Pre-operative assessment of axillary lymph node status in patients with breast adenocarcinoma using intravenous 99mtechnetium mAb-170H.82 (Tru-Scint AD)

Abstract

Immunoscintigraphy of the axilla has potential utility for the diagnostic and prognostic assessment of patients with breast adenocarcinoma. mAb-170H.82 is a murine monoclonal antibody (mAb) derived against synthetic Thomsen-Friedenreich (TF) antigen. Tru-Scint AD, a 99mTc-mAb-170H.82 immunoconjugate, has previously been shown to localize in various human adenocarcinomas. The purpose of this study was to evaluate the accuracy of this immunoconjugate in the pre-operative assessment of axillary lymph nodes in patients with known breast adenocarcinoma. Sixteen patients with documented primary breast cancer were injected intravenously with 1 mg of immunoconjugate (radioactivity 1.8 GBq) and imaged 22-24 hrs post-injection. Both planar and single photon emission computed tomographic (SPECT) images were obtained and reviewed in a blinded fashion. Imaging results were compared with surgical and pathological findings. Seven of 16 patients were found to have histologically positive axillary nodes: 5 of these sites were detected by immunoscintigraphy (sensitivity = 71%). Nine patients had pathologically disease-free axillary nodes: only 1 of these was misidentified as positive by immunoscintigraphy (specificity = 89%). These results suggest that immunoscintigraphy with 99mTc-mAb-170H.82 has promise in the detection of axillary lymph node involvement in patients with breast cancer. Further studies are warranted to define the role of immunoscintigraphy in axillary staging.