Clinical Practice Guideline for Breast-Conserving Surgery in 2021

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Clinical Practice Guideline for Breast-Conserving Surgery in Patients with Early-Stage Breast Cancer: Chinese Society of Breast Surgery (CSBrS) Practice Guidelines 2021

Breast-conserving surgery (BCS) combined with radiotherapy has been established as the primary surgical approach for eligible patients with early-stage breast cancer. The Chinese Society of Breast Surgery (CSBrS) developed these guidelines to standardize clinical practice, building upon their 2019 consensus document. The 2021 guidelines incorporate updated evidence and expert discussions, focusing on indications, contraindications, surgical techniques, pathological assessments, and radiotherapy protocols.

Level of Evidence and Recommendation Strength

The guideline development involved 85 multidisciplinary experts, including breast surgeons, oncologists, radiologists, pathologists, and epidemiologists. Recommendations were graded using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system:

  • Level I: High-quality evidence from randomized controlled trials (RCTs) or meta-analyses.
  • Level II: Moderate-quality evidence from observational studies or RCTs with limitations.
  • Recommendation Strength A: Strong consensus for implementation.

Key Recommendations

Indications for BCS

  1. Patient preference for breast preservation (Level I, Strength A).
  2. Clinical Stage I, II, or ≤T2 tumors (tumor size ≤5 cm) (Level I, Strength A).
  3. Achievable acceptable cosmetic outcomes post-BCS (Level I, Strength A).

Contraindications for BCS

  1. Radiotherapy contraindications (e.g., active connective tissue disease) (Level I, Strength A).
  2. Positive surgical margins after resection (Level I, Strength A).
  3. Extensive microcalcifications on imaging (Level I, Strength A).
  4. Inflammatory breast cancer (Level I, Strength A).
  5. Patient refusal of BCS (Level I, Strength A).

Surgical Considerations

  • Oncoplastic techniques improve cosmetic outcomes (Level II, Strength A). These include tissue rearrangement or volume replacement to optimize breast shape.
  • Titanium clip placement in the surgical bed is recommended to guide radiotherapy boosts (Level I, Strength A).

Pathological Margin Assessment

  1. Mandatory margin evaluation (Level I, Strength A).
  2. Intraoperative frozen section analysis (FSA) reduces re-excision rates (Level I, Strength A).
  3. Post-operative formalin-fixed, paraffin-embedded analysis confirms margin status (Level I, Strength A).

Margin Assessment Techniques

  • Perpendicular inked method: The specimen is inked, and margins are examined perpendicularly (Level I, Strength A).
  • Tangential shaved method: Shaved margins parallel to the resection surface (Level II, Strength A).
  • Cavity wall sampling: Biopsies from the tumor bed after excision (Level II, Strength A).

The panel emphasized that “no ink on tumor” is sufficient for invasive ductal carcinoma, while ≥2 mm margins are advised for ductal carcinoma in situ (DCIS). However, Chinese real-world data (CSBrS-005, 2019) showed 88.2% of patients had margins >5 mm, reflecting a cautious approach in clinical practice.

Radiotherapy Protocols

  1. Whole-breast irradiation (WBI) is standard post-BCS (Level I, Strength A).

  2. Exceptions to WBI:

    • Patients aged >65 years with Stage I, hormone receptor-positive tumors, and negative margins (per CALGB9343 trial data).
    • Omission of WBI in this subgroup resulted in a 10-year local recurrence rate of 10% vs. 2% with WBI, but no survival difference.

  3. Timing of radiotherapy:

    • Safe to delay until after chemotherapy (International Breast Cancer Study Group VI-VII trial).
    • Concurrent use with endocrine or anti-HER2 therapy is feasible (CO-HO-RT and N9831 trials).

Discussion of Evidence

Long-Term Outcomes

  • NSABP B-06 Trial: 20-year follow-up of 1,851 patients showed equivalent survival between mastectomy, BCS alone, and BCS + radiotherapy. However, BCS without radiotherapy had a 39.2% local recurrence rate vs. 14.3% with radiotherapy.
  • Milan I Trial: Compared radical mastectomy (n=349) vs. BCS + radiotherapy (n=352). At 20 years, overall survival was identical (58.3% vs. 58.8%), but local recurrence was higher in the BCS group (8.8% vs. 2.3%).

Chinese Data

  • Li et al. (2004): 95 patients with Stage I/II breast cancer had a 2-year local recurrence rate of 1.4% post-BCS.
  • Chen et al. (2018): Propensity-matched analysis of 2,866 patients showed comparable 5-year survival between BCS and mastectomy (94.1% vs. 92.5%).

Neoadjuvant Chemotherapy

Neoadjuvant chemotherapy increases BCS eligibility for Stage III or >T2 tumors. The Early Breast Cancer Trialists’ Collaborative Group meta-analysis reported a 10-year local recurrence rate of 15.1% vs. 11.9% (P=0.10) for neoadjuvant vs. adjuvant chemotherapy, with no survival difference.

Controversies and Considerations

  • Risk factors for local recurrence: Central tumor location, nipple discharge, multifocal disease, age <35 years. These were not classified as contraindications due to insufficient evidence.
  • Margin assessment tools: Intraoperative gross inspection, imprint cytology, and specimen imaging were noted but not recommended due to lack of high-level evidence.

Conclusion

The CSBrS 2021 guidelines reinforce BCS as a safe and effective option for early-stage breast cancer, provided strict criteria for patient selection, surgical technique, and adjuvant therapy are followed. The emphasis on margin assessment, individualized radiotherapy, and integration of oncoplastic techniques reflects a balance between oncologic safety and quality of life.

doi.org/10.1097/CM9.0000000000001518

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