Sentinel Node Biopsy Without Axillary Dissection in Patients with Sentinel-Node Metastases

A current trend in breast cancer therapy is to de-escalate treatment when appropriate. For local therapy, this trend has focused on decreasing the emphasis on axillary lymph node dissection (ALND). In the randomized, phase 3, European noninferiority SENOMAC trial, researchers evaluated whether omitting completion ALND after sentinel lymph node biopsy (SLNB) would not worsen overall survival (OS). Patients with T1–3 tumors and one or two sentinel node macrometastases (>2 mm) were eligible. In contrast to previous studies, the investigators allowed patients with additional micrometastases or with extracapsular nodal extension.

Of the 2540 patients, 40% were aged 65 or older, 94% had T1 or T2 tumors, 64% had breast-conserving surgery, 70% had one or two sentinel nodes removed, and 87% had luminal ER+/HER2− tumors. Approximately one third of patients had extracapsular nodal extension. Approximately 65% of patients received adjuvant chemotherapy, 88% received postoperative regional nodal radiation therapy, 93% received adjuvant endocrine therapy, and 9% received HER2-directed therapy. Median follow-up was 46.8 months.

The estimated 5-year OS, the primary endpoint, was similar in the ALND- and SLNB-only arms (92% and 93%), although statistical power could not yet be calculated. The two arms also had similar 5-year breast cancer–specific survival (97%) and 5-year recurrence-free survival (89% and 90%).