What is the management approach for a patient with a phyllodes tumor?

Management of Phyllodes Tumor

Surgical excision with tumor-free margins of ≥1 cm is the definitive treatment for all phyllodes tumors, with breast-conserving surgery preferred when feasible and mastectomy reserved only for cases where adequate margins cannot be achieved. 1, 2

Primary Surgical Approach

Initial Excision Strategy

• Perform wide excision targeting ≥1 cm margins as the single most important factor for preventing local recurrence 1, 2
• Breast-conserving surgery (lumpectomy or partial mastectomy) is the preferred approach for all subtypes when negative margins can be achieved 1, 2
• Mastectomy is indicated only when adequate margins cannot be obtained with breast conservation, typically for very large tumors relative to breast size 1, 2
• Never perform axillary lymph node dissection or sentinel node biopsy—phyllodes tumors metastasize to lymph nodes in <1% of cases, making nodal staging unnecessary and adding only morbidity 1, 2, 3

Margin Management by Subtype

• For benign phyllodes tumors: positive margins do not require re-excision if the tumor is completely removed 1, 4
• For borderline and malignant phyllodes tumors: re-excise if margins are positive or <1 cm when feasible 1, 3, 5
• Local recurrence correlates directly with margin status—all patients with margins <1 cm or positive margins had recurrence in one series, while those re-excised to ≥1 cm margins remained recurrence-free 5

Adjuvant Radiotherapy Decision Algorithm

Indications for Radiotherapy (Borderline and Malignant Only)

Consider adjuvant radiotherapy for:

• Tumor size >5 cm 1, 2, 3
• Infiltrative margins 1
• Close margins (<5 mm) or positive margins that cannot be surgically cleared despite re-excision attempts 1, 3
• Local recurrence after salvage mastectomy where additional recurrence would create significant chest wall morbidity 1

Radiotherapy Technical Details

• Target the whole breast (after breast-conserving surgery) or chest wall (after mastectomy) to 50-60 Gy 1
• Do not include axillary, supraclavicular, or internal mammary lymph nodes—phyllodes tumors are sarcomas, not epithelial breast cancers 1
• Radiotherapy improves local control from 34-42% to 90-100% at 5 years but does not improve overall survival 1, 3
• Do not routinely recommend radiotherapy for benign phyllodes tumors or small (<5 cm) borderline tumors with clear margins 1, 2

What NOT to Do: Critical Pitfalls

Avoid Inappropriate Therapies

• Never use adjuvant chemotherapy for completely resected phyllodes tumors—it has no proven role in reducing recurrence or death 2, 3
• Never prescribe tamoxifen, aromatase inhibitors, or other endocrine therapy—these have no efficacy despite hormone receptor positivity 2
• Never use breast cancer chemotherapy regimens for phyllodes tumors—if systemic therapy is needed for metastatic disease, use sarcoma-directed regimens like Doxorubicin-Ifosfamide 2, 5

Avoid Inappropriate Staging

• Never perform axillary staging—it adds morbidity without benefit 1, 2, 3

Reconstruction Timing

• Avoid immediate reconstruction in borderline or malignant phyllodes tumors with high-risk features (>5 cm, infiltrative margins) 1, 3
• Delay reconstruction until after radiotherapy completion and when local recurrence risk has diminished, typically 2 years post-treatment 1, 3

Management of Recurrent Disease

Local Recurrence

• Re-excise with wide margins (≥1 cm) without axillary staging 1
• Consider postoperative radiotherapy, especially if additional recurrence would create significant morbidity or if not previously given 1

Metastatic Disease

• Prioritize surgical resection or local ablative therapy of metastatic lesions as primary treatment given the relatively indolent nature of these tumors 2
• When surgery is not possible or after disease progression, use sarcoma-directed chemotherapy regimens (not breast cancer protocols) 2
• Distant metastases occur most commonly to the lungs 3

Multidisciplinary Management

• Refer all borderline and malignant phyllodes tumors to specialist sarcoma centers for pathology review 1
• Discuss at both breast cancer and sarcoma multidisciplinary team meetings to ensure appropriate risk stratification and treatment planning 1, 3

Surveillance Strategy

• Monitor for local recurrence as the primary concern—occurs in 10-24% of patients depending on subtype and margins 6, 7
• 5-year disease-free survival: 95.7% for benign, 73.7% for borderline, and 66.1% for malignant tumors 2, 3
• Tumor size >5 cm, mitotic rate ≥10/10 HPF, stromal overgrowth, and stromal cellularity predict recurrence and survival 6

Diagnostic Pitfall

• Core needle biopsy may not reliably distinguish phyllodes tumors from benign fibroadenoma preoperatively—phyllodes tumors often mimic fibroadenomas on clinical examination and imaging 1, 5