Immunolymphscintigraphy of axillary lymph node metastases in breast cancer patients using monoclonal antibodies: first clinical findings.

The results of preliminary investigations into the immunolymphscintigraphic (ILS) detection of axillary lymph node metastases in nine breast cancer patients by means of the 3C6F9 monoclonal antibody (MAs) are presented. The IgG2a monoclonal antibody detects a 37 KD antigen, consistently found on the surface of primary and metastatic breast tumors. Each patient received 1 mCi of I-123 (specific activity, 2 mCi per mg of antibody) as a subcutaneous injection between the 2nd and the 3rd finger of both hands, i.e., the healthy side serving as a control for the affected side. Clear images of lymph node metastases were visible 4 to 8 hours after injection of the antibody. Seven of the nine patients studied were positive by scanning and six showed positive lymph node involvement by histopathology (6/7; true positive = 86%). Two patients did not show any iodine uptake in the axilla and were subsequently found to be free of metastases (2/2; true negative = 100%). These data give an overall accuracy of ILS of 89% and demonstrate that 3C6F9 localizes preferentially in affected axillary lymph nodes compared to normal lymph nodes.