- When to perform sentinel lymph node mapping and biopsy?
- cT1N0, 65 y, HR+/HER2–, tumor 1.5 cm, negative axillary US, breast-conserving surgery (BCS). SLNB or omit?
- Omission of SLNB is reasonable per ASCO 2025 criteria:
- Low-risk, ≥ 50 years, HR+ / HER2-, ≤ 2 cm, negative pre-op axillary imaging, BCS:
- After shared decision-making
- Low-risk, ≥ 50 years, HR+ / HER2-, ≤ 2 cm, negative pre-op axillary imaging, BCS:
- Omission of SLNB is reasonable per ASCO 2025 criteria:
- Same patient as #1 but undergoing mastectomy. SLNB?
- Perform SLNB:
- Even if cN0, mastectomy removes future SLNB opportunity:
- Most guidelines advises SLNB at mastectomy in case invasive disease or nodal information will alter RT /systemic therapy
- Define the standard indications for SLNB in invasive cT1 to T2, cN0 disease:
- SLNB is standard for staging in clinically node-negative invasive cancers:
- Exceptions include specific low-risk cohorts where omission is now endorsed
- Omission is reasonable per ASCO 2025 criteria:
- Low-risk, ≥ 50 y, HR+/HER2–, ≤ 2 cm, negative pre-op axillary imaging, BCS, after shared decision-making
- SLNB is standard for staging in clinically node-negative invasive cancers:
- Pure DCIS having lumpectomy – do you stage the axilla?
- No:
- Pure DCIS treated with BCS does not need SLNB
- No:
- DCIS requiring mastectomy – do you add SLNB?
- Yes:
- Perform SLNB at mastectomy because later mapping is unreliable and occult invasion risk exists
- Yes:
- Role of pre-op axillary ultrasound (US) before SLNB?
- US triages patients:
- If suspicious nodes, biopsy to confirm cN+:
- If negative and tumor low-risk, supports SLNB omission in ASCO-defined cohorts
- If suspicious nodes, biopsy to confirm cN+:
- US triages patients:
- SOUND trial bottom line for small tumors with negative axillary US:
- In cT1 ≤ 2 cm, cN0 with negative US, no axillary surgery was non-inferior to SLNB for 5-year distant DFS
- INSEMA trial bottom line (NEJM 2025):
- Among cT1 to cT2, cN0 undergoing BCS, omitting axillary surgery was non-inferior to SLNB for invasive DFS, with less morbidity
- Does NCCN acknowledge de-escalation of axillary surgery in select early-stage cases?
- Yes – NCCN endorses risk-adapted axillary management; details in current NCCN Breast Cancer Guideline
- Key counseling points when considering SLNB omission
- Ensure negative axillary imaging, small HR+ / HER2-tumor, BCS with adjuvant therapy, and that nodal information won’t change systemic / RT plans; use shared decision-making
- cT1N0, 65 y, HR+/HER2–, tumor 1.5 cm, negative axillary US, breast-conserving surgery (BCS). SLNB or omit?
- Omission of SLNB in Early Breast Cancer – ASCO 2025 / SOUND / INSEMA Trials;
- ASCO 2025 Guideline Update (“Sentinel Lymph Node Biopsy in Early-Stage Breast Cancer”) provides formal recommendations to omit routine SLNB in select patients:
- The criteria include:
- Age ≥ 50 and postmenopausal status
- HR positive
- HER2 negative
- Tumor grade 1 to 2
- ≤ 2 cm size
- Clinically node negative (by exam)
- Negative on preoperative axillary ultrasound (or a suspicious node that is benign on biopsy)
- Undergoing breast-conserving therapy with whole-breast irradiation (WBRT) ideally (for patients < 65; for older patients there is more flexibility)
- The criteria include:
- Trials supporting this omission:
- SOUND trial – randomized patients with T1 (≤ 2 cm), cN0 breast cancer and negative axillary ultrasound to SLNB vs no axillary surgery:
- At 5 years, distant disease-free survival was similar in both arms
- INSEMA trial – included clinically node-negative invasive breast cancer ≤ 5 cm undergoing BCS:
- This trial found omission of axillary surgery was non-inferior to SLNB in terms of invasive disease-free survival
- SOUND trial – randomized patients with T1 (≤ 2 cm), cN0 breast cancer and negative axillary ultrasound to SLNB vs no axillary surgery:
- Morbidity / Quality of life data:
- In the INSEMA trial, omitting SLNB led to lower rates of persistent lymphedema:
- ~ 1.8% in omission vs 5.7% in SLNB group
- Other arm morbidity measures like restricted shoulder / arm movement and pain were significantly less in the omission group
- These differences are clinically significant, especially considering the trade-off between morbidity and marginal gain in prognostic information in low-risk patients
- In the INSEMA trial, omitting SLNB led to lower rates of persistent lymphedema:
- Risks / caveats:
- Even in SOUND and INSEMA trials, almost all patients still got radiotherapy (WBRT) which likely contributed to controlling any microscopic nodal disease
- The longer follow-up is needed to ensure late recurrences in HR+ disease are not missed:
- ASCO guidelines recognize that.
- ASCO 2025 Guideline Update (“Sentinel Lymph Node Biopsy in Early-Stage Breast Cancer”) provides formal recommendations to omit routine SLNB in select patients:
- Positive sentinel nodes: who still needs ALND?
- Z0011 scenario:
- BCS + whole-breast RT, 1 to 2 positive SLNs (no gross ECE). ALND needed?
- No. Omit ALND – no OS / DFS detriment at 10 years
- BCS + whole-breast RT, 1 to 2 positive SLNs (no gross ECE). ALND needed?
- IBCSG 23-01:
- Micromets (≤ 2 mm) in SLN – ALND?
- No:
- Omit ALND; 10-year outcomes show safety
- No:
- Micromets (≤ 2 mm) in SLN – ALND?
- AMAROS take-home when SLN positive (mostly macromets):
- Axillary RT provides comparable regional control to ALND with less lymphedema – a de-escalation option
- Does Z0011 apply to mastectomy?
- No:
- Z0011 included lumpectomy + whole-breast RT only
- If mastectomy and SLN+, decisions differ:
- ALND or nodal radiation often considered
- No:
- > 2 positive SLNs at upfront surgery – what’s recommended?
- ALND or nodal RT (RNI) typically indicated
- Z0011 criteria not met
- ALND or nodal RT (RNI) typically indicated
- Gross extranodal extension (ENE) in SLN on pathology – management?
- Generally ALND (or comprehensive RNI) considered:
- Most de-escalation trials excluded gross ENE
- Generally ALND (or comprehensive RNI) considered:
- Under-coverage RT plans (no low-axilla tangents) but 1 to 2 SLN+ after BCS – omit ALND
- Be cautious:
- Z0011 assumed tangential fields. If axilla not covered, many favor ALND or add nodal RT
- Be cautious:
- Inflammatory breast cancer – axillary staging approach?
- ALND indicated:
- SLNB is unreliable
- ALND indicated:
- cT3 / cT4 tumors but cN0, BCS planned – Z0011 applicable?
- Z0011 enrolled T1 to T2:
- Extrapolation to T3 / T4 is not evidence-based – individualize, often favor completion treatment
- Z0011 enrolled T1 to T2:
- Do isolated tumor cells (ITCs) in SLN mandate ALND?
- No; ITCs (pN0[i+]) do not require ALND
- Z0011 scenario:
- ACOSOG Z0011 – ALND vs No ALND when SLNs positive
- Population and design:
- Women with clinical T1 or T2 invasive breast cancer, no palpable axillary adenopathy, 1 to 2 sentinel lymph nodes positive by hematoxylin and eosin stain
- All underwent lumpectomy + WBRT + adjuvant systemic therapy
- Median follow-up ~ 9.3 years
- Population and design:
- Hazard Ratios / Noninferiority:
- The study had a prespecified noninferiority margin of HR = 1.3 for OS:
- The observed HR was 0.85 (SLND alone vs ALND) for OS; P = .02 for noninferiority
- DFS had HR 0.85 (95% CI 0.62-1.17), i.e. no statistically significant difference
- The study had a prespecified noninferiority margin of HR = 1.3 for OS:
- Applicability limits (i.e. external validity constraints):
- Excluded patients with > 2 positive SLNs, gross extranodal extension, patients undergoing mastectomy without RT, or those not getting WBRT tangents as per protocol:
- So results apply only to those meeting Z0011 criteria
- Excluded patients with > 2 positive SLNs, gross extranodal extension, patients undergoing mastectomy without RT, or those not getting WBRT tangents as per protocol:
- Additional / Supporting Data and Real-World Observations:
- Risk of lymphedema:
- ALND is associated with significantly higher rates of lymphedema, shoulder mobility limitations, and arm pain than SLNB alone
- Studies show that lymphedema incidence after SLNB is much lower (e.g., single digits) compared to ALND (where rates may be 20% to 30+% depending on patient, RT, etc.)
- The SOUND / INSEMA omission studies show ~ 5% to 6% lymphedema in SLNB arm vs ~1% to 2% when SLNB omitted
- Ultrasound negative imaging correlate:
- In ASCO guideline and supporting articles, it’s noted that when axillary US is negative preoperatively in low-risk patients, ~85% of the time the SLNB is also negative
- So negative US is a strong predictor and helps avoid unnecessary SLNB in selected patients.
- Long-term axillary recurrence rates:
From Z0011:- Regional recurrence was < 1% over the 10 years in SLNB alone group
- Real-world data (e.g. from NSABP, other cohorts) confirm similar low regional recurrence in patients meeting Z0011 criteria with SLNB alone
- Risk of lymphedema:
- Putting It All Together: Key Data-Driven Pearls:
- For a patient meeting Z0011 criteria (T1 to T2, cN0, 1 to 2 SLNs positive, lumpectomy + WBRT + systemic therapy):
- Omitting ALND results in noninferior OS and DFS at 10 years, with very low regional recurrence (< 1%)
- In the ASCO 2025 SLNB omission group (SOUND, INSEMA), for low-risk patients (≤2 cm, HR+/HER2-, grade 1-2, ≥ 50 y, negative US):
- Omission of SLNB is noninferior in invasive disease–free or distant disease-free survival at 5 years
- Also, nodal positivity on SLNB in these patients is relatively uncommon
- The trade-off:
- Small absolute increase in risk of occult nodal disease vs measurable reduction of morbidity (lymphedema, pain, mobility)
- For many patients, quality of life gains are meaningful
- For a patient meeting Z0011 criteria (T1 to T2, cN0, 1 to 2 SLNs positive, lumpectomy + WBRT + systemic therapy):
Rodrigo Arrangoiz MS, MD, FACS, FSSO 