Dr de Boniface on Encouraging SENOMAC Trial Data

In an interview onsite at the 2026 ASCO Meeting in Chicago, IL, Jana de Boniface, MD, Karolinska Institutet, discusses results from the phase 3 SENOMAC trial. The findings confirm that omitting a completion axillary lymph node dissection (ALND) is safe for breast cancer patients with one or two sentinel lymph node macrometastases. For decades, a positive sentinel node biopsy typically led to an ALND to remove additional lymph nodes. While this provided better staging information, it frequently caused severe, long-term arm morbidity.

At a median follow-up of 60.1 months, the trial established the clinical non-inferiority of omitting the procedure. The 5-year overall survival rate was 94.4% in the omission group compared to 93.4% in the completion ALND group. Breast cancer-specific survival rates were also nearly identical (97.9% versus 97.2%). Notably, these survival rates held true despite additional cancer being found in 34.3% of the ALND patients—meaning residual disease left untreated in the omission group had no negative impact on survival.

The trial successfully filled critical data gaps by enrolling 2540 patients across five European nations, deliberately including historically excluded subgroups: 36% underwent mastectomies and 6% had tumors larger than 5 cm.

Patient-reported outcomes over 5 years revealed that avoiding ALND dramatically reduces complications and preserves quality of life:

• Arm Function: The omission group reported consistently better lymphedema-related arm function and stable, lower symptom scores at 1, 3, and 5 years.
• Physical Impairment: At 5 years, 12.6% of the ALND group reported severe arm physical function problems, compared to just 3.6% in the omission group.
• Quality of Life: Global health scores consistently favored the omission group across all time points.

Ultimately, the trial proves that axillary surgery should be viewed as a diagnostic instrument rather than a therapeutic tool. Building on these findings, investigators are launching the SENOMAC-ULTRA trial to evaluate further surgical de-escalation.