Use of radioimmunoguided surgery after induction chemotherapy in locally advanced breast cancer.

Twenty-one patients with histologically proven locally advanced breast cancer (LABC) were treated with a combined modality approach based on primary chemotherapy and radical modified mastectomy followed by adjuvant chemotherapy. Surgery was performed by using radioimmunoguided surgery (RIGS) technique with the preoperative injection of Iodine-125 labeled monoclonal antibodies (MoAbs) B72.3 anti-TAG (11 patients, Group A) and FO23C5 anti-carcinoembryonic antigen (CEA; 10 patients, Group B). The role of RIGS was defined at surgery by using an intraoperative hand-held gamma-detecting probe (GDP) to locate the primary tumor, possible clinically occult multicentric foci and ipsilateral lymph node metastases. In Group A, RIGS correctly defined the primary tumor in seven out of 11 patients (63.3%) and was able to find multicentric tumors in two out of four patients (50%). Positive lymph nodes were identified by RIGS in three out of eight patients (37.5%). In Group B, patients RIGS correctly located the primary in 4/10 cases (40%); in two RIGS-positive cases, the tumor was clinically not evident after primary chemotherapy (yT0). RIGS correctly identified multicentric foci of tumor in one out of two cases (50%). Correct lymph nodal RIGS assessment was observed in three out of nine patients (33.3%). No RIGS false-positive findings occurred in the 21 patients included in the study. RIGS appears to be a reliable technique for the intraoperative diagnosis and staging of breast cancer with a potential role especially when conservative surgery is planned after primary chemotherapy in LABC.