What are the diagnostic criteria and treatment options for phyllodes tumors?

Diagnostic Criteria and Treatment of Phyllodes Tumors

Phyllodes tumors are rare fibroepithelial breast neoplasms classified into benign, borderline, and malignant subtypes based on histologic features, though no uniform agreement exists on exact criteria for subtype assignment, and surgical margin status is more important than subtype for predicting recurrence. 1

Diagnostic Criteria

Clinical Presentation

• Mean age at presentation is in the 40s, occurring in an older age distribution than fibroadenomas but younger than invasive ductal/lobular cancers 1
• Rapidly enlarging, usually painless breast mass is the hallmark presentation 1
• Patients with Li-Fraumeni syndrome (germline p53 mutation) have increased risk 1

Imaging Characteristics

• Phyllodes tumors often appear identical to fibroadenomas on ultrasound and mammography, making preoperative distinction difficult 1
• Tumor size and radiological suspicion (BI-RADS category) increase with tumor grade 2
• In the setting of a large (>2 cm) or rapidly enlarging clinical "fibroadenoma," excisional biopsy should be performed to pathologically exclude phyllodes tumor 1, 3

Biopsy Limitations

• Fine needle aspiration (FNA) and core needle biopsy are inadequate to reliably distinguish phyllodes tumors from fibroadenoma 1
• Core needle biopsy has overall sensitivity of only 71.83%, with sensitivity decreasing from benign (56.81%) to malignant (37.5%) subtypes 2
• Diagnosis before excisional biopsy/lumpectomy is uncommon 1

Histologic Classification Criteria

While no uniform agreement exists, tumors are classified based on: 1, 4

• Tumor margin characteristics (pushing vs. infiltrative)
• Stromal cellularity (increases with grade)
• Mitotic count (increases with grade)
• Cellular atypia (increases with grade)
• Presence of stromal overgrowth
• Tumor necrosis (associated with malignant subtype)

Treatment Algorithm

Primary Surgical Management

All phyllodes tumors (benign, borderline, and malignant) require surgical excision with tumor-free margins of ≥1 cm. 1, 5

Surgical Options:

• Lumpectomy or partial mastectomy is the preferred surgical therapy 1, 5
• Total mastectomy is necessary ONLY if negative margins cannot be obtained with breast-conserving surgery 1, 5
• Wide local excision with adequate margins is the preferred initial therapy, with 98.7% cure rate for benign tumors and 80% for borderline tumors 4

Axillary Management:

• Surgical axillary staging or lymph node dissection is NOT necessary because phyllodes tumors rarely metastasize to axillary lymph nodes 1, 5
• Axillary surgery should be performed ONLY if lymph nodes are pathologically enlarged on clinical examination 1

Adjuvant Radiotherapy

Radiotherapy is NOT routinely recommended for all phyllodes tumors. 5

Consider radiotherapy ONLY for:

• Borderline or malignant tumors >5 cm in size 5
• Infiltrative margins 5
• Cases where clear margins could not be achieved despite re-excision attempts 5
• Local recurrence, especially if additional recurrence would create significant morbidity 5

Important caveat: Some panel members recommend radiation after local recurrence resection, but this remains controversial (category 2B recommendation) 1

Adjuvant Systemic Therapy

Neither chemotherapy nor endocrine therapy has any proven role in phyllodes tumor treatment. 1, 5

• Although 58% contain ER and 75% contain PR, endocrine therapy does not reduce recurrence or death 1
• No evidence shows adjuvant cytotoxic chemotherapy reduces recurrence or death 1

Management of Recurrence

Local Recurrence (occurs in ~15% of patients, more common after incomplete excision): 6, 7

• Re-excision with wide tumor-free surgical margins 1, 5
• Consider postoperative radiation therapy if additional recurrence would create significant morbidity 5
• Local recurrence occurs most commonly in the breast/chest wall 1

Distant Recurrence (occurs in ~20% of malignant phyllodes): 6

• Most distant recurrences occur in the lung (may be solid nodules or thin-walled cavities) 1
• Treat according to NCCN Guidelines for Soft Tissue Sarcoma 1

Reconstruction Considerations

• Immediate reconstruction should be avoided in borderline phyllodes with high-risk features 5
• Delayed reconstruction is preferred after primary oncological management is completed and local recurrence risk has diminished 5

Prognostic Factors

Histologic subtype is the only independent prognostic factor: 4

• 5-year disease-free survival: 95.7% for benign, 73.7% for borderline, 66.1% for malignant 4
• However, margin status is more important than subtype for predicting local recurrence 1

Critical Clinical Pitfalls to Avoid

1. Do NOT rely on core needle biopsy or FNA to exclude phyllodes tumor in a rapidly growing or large breast mass 1, 2

2. Do NOT perform routine axillary staging - this adds unnecessary morbidity without benefit 1, 5

3. Do NOT use adjuvant chemotherapy or endocrine therapy - these have no proven efficacy 1, 5

4. Do NOT routinely recommend radiotherapy for all phyllodes tumors - reserve for high-risk cases only 5

5. Do NOT accept inadequate surgical margins - this is the most important factor for preventing local recurrence 1, 5

Multidisciplinary Management

Borderline and malignant phyllodes tumors should be referred to specialist sarcoma centers for pathology review and multidisciplinary team discussion 5