What are the recommended margins for Phyllodes tumor resection?

Recommended Surgical Margins for Phyllodes Tumor Resection

Wide excision with surgical margins of ≥1 cm is the standard recommendation for all phyllodes tumors (benign, borderline, and malignant) to minimize local recurrence risk. 1, 2, 3, 4

Primary Surgical Approach

The goal is wide excision with tumor-free margins of at least 1 cm, which is the single most important factor for preventing local recurrence. 3, 4

• Lumpectomy or partial mastectomy is the preferred surgical approach for all phyllodes tumor subtypes 3, 4
• Total mastectomy is indicated only when negative margins of ≥1 cm cannot be achieved with breast-conserving surgery 3, 4
• Axillary lymph node dissection or sentinel node biopsy is NOT indicated because phyllodes tumors rarely metastasize to lymph nodes (<1% have positive nodes) 3, 4

Evidence on Margin Width and Recurrence

The relationship between margin width and recurrence shows important nuances:

For borderline and malignant phyllodes tumors, margins <1 mm are associated with significantly higher recurrence rates. 5 A meta-analysis demonstrated that surgical margins of 1 mm (OR: 0.4,95% CI: 0.27-0.61) and 1 cm (OR: 0.45,95% CI: 0.15-0.85) both resulted in significantly higher recurrence rates compared to wider margins 5.

However, the most recent multi-institutional study of 550 cases (2007-2017) found that wider margin width was not associated with reduced local recurrence for the entire cohort. 6 This contemporary data suggests that progressively wider surgical margins beyond a negative margin may not reduce local recurrence, particularly for benign tumors 6.

Grade-Specific Margin Recommendations

Benign Phyllodes Tumors

• A negative margin (tumor not at ink) may be sufficient for benign phyllodes tumors, and re-excision of a negative margin is not recommended regardless of margin width. 6, 7
• The traditional ≥10 mm excisional margin is not necessary for benign tumors 7
• Local recurrence rates are sufficiently low in benign phyllodes tumors that imaging can be performed based on clinical symptoms rather than routine surveillance 7

Borderline and Malignant Phyllodes Tumors

• Target surgical margins of ≥1 cm to minimize local recurrence risk. 2, 4
• Borderline and malignant phyllodes tumors with a positive or ≤1 mm surgical margin have an increased risk of recurrence 7
• Small tumors (≤5 cm) with frequent mitoses (≥10 mitoses/10 HPF) have the highest local recurrence rate (55.6%) and warrant ensuring a 1 cm margin, if necessary through second surgery 8

Management of Positive or Close Margins

If initial excision yields positive margins or margins <1 cm, re-excision should be performed for borderline and malignant tumors. 1, 2, 4

• Narrow surgical margins are associated with heightened local recurrence risk but are not an absolute indication for mastectomy when partial mastectomy fails to achieve margin width ≥1 cm 1
• In contemporary practice, 32% of patients with initially positive margins did not undergo second operation, among whom only 2.7% recurred, suggesting selective re-excision may be appropriate 6
• When re-excision is performed for positive margins, residual disease is found in only 2.9% of cases 6

Common Pitfalls to Avoid

• Do NOT accept inadequate surgical margins—this is the most important factor for preventing local recurrence. 4
• Do NOT perform routine axillary staging—this adds unnecessary morbidity without benefit. 3, 4
• Do NOT rely on core needle biopsy or FNA to exclude phyllodes tumor in a rapidly growing or large breast mass, as these may not distinguish fibroadenoma from phyllodes tumor. 1, 4

Adjuvant Radiotherapy Considerations

Radiotherapy is NOT routinely recommended for all phyllodes tumors. 3, 4

• Consider adjuvant radiotherapy only for borderline or malignant tumors >5 cm in size, infiltrative margins, or cases where clear margins could not be achieved despite re-excision attempts 2, 3, 4
• Adjuvant radiotherapy significantly reduced recurrence rate of malignant tumors (P = 0.034) but did not significantly reduce recurrence rates of overall and borderline tumors 5
• For locally recurrent disease, consider postoperative radiation therapy, especially if additional recurrence would create significant morbidity 1, 2