Purpose: Multicentric breast cancer has been considered to be a contraindication for sentinel node (SN) biopsy (SNB). In this prospective multi-institutional trial, SNB-feasibility and accuracy was evaluated in 142 patients with multicentric cancer from the Austrian Sentinel Node Study Group (ASNSG) and compared with data from 3,216 patients with unicentric cancer.
Patients and methods: Between 1996 and 2004, 3,730 patients underwent SNB at 15 ASNSG-affiliated hospitals. Patient data were entered in a multicenter database. One hundred forty-two patients presented with multicentric invasive breast cancer and underwent SNB.
Results: Intraoperatively, a mean number of 1.67 SNs were excised (identification-rate, 91.5%). The incidence of SN metastases was 60.8% (79 of 130). This was confirmed by axillary lymph node dissection (ALND) in 125 patients. Of patients with positive SNs, 60.8% (48 of 79) showed involvement of nonsentinel nodes (NSNs), as did three patients with negative SNs (false-negative rate, 4.0). Sensitivity, negative predictive value, and overall accuracy were 96.0%, 93.3%, and 97.3%, respectively. Ninety-one percent of the patients underwent mastectomy, and 9% were treated with breast conserving surgery. None of the patients have shown axillary recurrence so far (mean follow-up, 28.8 months). Compared with 3,216 patients with unicentric cancer, there was a significantly higher rate of SN metastases as well as in NSNs, whereas there was no difference in detection and false-negative rates.
Conclusion: Multicentric breast cancer is a new indication for SNB without routine ALND in controlled trials. Given adequate quality control and an interdisciplinary teamwork of surgical, nuclear medicine, and pathology units, SNB is both feasible and accurate in this disease entity.