SENOMAC Trial Confirms Omitting Axillary Lymph Node Dissection Is Safe for Breast Cancer Patients with Sentinel Node Macrometastases
核心洞察
The phase III SENOMAC trial demonstrated that omitting completion axillary lymph node dissection (ALND) does not compromise overall survival in patients with 1–2 sentinel lymph node macrometastases, including those undergoing mastectomy and those with T2–T3 tumors.
At a median follow-up of 60.1 months, 5-year overall survival was 94.4% in the omission group versus 93.4% in the ALND group (HR 0.89; 95% CI, 0.67–1.17; P = .001 for non-inferiority).
Patients who skipped ALND reported significantly better arm function and fewer arm-related side effects at 1, 3, and 5 years, with persistent quality-of-life benefits.
Results from the international phase III SENOMAC trial have confirmed that omitting completion axillary lymph node dissection (ALND) is oncologically safe for patients with breast cancer (搜索) that has spread to one or two sentinel lymph nodes, while substantially reducing lasting arm-related morbidity. The findings, presented at the 2026 ASCO Annual Meeting in Chicago, expand the evidence base to include patient populations previously excluded from similar trials—namely those undergoing mastectomy and those with larger tumors.
The trial enrolled 2,540 patients (median age 61) from Sweden, Denmark, Germany, Greece, and Italy with primary invasive, clinically node-negative T1–T3 breast cancer (搜索) and up to two sentinel lymph node macrometastases (> 2 mm). Notably, 36.3% of participants underwent mastectomy and nearly 6% had tumors larger than 5 cm—groups for whom the safety of ALND omission had remained uncertain.
Survival Outcomes Confirm Non-Inferiority
After a median follow-up of 60.1 months, the 5-year overall survival rate was 94.4% in the omission group compared with 93.4% in the ALND group (HR 0.89; 95% CI, 0.67–1.17; P = .001 for non-inferiority). The upper boundary of the confidence interval fell comfortably below the prespecified non-inferiority margin of 1.44.
Breast cancer (搜索)-specific survival at 5 years was 97.9% in the omission group versus 97.2% in the ALND group (HR 0.75; 95% CI, 0.45–1.27). Overall, 203 participants died during follow-up, 74 of them from breast cancer.
"The key finding is that more axillary surgery in itself does not improve survival in these patients," said lead study author Jana de Boniface, MD, PhD, of Capio St. Göran's Hospital (搜索) and the Karolinska Institutet. "This is extremely important because it means that axillary surgery should be seen as a diagnostic instrument, not a therapeutic tool."
Durable Improvements in Arm Function and Quality of Life
Patient-reported outcomes consistently favored the omission group across all time points. Based on the Lymph-ICF questionnaire—which measures the impact of arm lymphedema (搜索) on daily activities—participants who skipped ALND reported significantly better arm function, with average score differences of 10.64 at 1 year, 10.73 at 3 years, and 10.75 at 5 years (scale 0–100, lower scores indicating fewer problems).
Similarly, the EORTC QLQ-BR23 questionnaire showed fewer arm symptoms in the omission group, with average score differences of 10.90 at 1 year, 9.86 at 3 years, and 10.02 at 5 years. Questionnaire response rates were 83% at 1 and 3 years and 81% at 5 years.
These findings carry substantial clinical weight given the known burden of ALND-related complications. According to the study authors, nearly 1 in 5 (19%) patients who undergo ALND report moderate problems with arm function 5 years later, and 13% report severe or very severe problems—including pain, numbness, limited arm mobility, and lymphedema (搜索).
Clinical Context and Implications
Earlier trials, notably ACOSOG Z0011, had suggested ALND could be safely omitted in select patients but were limited by their focus on breast-conserving surgery and tumors smaller than 5 cm. SENOMAC directly addressed these gaps.
"Completion ALND has long been standard practice following a positive sentinel lymph node biopsy, however ALND carries significant risks of arm-related morbidity," noted Jame Abraham, MD, FACP, Enterprise Chair of the Department of Hematology and Medical Oncology at Cleveland Clinic, in his review of impactful ASCO 2026 presentations. "I believe the findings do support omitting completion ALND in patients with two positive sentinel nodes, even those undergoing mastectomy—assuming they will receive adjuvant radiotherapy."
Dr. de Boniface emphasized that the recommendation should be viewed in context of the trial design: most patients received adjuvant locoregional radiotherapy according to current standards of care. The majority of participants (93.6%) had estrogen receptor-positive disease.
ASCO Perspective
"Lymphedema (搜索) can be a devastating quality-of-life issue that alters a woman's mobility, appearance, and self-esteem long after breast cancer (搜索) treatment is complete," said Jane Lowe Meisel, MD, FASCO, medical oncologist at Winship Cancer Institute of Emory University and an ASCO Expert in breast cancer. "This rigorous, large-scale trial proves that we can safely skip invasive axillary node dissection in patients with limited nodal disease, and that by avoiding this additional surgery, we can drastically reduce long-term arm complications and improve arm function for breast cancer patients even years out from their diagnosis."
Next Steps in Axillary Management
The SENOMAC investigators are now launching SENOMAC-ULTRA, a randomized trial comparing ALND against targeted axillary dissection—which removes significantly fewer lymph nodes—in patients with known axillary nodal spread. They are also conducting the T-REX trial to evaluate omission of nodal radiation therapy in patients with estrogen receptor-positive breast cancer (搜索) and 1–2 sentinel lymph node metastases who do not undergo ALND.
The SENOMAC trial was funded by the Swedish Cancer Society, the Swedish Scientific Council, the Nordic Cancer Union, and the Swedish Breast Cancer (搜索) Association.