Breast Cancer Treatment
Surgical Options
Sentinel Lymph Node Biopsy (SLNB)
Indications:
- T1 and T2 sized tumors (≤ 5 cm)
- Multicentric disease
- DCIS when mastectomy is planned
- Older/obese patients
- Men with breast cancer
Technique:
- Inject vital blue dye and/or technetium-labeled sulfur colloid peri-tumor or peri-areolar
- Drain to sentinel LN → surgeon sees blue dye + uses gamma probe
- Localizes sentinel node in 90% of patients
- Overall accuracy: 98.2%, false negative rate: 5.8%
- Pregnant patients: sulfur colloid only (not blue dye — unknown fetal effects)
Board Pearl
Z0011 trial: In T1-T2 breast cancer with 1–2 positive SLNs, lumpectomy + adjuvant systemic therapy + tangential-field WBI, ALND did NOT significantly affect OS or DFS. Ineligible: T3 tumors, clinically positive LNs, ≥3 positive SLNs, gross extranodal extension, mastectomy, NAC, or partial-breast radiation.
Lumpectomy (Breast-Conserving Therapy)
- Surgical removal of known cancer (invasive or DCIS)
- Positive margins = invasive cancer or DCIS at inked surface of resection
- Focally positive margins = cancer at margin over length ≤ 4mm, or ≤ 3mm low power fields
- Close margins (DCIS) = DCIS ≤ 2mm from inked surface
- Without re-excision, chance of recurrence: 14% at 7 years if focally positive (vs. 7% if negative)
- Higher likelihood of positive margins: larger tumor (> 2 cm), high-grade, positive LNs, extensive intraductal component, partially/non-calcified DCIS, ILC, young age, multifocal disease
Radiation Therapy
Whole Breast Irradiation (WBI)
- Typically starts 2–5 weeks after lumpectomy
- 5 days/week for 6 weeks (40–50 Gy)
- Recurrence rate: 6–14% with XRT vs. 25–36% without XRT
Accelerated Partial Breast Irradiation (APRI)
- High dose localized to lumpectomy site
- 5-day period
- Methods: intracavitary brachytherapy (inflatable balloon), interstitial brachytherapy (multiple afterloading catheters), intraoperative radiation therapy
- Higher local recurrence rate than WBI, but no difference in overall survival
Systemic Therapy
Oncotype Dx
- Assay predicting likelihood of recurrence and response to chemotherapy
- Score 0–100
- Low RS (< 18): Good prognosis — will often respond to hormone therapy alone
- High RS (≥ 31): Likely needs chemotherapy
Neoadjuvant Chemotherapy (NAC)
Indications:
- Inflammatory carcinoma
- Known metastasis to axilla
- Known systemic disease
- Large primary lesion where conservative therapy is not possible unless tumor shrinks
Hormonal Therapy (ER+ Breast Cancer)
| Drug Class | Examples | Mechanism |
|---|---|---|
| SERM (Selective Estrogen Receptor Modulator) | Tamoxifen, Raloxifene, Clomifene | Competitive partial agonists of estrogen receptor |
| Aromatase Inhibitors (AIs) | Letrozole (Femara), Anastrozole (Arimidex), Exemestane (Aromasin) | Block aromatase → decrease estrogen production |
Targeted Therapy
- Trastuzumab (Herceptin): HER2/Neu+ breast cancer; monoclonal antibody targeting HER2; causes downregulation of HER2
Low-Value Treatments (Choosing Wisely)
The American College of Surgeons, Society for Surgical Oncology (SSO), and American Society of Breast Surgeons identified 4 low-value breast cancer treatments to eliminate:
- ALND for limited nodal disease in patients receiving lumpectomy and radiotherapy
- Lumpectomy re-excision for close but negative margins for invasive cancer
- Contralateral prophylactic mastectomy (CPM) in average-risk women with unilateral cancer
- SLNB in clinically node-negative women ≥ 70 years old with hormone receptor-positive (HR+) cancer
Margins
| Term | Definition | Management |
|---|---|---|
| Positive margins | Invasive cancer or DCIS at inked surface | Re-excision |
| Focally positive | Cancer at margin ≤ 4mm or ≤ 3mm lpp | Re-excision |
| Close (DCIS) | DCIS ≤ 2mm from inked surface | Discuss re-excision |
| After re-excision if still positive | Margins still positive | Usually → mastectomy |
Anticoagulation Management for Breast Biopsies
Per SIR Consensus Guidelines:
| Anticoagulant | Hold Time |
|---|---|
| NSAIDs (ibuprofen, etc.), fish oil, vitamin E | Do not withhold |
| Aspirin (prescribed) | Do not withhold |
| Aspirin (wellness) | 5 days |
| Clopidogrel (Plavix) | 5 days |
| Rivaroxaban (Xarelto), Apixaban (Eliquis) | 3 days |
| Dabigatran (Pradaxa), Fondaparinux (Arixtra) | 2–3 days |
| Enoxaparin (Lovenox) | 12 hrs (hold AM dose) |
| Warfarin (Coumadin) | 5 days, correct to INR < 2.0 |