What is the primary treatment for a Phyllodes tumor?

Primary Treatment for Phyllodes Tumor

Wide excision with surgical margins ≥1 cm is the definitive primary treatment for all phyllodes tumors (benign, borderline, and malignant), without axillary staging. 1, 2, 3

Surgical Approach

Margin Requirements

• Target surgical margins of ≥1 cm to minimize local recurrence risk 1, 2, 3
• Narrow margins (<1 cm) are strongly associated with local recurrence—in one series, all 5 local recurrences occurred in patients with positive or <1 cm margins 4
• Margin width is more important than histologic subtype for predicting local recurrence 3
• If initial excision yields inadequate margins, re-excision to achieve ≥1 cm margins is mandatory 1, 5

Breast Conservation vs. Mastectomy

• Breast-conserving surgery (wide local excision) is the preferred approach for most phyllodes tumors 1, 3
• Mastectomy is indicated only when adequate margins cannot be achieved with breast conservation 1, 3
• Large tumor size alone (even >5 cm) does not mandate mastectomy if clear margins are achievable 6, 5
• The extent of surgery (mastectomy vs. wide excision) does not affect disease-free survival when adequate margins are obtained 7

What NOT to Do Surgically

• Do not perform axillary staging or sentinel lymph node biopsy—phyllodes tumors rarely metastasize to lymph nodes 1, 3
• Do not accept simple enucleation or excisional biopsy without adequate margins—this leads to high recurrence rates 5
• Avoid immediate reconstruction in large, high-grade tumors; delayed reconstruction is preferred after completing oncologic treatment and reducing recurrence risk 1, 2

Adjuvant Radiotherapy

When to Consider Radiation

Radiotherapy is not routinely recommended for all phyllodes tumors 3. Consider adjuvant radiation only in specific high-risk scenarios:

• Borderline or malignant tumors >5 cm 1, 2
• Close margins (<5 mm) or positive margins when re-excision is not feasible 1
• Infiltrative margins 1, 2
• Locally recurrent disease, especially when additional recurrence would create significant morbidity (e.g., chest wall recurrence after salvage mastectomy) 1, 2

Evidence Limitations

• No prospective randomized data support routine radiation for phyllodes tumors 1
• Radiation improves local control but not survival 1, 3

Systemic Therapy

Neither chemotherapy nor endocrine therapy has any proven role in phyllodes tumor treatment 3:

• Despite 58% containing estrogen receptors and 75% containing progesterone receptors, endocrine therapy does not reduce recurrence or death 3
• No evidence shows adjuvant cytotoxic chemotherapy reduces recurrence or death 3
• For metastatic disease, follow soft tissue sarcoma treatment principles, not breast adenocarcinoma protocols 1, 4

Diagnostic Pitfalls

Preoperative Challenges

• Core needle biopsy and fine needle aspiration often cannot distinguish phyllodes tumors from fibroadenomas 1, 3
• Clinical suspicion should be raised for: palpable mass with rapid growth, large size (>2 cm), or imaging suggesting fibroadenoma but with atypical size/growth history 1
• Excisional biopsy is required for any rapidly enlarging or large (>2 cm) "fibroadenoma" to pathologically exclude phyllodes tumor 3

Management of Recurrence

• Re-excision with wide margins (≥1 cm) without axillary staging for local recurrence 1, 2
• Consider postoperative radiation if additional recurrence would create significant morbidity 1, 2
• Most distant metastases occur in the lung and should be managed according to soft tissue sarcoma guidelines 3

Multidisciplinary Coordination

• Borderline and malignant phyllodes tumors should be referred to specialist sarcoma centers for pathology review and multidisciplinary team discussion 1, 2
• Close collaboration between breast cancer and sarcoma multidisciplinary teams is necessary for optimal risk stratification and treatment planning 1, 2

Prognosis by Histologic Grade

• 5-year disease-free survival: 95.7% for benign, 73.7% for borderline, 66.1% for malignant 3
• However, margin status trumps histologic subtype for predicting local recurrence 3, 7
• Tumor features predicting worse outcomes include: size >5 cm, mitotic rate ≥10/10 HPF, stromal overgrowth, and high stromal cellularity 7