The significance of intraoperative periportal lymph node metastasis identification in patients with colorectal carcinoma

Background. Nine patients who underwent Radioimmunoguided Surgery (RIGS) (Neoprobe Corporation, Dublin, OH) procedures for colorectal cancer were found to have disease recurrence in the periportal area. This led to a retrospective study to determine whether periportal lymph node involvement could have been predicted intraoperatively for these patients. Methods. One hundred twenty‐four patients underwent second‐look RIGS for recurrent colon and rectal cancer from 1986 to 1992. The monoclonal antibody (MAb) B72.3 was administered as the carrier agent to 87 patients and the CC49 second‐generation MAb was administered to 37 patients. Both MAbs were radiolabeled with Iodine‐125. Results. Periportal lymph nodes with RIGS‐positive tissue were found in 47 (38%) patients, hematoxylin and eosin‐positive lymph nodes were found in 13 of 47, and in further immunohistochemical studies performed for 31 of the remaining 34 patients, positive lymph nodes were found in 8, resulting in an incidence of 48% (21/44). A critical review of the nine patients' charts who later presented with a tumor mass in the periportal area demonstrated intraoperative gamma‐detecting probe counts in ratios three to five times that of the normal adjacent tissues in the periportal area at the time of first exploration. Probe‐directed biopsy was reported to be histologically negative for tumor in these patients, and, thus, the surgeon proceeded assuming the periportal area to be negative. A retrospective study of the periportal lymph nodes of these patients using cytokeratin immunohistochemical analysis identified tumor in five (56%). Conclusions. These findings suggest that the RIGS system may be a valuable method of intraoperative prediction and detection of periportal lymph node metastasis. Cancer 1995;75:2809–17.