The accuracy of sentinel lymph node biopsy in multicentric and multifocal invasive breast cancers

Sentinel lymph node biopsy (SLNB) has proved to be an accurate alternative to complete axillary lymph node dissection (ALND) in clinically node-negative breast cancer patients. Multicentric (MC) and multifocal (MF) invasive breast cancers are considered to be relative contraindications to SLNB. We examine the accuracy of SLNB in patients with MC and MF invasive breast cancers. From September 1996 to August 2001, a total of 3,501 patients with clinically node-negative breast cancer underwent SLNB using both blue dye and radioisotope at our institution. A total of 70 patients had MC or MF invasive breast cancer, a successful SLNB, and mastectomy for local control. All had ≥10 axillary nodes excised (including the SLN) in a planned ALND. Exclusion criteria included MC and MF in situ carcinoma; breast conservation; previous breast irradiation, ALND, or SLNB; recurrent breast cancer; neoadjuvant chemotherapy; or ALND based solely on SLNB pathologic examination. The incidence of axillary metastases was 54% (38 of 70). SLNB accuracy was 96% (67 of 70), sensitivity 92% (35 of 38), and false-negative rate 8% (3 of 38). All patients with an inaccurate SLNB had a dominant invasive tumor >5 cm and one patient had palpable axillary disease intraoperatively. The SLN was the only site of axillary metastasis in 37% (14 of 38). Results were compared with those of published SLNB validation studies, most of which reflect experience with single-site invasive breast cancers. No statistically significant difference was noted for accuracy, sensitivity, or false-negative rate. SLNB accuracy in MC and MF disease is comparable with that of published validation studies. MC and MF patients with a dominant T3 tumor (>5 cm) or axillary disease palpable intraoperatively should have a concurrent formal ALND. Our retrospective data suggest SLNB may be used as a reliable alternative to conventional ALND in selected patients with MC or MF disease. Further studies in this patient population are warranted.