Breast-Conserving Surgery vs. Mastectomy and SLND Indications in Early Breast Cancer
Primary Surgical Approach
Breast-conserving surgery (BCS) with post-operative radiotherapy is the preferred local treatment option for the majority of patients with early breast cancer 1. This approach provides equivalent survival outcomes to mastectomy while offering superior quality of life, fewer complications, and better cosmetic results 1, 2.
Indications for Breast-Conserving Surgery
BCS is appropriate for patients meeting the following criteria:
- Tumor characteristics: Stage I and II disease with tumors ≤3-3.5 cm 1, 3
- Unifocal or unicentric disease without multicentricity 1, 4
- Ability to achieve clear surgical margins (generally >2 mm, though margins >10 mm are considered adequate and <1 mm inadequate) 1
- Favorable tumor-to-breast size ratio allowing adequate resection with acceptable cosmesis 1
- Patient willingness to undergo post-operative whole-breast radiotherapy 1
Contraindications to BCS (Mastectomy Indicated)
Mastectomy should be performed when:
- Multicentric tumors are present 1, 4
- Large tumors (>3-4 cm) in small breasts where adequate margins cannot be achieved without unacceptable cosmetic outcome 1
- Positive margins after resection that cannot be re-excised 1
- Inflammatory breast cancer 1
- Prior radiation to the chest wall or breast 1
- Patient preference for mastectomy 1
When mastectomy is indicated or preferred, breast reconstruction should be offered, except for primary inflammatory and other high-risk tumors where delays in systemic/radiation treatment would compromise care 1.
Sentinel Lymph Node Dissection (SLND) Indications
Standard Indications for SLND
SLNB is the standard axillary surgery in all clinically node-negative (cN0) patients with early-stage breast cancer 1. This represents the current standard of care, replacing routine axillary lymph node dissection (ALND) for staging purposes 1, 5.
When SLND Can Be OMITTED
SLND should not be routinely recommended in highly select patients who are postmenopausal, ≥50 years of age, with negative preoperative axillary ultrasound, grade 1-2, small (≤2 cm), hormone receptor-positive, HER2-negative breast cancer who undergo breast-conserving therapy 1, 6. This represents the most recent evidence-based approach to de-escalating axillary surgery in very low-risk patients 1.
SLND in Special Circumstances
SLND may be offered in the following situations:
- Multicentric tumors (clinically node-negative) 1
- DCIS treated with mastectomy (because this precludes subsequent SLNB at a second operation) 1
- Prior breast and/or axillary surgery 1
- Preoperative/neoadjuvant systemic therapy (though accuracy may be reduced; targeted axillary dissection with clipped node removal plus ≥3 SLNs reduces false-negative rates to <5%) 1
- Patients who are obese, male, or pregnant 1, 6
- cT3-T4c tumors (clinically node-negative) 1, 6
When SLND Should NOT Be Performed
Clinicians should not perform SLNB in the following circumstances:
- DCIS when breast-conserving surgery is planned (insufficient evidence to support routine use) 1
- Inflammatory breast cancer 1
- Large or locally advanced invasive breast cancers (T3/T4) with clinically positive nodes 1
- Pregnancy (though recent guidelines suggest it may be offered) 1
- Palpable axillary nodes or clinically positive axilla 1, 6
- Initial bulky nodal involvement (cN2-3) even if converted to ycN0 after neoadjuvant therapy 1
Management Based on SLND Results
Negative Sentinel Nodes
Clinicians should not recommend ALND for patients with early-stage breast cancer who do not have nodal metastases 1, 6. This is a strong recommendation based on high-quality evidence showing no survival difference with 15-year follow-up 6.
1-2 Positive Sentinel Nodes
After Breast-Conserving Surgery
Clinicians should not recommend ALND for patients with early-stage breast cancer who have 1-2 sentinel lymph node metastases and will receive breast-conserving surgery with whole-breast radiotherapy 1, 6. This strong recommendation is based on the ACOSOG Z0011 trial showing equivalent survival without completion ALND 6.
In the absence of prior neoadjuvant therapy, patients with micrometastatic spread and those with limited SLN involvement (1-2 affected SLNs) in cN0, following BCS with subsequent whole-breast radiotherapy, eventually including the lower part of axilla and adjuvant systemic treatment, do not need further axillary surgery 1.
After Mastectomy
Clinicians may offer post-mastectomy radiation with regional nodal irradiation and omit ALND in patients with clinically node-negative invasive breast cancer ≤5 cm who receive mastectomy and have 1-2 positive sentinel nodes 1, 6. This approach results in significantly lower lymphedema rates compared to ALND 6.
Alternatively, clinicians may offer ALND for women with early-stage breast cancer with nodal metastases found on SNB who will receive mastectomy, though this is a weak recommendation based on low-quality evidence 1.
≥3 Positive Sentinel Nodes
ALND followed by regional nodal irradiation should be recommended in patients who receive mastectomy and have ≥3 positive sentinel nodes 6. ALND following positive SLNB with <3 involved SLNs is generally recommended only in case of expected high axillary disease burden or impact on further adjuvant systemic treatment decisions 1.
Critical Pitfalls to Avoid
- Do not default to ALND for micrometastases in patients meeting criteria for SLND alone 6
- Do not perform ALND based solely on imaging findings of suspicious nodes without pathologic confirmation 6
- Ensure SLNB is only performed by surgeons with demonstrated low false-negative rates and high successful mapping rates 6
- Mark the primary tumor site and positive lymph nodes before neoadjuvant therapy to facilitate accurate surgery and targeted axillary dissection 1
- Use dual tracer technique and remove ≥3 SLNs (including the clipped node) after neoadjuvant therapy to reduce false-negative rates to <5% 1
- Do not routinely offer SLNB after neoadjuvant therapy in patients with initial cN2-3 disease even if converted to ycN0 1