Clinical Summary: 

• Design/Population: In the phase 3 SENOMAC trial, patients with clinically node-negative T1-3 breast cancer and 1 to 2 sentinel lymph node macrometastases were randomly assigned to either complete or omit axillary lymph node dissection. 
• Key Outcomes: Omission of axillary lymph node dissection was noninferior to completion of axillary lymph node dissection for overall survival and breast cancer-specific survival and was associated with significantly less long-term arm morbidity.
• Clinical Relevance: These findings support omission of  axillary lymph node dissection in appropriately selected patients with limited sentinel node involvement, reducing treatment-related morbidity without compromising oncologic outcomes.

Results from the phase 3 SENOMAC trial demonstrated that omission of axillary lymph node dissection following a positive sentinel lymph node biopsy did not compromise survival outcomes and significantly reduced long-term morbidity among patients with early-stage breast cancer.

These results were presented by Jana de Boniface, MD, PhD, Capio St. Göran's Hospital, Stockholm, Sweden, at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois.

In this noninferiority trial, 2766 patients with node-negative T1-3 invasive breast cancer with up to 2 sentinel lymph node macrometastases were randomized 1:1 to either complete (n = 1205) or omit (n = 1335) axillary lymph node dissection followed by adjuvant treatment. The primary end point was overall survival (OS). A key secondary end point was breast cancer-specific survival. Patient-reported outcomes were reported at 1 year, 3 years, and 5 years following randomization using Lymph-ICF (arm physical function), EORTC QLQ-C30, and BR23 (health-related quality of life). 

At a median follow-up of 60.1 months, 196 patients died, 75 of which were due to breast cancer. The 5-year OS rate was 93.4% in patients who completed axillary lymph node dissection and 94.4% in patients who omitted axillary lymph node dissection (P = .238). The 5-year breast cancer-specific survival rates were 97.3% and 97.8%, respectively (P = .504). 

The mean score difference in arm physical function assessed via Lymph-ICF was 6.14 at 3 years (P < .001) and 5.71 at 5 years (P < .001). Arm symptoms measured with the EORTC QLQ-BR23 questionnaire were significantly less severe among patients who did not undergo axillary lymph node dissection at both time points (P < .001). Global health-related quality of life did not differ significantly between treatment groups.

As Dr Boniface concluded, “omission of completion [axillary lymph node dissection] after a positive [sentinel lymph node] biopsy is oncologically safe and mitigates postoperative patient-reported arm morbidity.” 

Source: 

Boniface J, Tvedskov TF, Ryden L, et al. Omission of completion axillary dissection in patients with breast cancer and sentinel lymph node macrometastases: Overall survival and patient-reported arm morbidity from the randomized SENOMAC trial. Presented at the ASCO Annual Meeting. May 29 - June 2, 2026. Chicago, Illinois. LBA503.