RADIOIMMUNOGUIDED SURGERY AFTER PRIMARY-TREATMENT OF LOCALLY ADVANCEDBREAST-CANCER

Purpose: To assess the role of radioimmunoguided surgery (RIGS) using a handheld intraoperative gamma-detecting probe (GDP) to identify neop lastic disease after primary chemotherapy in locally advanced breast c ancer (LABC) patients injected with iodine 125-labeled monoclonal anti bodies (MAbs). Patients and Methods: Twenty-one patients with histolog ically; were treated with a combined modality approach. After three co urses of primary chemotherapy and before modified radical mastectomy, the I-125-radiolabeled MAbs B72.3 (anti-TAG72) and FO23C5 (anticarcino embryonic antigen [CEA]) were administered to 11 patients (group A) an d 10 patients (group B), respectively. At surgery, a GDP was used to l ocate the primary tumor and to assess possible tumor multicentricity a nd the presence of ipsilateral axillary metastases. Routine pathologic examination was performed in neoplastic and normal tissue specimens o f all 21 patients, In addition, immunohistochemical assay for TAG72 an d CEA expression wets performed. Results: In group A patients, RIGS id entified primary tumor in seven of 11 patients (63.3%) and unpalpable multicentric tumor lesions were located in two of four (50%). Positive axillary lymph nodes were histologically documented in eight of 11 pa tients (72.7%) and RIGS identified three of eight (37.5%). In group B, RIGS located the primary tumor lesion in four of 10 patients (40%); i n two cases, the tumor was not clinically evident, Multicentricity was observed in one of two patients and lymph node involvement in three o f nine (33.3%), No false-positive results were observed in either grou p A or B. Conclusion: RIGS appears to be a safe and reliable technique . However, the MAbs used in this study are not sufficiently specific. RIGS represents a technique for which the full potential for intraoper ative assessment of breast cancer lesions can be reached when more spe cific antibodies become readily available. (C) 1996 by American Societ y of Clinical Oncology.