SUMMARY: In 2025, the American Society of Clinical Oncology updated its guidelines on sentinel lymph node biopsy (SLNB) in patients with Stage I–II breast cancer undergoing upfront breast-conserving surgery. The recommendations reflect growing evidence that SLNB may be safely omitted in selected low-risk patients without compromising oncologic outcomes.
Historically, axillary surgery was performed for locoregional control, staging, and to guide adjuvant therapy. The move toward de-escalation is largely driven by the morbidity associated with axillary surgery. Although less invasive than Axillary Lymph Node Dissection (ALND), SLNB can still result in pain, restricted arm mobility, sensory changes, and lymphedema. Clinical trials have shown higher rates of postoperative complications and persistent upper extremity symptoms in patients undergoing SLNB compared with those who avoided axillary surgery.
Breast cancer–related lymphedema remains a significant long-term complication that can impair physical function, quality of life, and psychosocial well-being. Avoiding axillary surgery altogether is the most effective strategy for reducing this risk. As a result, the decision to omit SLNB should be individualized, balancing the value of nodal staging against surgical morbidity, patient preferences, and the likelihood that nodal findings would meaningfully alter adjuvant treatment decisions.
The updated ASCO guideline identifies clinical scenarios in which SLNB can be safely omitted because nodal involvement is unlikely to affect overall management.
1.Omission of Sentinel Lymph Node Biopsy (SLNB)
1.1 Criteria for Omitting SLNB
SLNB may be safely omitted in carefully selected patients with small (≤2 cm), clinically node-negative breast cancer when the results would not alter postoperative treatment decisions. Eligible patients should meet all of the following criteria:
- Postmenopausal and aged ≥50 years
- Unifocal invasive ductal carcinoma measuring ≤2 cm
- Nottingham grade 1 or 2 disease
- Hormone receptor–positive, HER2-negative tumors in patients planned for adjuvant endocrine therapy
- No suspicious lymph nodes identified on axillary ultrasound, or only one suspicious node with benign and concordant biopsy findings
- Undergoing breast-conserving surgery followed by whole-breast irradiation in patients younger than 65 years
Additional consideration:
For patients older than 70 years, current Choosing Wisely recommendations do not require axillary ultrasound when considering omission of SLNB.
1.2 Patients Aged ≥65 Years
Axillary surgery is not routinely required in patients aged ≥65 years who satisfy the criteria for SLNB omission. Evidence from prospective studies indicates that the likelihood of nodal involvement is very low in the following group:
- Postmenopausal women
- Tumors ≤2 cm
- Nottingham grade 1–2 disease
- Hormone receptor–positive, HER2-negative tumors
- Candidates for endocrine therapy
- Normal axillary ultrasound findings or a single suspicious node with benign concordant biopsy results
2. Impact of SLNB Omission on Adjuvant Therapy
2.1 Radiation Therapy
In patients meeting the criteria for SLNB omission, decisions regarding radiation therapy should remain unchanged. Omission of SLNB alone should not influence radiation treatment recommendations.
2.2 Systemic Therapy
Similarly, genomic assay testing and subsequent systemic treatment recommendations should not be modified solely because SLNB was omitted in appropriately selected patients.
Clinical note:
When chemotherapy decisions are being considered, genomic assays such as the 21-gene recurrence score may still be utilized to guide adjuvant treatment planning in the setting of omitted SLNB.
3. Axillary Lymph Node Dissection (ALND)
3.1 Breast-Conserving Surgery Patients
Completion ALND is generally not recommended for patients with early-stage, clinically node-negative breast cancer who undergo breast-conserving surgery and are found to have one or two positive sentinel lymph nodes, provided they will receive whole-breast radiation therapy.
Additional considerations:
- Completion ALND after positive SLNB may not be necessary when patients already meet criteria for treatment with CDK4/6 inhibitor or olaparib based on tumor biology.
- In a patient with 1-2 positive nodes on SLNB, and not otherwise eligible for CDK4/6 inhibitors or olaparib based on tumor biology, completion ALND can be considered.
- The rate of 4 or more nodal metastases with completion ALND after 1-2 positive SLNB is low (13%) and given the significantly higher morbidity of completion ALND compared with SLNB, treatment decisions should incorporate shared decision-making between physician and patient. to reduce treatment-related morbidity.
4.1 ALND in Patients Undergoing Mastectomy with Limited Nodal Disease
ALND may be omitted in patients with clinically node-negative invasive breast cancer measuring ≤5 cm who undergo mastectomy and are found to have one or two positive sentinel lymph nodes, provided that postmastectomy radiation therapy (PMRT) with Regional Nodal Irradiation (RNI) is planned.
4.2 ALND in Patients Not Receiving PMRT or RNI
For patients with pT1–T2, pN1 breast cancer undergoing mastectomy without planned PMRT or regional nodal irradiation, completion ALND is recommended.
4.3 ALND Prior to PMRT in Patients with Extensive Nodal Involvement
Patients undergoing mastectomy who are found to have four or more positive lymph nodes should undergo completion ALND followed by postmastectomy radiation (PMRT)
Sentinel Lymph Node Biopsy in Early-Stage Breast Cancer: ASCO Guideline Clinical Insights. Park KU, Vega RBM, Shams S, et al. JCO Oncol Pract. 2026; 22:748-754
