis-positive patients were found (0%) among the 25 patients whose colorectal cancer had a submucosal invasive depth of less than 1,500 microm. No lymph node metastasis was found in any of the patients with a depth of submucosal invasion of less than 3,000 microm, who had no risk factors, including LI-D or VI-E. CONCLUSIONS Correct evaluation of lymphatic infiltration by immunohistochemical staining with D2-40 monoclonal antibody may play a crucial role in determining whether there are indications for additional treatment in the management of endoscopically resected SICC.