- Neoadjuvant chemotherapy (NAC) and the axilla:
- Biopsy-proven cN1 starting NAC – what to do before therapy?
- Clip / mark the positive node to enable targeted axillary dissection (TAD) after NAC
- After NAC, exam / US cN0 – can SLNB be used? Main concern?
- Yes:
- But false-negative rate (FNR) is the issue
- Use techniques to reduce FNR:
- Dual tracers
- ≥ 2 to 3 SLNs
- Retrieval of the clipped node
- Yes:
- Z1071 FNR headline and mitigation strategies:
- Overall FNR about:
- 12% to 13%
- ≥ 3 SLNs, dual tracers, and removal of the clipped node lower FNR
- Overall FNR about:
- SENTINA insights:
- Identification and FNR vary by timing:
- SLNB after NAC in initially node-positive patients has higher FNR unless optimized
- SN-FNAC findings:
- With rigorous pathology (IHC) and adequate technique, FNR can be ≈ 8% to 13%:
- Still requires careful selection
- With rigorous pathology (IHC) and adequate technique, FNR can be ≈ 8% to 13%:
- Identification and FNR vary by timing:
- What is TAD and why use it post-NAC?
- TAD = SLNB + removal of the clipped metastatic node:
- Improves accuracy and lowers FNR versus SLNB alone
- TAD = SLNB + removal of the clipped metastatic node:
- If post-NAC axilla remains cN+ clinically or by imaging / biopsy – management?
- ALND (and consideration of RNI) remains standard
- Subtype and nodal pCR expectations after NAC:
- HER2+ and TNBC have higher nodal pCR, supporting de-escalation strategies when cN1→cN0 with optimized technique
- Do you routinely perform SLNB before NAC in cN0 to “bank” nodes?
- Not routinely; most proceed with SLNB after NAC in cN0, reserving pre-NAC SLNB for select scenarios
- If the clipped node is not retrieved at surgery post-NAC but SLNs are negative – what now?
- Higher FNR concern; many advocate completion ALND or targeted re-localization to ensure the clipped node is removed
- Biopsy-proven cN1 starting NAC – what to do before therapy?
- Radiation interfaces (ASTRO-ASCO-SSO; PMRT/RNI):
- How do PMRT / RNI guidelines intersect with axillary surgery choices?
- Updated ASTRO-ASCO-SSO PMRT guidance:
- Chest wall / breast plus regional nodes (including axilla) are addressed based on pathologic and clinical risk
- In some SLN+ cases axillary RT may substitute for ALND
- Z0011 vs regional nodal irradiation (RNI) big picture:
- Z0011 patients had excellent outcomes with tangents; comprehensive nodal RT can also control axilla but with different toxicity trade-offs
- Updated ASTRO-ASCO-SSO PMRT guidance:
- After mastectomy with 1 to 3 positive nodes – axillary management?
- Often PMRT with RNI is recommended
- ALND may be performed depending on surgical/RT plan and extent of disease
- Can axillary RT replace ALND for SLN+ in BCS patients (AMAROS principle)?
- Yes – axillary RT offers comparable control with less lymphedema vs ALND
- Does omission of SLNB (SOUND / INSEMA) change systemic therapy decisions?
- In properly selected low-risk cohorts, nodal information rarely changes systemic therapy, enabling safe omission
- How do PMRT / RNI guidelines intersect with axillary surgery choices?
- Practical technique and pathology:
- Minimum SLN count to reduce FNR post-NAC?
- Try to retrieve ≥ 2 to 3 SLNs:
- More is better for accuracy
- Try to retrieve ≥ 2 to 3 SLNs:
- Mapping agents: single vs dual tracer?
- Dual tracer (radioisotope + blue dye / ICG) reduces FNR:
- Especially post-NAC
- Dual tracer (radioisotope + blue dye / ICG) reduces FNR:
- What to do with ITCs (pN0[i+]) post-NAC?
- Treat as node-negative for surgical decision-making
- Escalate RT / systemic therapy only if other factors indicate
- How do micrometastases (pN1mi) affect ALND decisions in upfront BCS
- Per IBCSG 23-01:
- ALND can be omitted with micrometastases
- Per IBCSG 23-01:
- Grossly matted / fixed nodes at presentation (cN2 to N3) – initial surgical plan?
- These patients generally need systemic therapy and ALND (with RNI), not SLNB
- Minimum SLN count to reduce FNR post-NAC?
- Special scenarios:
- Pregnancy and SLNB – allowed?
- Yes, with Tc-99m only (avoid blue dye anaphylaxis risk; methylene blue contraindicated in 1st trimester):
- Institutional policies vary. (ASBrS technique guidance)
- Yes, with Tc-99m only (avoid blue dye anaphylaxis risk; methylene blue contraindicated in 1st trimester):
- Prior breast / axillary surgery – impact on SLN mapping?
- Prior surgery / radiation can alter drainage:
- SLNB still feasible but may have lower identification rates:
- Consider imaging aid
- SLNB still feasible but may have lower identification rates:
- Prior surgery / radiation can alter drainage:
- Local recurrence after previous SLNB – repeat SLNB?
- Possible in selected cases; mapping may identify alternate basins; MDT discussion is key
- Male breast cancer – apply same axillary algorithms?
- Generally yes:
- SLNB for cN0 invasive disease, with similar de-escalation logic when applicable
- Generally yes:
- Medullary-like or tubular carcinoma – special SLNB rules?
- No unique rules:
- Follow general cN0 invasive management:
- SLNB unless low-risk omission criteria met
- Follow general cN0 invasive management:
- No unique rules:
- Pregnancy and SLNB – allowed?
- Gray zones and decision-making:
- If genomic assay selection might hinge on nodal status, should you still omit SLNB?
- If nodal status would alter systemic therapy decisions (e.g., chemotherapy indication):
- Perform SLNB
- Omission is for cases where nodal information won’t change therapy
- If nodal status would alter systemic therapy decisions (e.g., chemotherapy indication):
- How do you counsel about lymphedema risk when comparing SLNB vs ALND vs axillary RT:
- Lymphedema risk:
- ALND > axillary RT > SLNB > omission
- AMAROS shows less lymphedema with RT vs ALND
- Lymphedema risk:
- If SLN is positive and patient is not a candidate for whole-breast RT (e.g., declines RT) after BCS – omit ALND
- Z0011 required WBRT; without RT coverage, many favor ALND
- Clinically negative axilla but suspicious single node on imaging with benign core biopsy – proceed with SLNB or omit?
- Proceed with SLNB (or omission only if fully meeting SOUND / ASCO criteria and MDT agrees imaging is truly negative / safe)
- If genomic assay selection might hinge on nodal status, should you still omit SLNB?
- Bottom line:
- When is ALND still clearly indicated today?
- Inflammatory breast cancer
- Persistent cN+ after NAC
- >2 SLNs positive in upfront BCS /mastectomy
- Gross ENE
- When RT plans won’t cover low axilla
- Nodal information is needed
Rodrigo Arrangoiz MS, MD, FACS, FSSO 