Sentinel Lymph Node Biopsy in Breast Cancer

Indications and Contraindications

The American Society of Clinical Oncology recommends sentinel lymph node biopsy (SLNB) as the standard of care for clinically node-negative early-stage breast cancer (T1-T2, stages I-II) undergoing upfront surgery, replacing routine axillary lymph node dissection for axillary staging 1, 2
The American Society of Clinical Oncology suggests that small invasive tumors (T1-T2, ≤5 cm) with clinically negative axillary nodes are the primary indication for SLNB 1, 3
Clinically node-negative patients confirmed by physical examination and negative preoperative axillary ultrasound are indicated for SLNB 1, 2
Patients undergoing either breast-conserving surgery or mastectomy are appropriate candidates for SLNB 4, 5

The American Society of Clinical Oncology guideline expanded indications to include multicentric tumors (clinically node-negative) - SLNB can be performed using subareolar or intradermal injection techniques that identify sentinel nodes for the entire breast 1, 6, 7
cT3-T4c tumors (clinically node-negative) - SLNB may be offered despite larger tumor size 1, 2
DCIS treated with mastectomy - SLNB should be considered to avoid a second operation if invasive cancer is found on final pathology (10-20% upstaging rate) 1, 6, 7
Large or high-grade DCIS undergoing mastectomy or immediate reconstruction, as axillary staging becomes impossible after reconstruction 6, 7
Obese patients - SLNB remains feasible despite slightly lower success rates with increasing body mass index 1, 7
Male breast cancer - SLNB is appropriate for staging 1, 8
Pregnant patients - SLNB may be offered (using radiotracer without blue dye to avoid fetal exposure) 1, 8
Prior breast or axillary surgery - SLNB can be performed with acceptable accuracy using alternative injection techniques 1, 8

Inflammatory breast cancer - false-negative rates are unacceptably high due to obstructed subdermal lymphatics containing tumor emboli 6, 7, 8
Clinically suspicious or palpable axillary lymph nodes - these patients require direct sampling or ALND rather than SLNB 3, 4, 9
N2/N3 stage disease (fixed or matted nodes, infraclavicular or supraclavicular involvement) 9

SLNB should only be performed by surgeons with demonstrated low false-negative rates (<10%) and high successful mapping rates (>90%) 3, 4, 9
Dual technique using both radiotracer and blue dye achieves the highest success rates and lowest false-negative rates compared to single-agent techniques 4
Complete clinical examination of the axilla must be performed intraoperatively to avoid missing palpable metastases that may cause false-negative SLNB 11, 9

For clinically node-negative early-stage breast cancer, low-risk patients (postmenopausal, ≥50 years, grade 1-2, HR+/HER2-, ≤2 cm, negative axillary ultrasound, breast-conserving therapy) → Consider omitting SLNB entirely 1, 9
Standard early-stage patients (T1-T2, clinically node-negative) → Perform SLNB 1, 2
Special circumstances (multicentric, cT3-T4c, DCIS with mastectomy, obese, male, pregnant, prior surgery) → May offer SLNB 1, 8
Contraindicated patients (inflammatory breast cancer, clinically positive nodes, N2/N3 disease) → Proceed directly to ALND 8, 9
After neoadjuvant therapy → SLNB may be performed if nodes become clinically negative 8, 5