Purpose: Patterns of metastatic spread are difficult to determine with routine postoperative follow-up. This study was undertaken to evaluate two selected populations of colorectal cancer patients injected and screened with anti-tumor antibody.
Methods: Eighty-six evaluable patients with colorectal cancer underwent exploratory laparotomy with both traditional surgical exploration and radioimmunoguided surgery (RIGS) following injection of 125I-labeled CC49 monoclonal antibody. RIGS-positive tissue detectable with a handheld gamma-detecting probe was defined as tissue involved with the disease process. Comparisons were made between extent of disease using traditional exploration and extent using RIGS.
Results: In 41 patients with primary disease, traditional exploration detected 45 sites of disease (1.1 sites/patient) compared with 153 RIGS-positive sites (3.7 sites/patient). In 45 patients with recurrent disease, traditional exploration found 116 sites (2.6 sites/patient) vs. 184 RIGS-positive sites (4.1 sites/patient). Involvement by selected anatomic sites is shown below [Table: see text].
Conclusion: RIGS detected more tissue involved in disease process for all sites in both primary and recurrent disease except liver metastases. Areas with highest proportion of RIGS-positive tissue, the gastrohepatic ligament and celiac nodes, are rarely resected and are not pathologically examined. Positive RIGS localization of tumor antigen in these areas suggests more extensive dissemination of disease process.