Radioimmunoguided surgery after primary treatment of locally advanced breast cancer.

Abstract PURPOSE: To assess the role of radioimmunoguided surgery (RIGS) using a handheld intraoperative gamma-detecting probe (GDP) to identify neoplastic disease after primary chemotherapy in locally advanced breast cancer (LABC) patients injected with iodine 125-labeled monoclonal antibodies (MAbs). PATIENTS AND METHODS: Twenty-one patients with histologically documented LABC were treated with a combined modality approach. After three courses of primary chemotherapy and before modified radical mastectomy, the 125I-radiolabeled MAbs B72.3 (anti-TAG72) and FO23C5 (anti-carcinoembryonic antigen [CEA]) were administered to 11 patients (group A) and 10 patients (group B), respectively. At surgery, a GDP was used to locate the primary tumor and to assess possible tumor multicentricity and the presence of ipsilateral axillary metastases. Routine pathologic examination was performed in neoplastic and normal tissue specimens of all 21 patients. In addition, immunohistochemical assay for TAG72 and CEA expression was performed. RESULTS: In group A patients, RIGS identified 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 patients (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%); in two cases, the tumor was not clinically evident. Multicentricity was observed in one of two patients and lymph node involvement in three of nine (33.3%). No false-positive results were observed in either group 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 intraoperative assessment of breast cancer lesions can be reached when more specific antibodies become readily available.