Sentinel Lymph Node Biopsy (Breast)
What the Examiner Expects
Identification and removal of the first lymph node(s) draining the breast tumor to stage the axilla without a full axillary dissection. The ACOSOG Z0011 trial revolutionized axillary management: patients with T1-T2 tumors, 1–2 positive sentinel nodes, undergoing breast-conserving surgery with whole-breast radiation can safely omit ALND with no difference in overall survival or regional recurrence. The examiner expects you to know the injection technique (periareolar or peritumoral), the dual-tracer concept, and the Z0011 eligibility criteria.
Key Examiner Focus Points
- Dual tracer technique: technetium-99m sulfur colloid + isosulfan blue (or ICG)
- Identifies the first draining lymph node(s) from the tumor
- If SLN is negative: no further axillary surgery needed
- If SLN has macrometastasis (> 2 mm): ACOSOG Z0011 allows omission of ALND in selected patients
- Z0011 criteria: T1-T2, 1–2 positive SLNs, planned BCS + whole breast radiation, no extranodal extension
Common Curveballs
SLN shows isolated tumor cells (< 0.2 mm) on immunohistochemistry
Isolated tumor cells are classified as pN0(i+) — this is NOT a positive node. No further axillary surgery is needed. This does not affect adjuvant therapy decisions.
Patient had neoadjuvant chemotherapy and was clinically node-positive before treatment — SLN shows pathologic complete response
Targeted axillary dissection (TAD) with clipped node retrieval plus SLNB is the current approach for node-positive patients after neoadjuvant chemo. If ≥ 3 SLNs are removed including the clipped node and all are negative, ALND can be omitted. If residual disease is present, ALND is recommended.
Practice this topic with an AI-powered mock oral exam.
Browse Practice Cases