What are the diagnosis and treatment options for phyllodes tumors?

Phyllodes Tumor: Diagnosis and Treatment

Diagnosis

All phyllodes tumors require surgical excision with tumor-free margins of ≥1 cm, regardless of subtype (benign, borderline, or malignant), and axillary staging should NOT be performed. 1

Clinical Presentation

• Rapidly enlarging, painless breast mass is the hallmark presentation, typically occurring in women in their 40s (older than fibroadenoma patients but younger than invasive breast cancer patients) 1
• Clinical suspicion should be high for any palpable mass that is large (>2 cm) or demonstrates rapid growth 2, 1
• Patients with Li-Fraumeni syndrome (germline p53 mutation) have increased risk 1

Imaging Characteristics

• Phyllodes tumors appear identical to fibroadenomas on ultrasound and mammography, making preoperative distinction extremely difficult 1
• Lobulated shape is most common (60%), followed by oval (20%), round (4%), and irregular (3%) morphology 3
• In any large (>2 cm) or rapidly enlarging clinical "fibroadenoma," proceed directly to excisional biopsy to pathologically exclude phyllodes tumor 1

Tissue Diagnosis Pitfalls

• Fine needle aspiration (FNA) will NOT distinguish fibroadenoma from phyllodes tumor 2
• Core needle biopsy may NOT reliably distinguish fibroadenoma from phyllodes tumor in most cases 2, 4
• Excisional biopsy (complete mass removal without intent of obtaining wide surgical margins initially) is required for definitive diagnosis 2

Surgical Treatment

Primary Excision

• Wide excision with surgical margins ≥1 cm is the definitive treatment for all phyllodes tumor subtypes (benign, borderline, and malignant) 2, 1, 5
• Lumpectomy or partial mastectomy is the preferred surgical approach 1
• Total mastectomy is necessary ONLY if negative margins cannot be obtained with breast-conserving surgery 1, 4
• Mastectomy is indicated for large lesions where adequate margins cannot be achieved 5

Critical Surgical Principle

• Surgical axillary staging or lymph node dissection is NOT necessary because phyllodes tumors rarely metastasize to axillary lymph nodes 2, 1, 4, 5
• This avoids unnecessary morbidity without compromising outcomes 1

Margin Status and Recurrence

• Margin status is more important than histologic subtype for predicting local recurrence 1, 6
• Local recurrence correlates directly with excision margins (p<0.05), not with tumor grade or size 5
• Borderline and malignant phyllodes tumors with positive or ≤1 mm surgical margins have increased risk of recurrence 6
• In one series, 10 of 11 locally recurrent tumors had positive margins or ≤1 mm margins at initial surgery 6
• After re-excision with 1-cm margins, patients remained free of recurrence 5

Adjuvant Therapy

Radiotherapy

• Radiotherapy is NOT routinely recommended for all phyllodes tumors 1
• Consider radiotherapy ONLY for:
  • Borderline or malignant tumors >5 cm in size 1, 4
  • Infiltrative margins 1, 4
  • Cases where clear margins could not be achieved despite re-excision attempts 1, 4
  • Local recurrence, especially if additional recurrence would create significant morbidity (e.g., chest wall recurrence after salvage mastectomy) 2, 1
• Radiotherapy improves local control but not survival in breast sarcomas 4

Systemic Therapy

• Neither chemotherapy nor endocrine therapy has any proven role in phyllodes tumor treatment 1, 4
• Although 58% contain estrogen receptors and 75% contain progesterone receptors, endocrine therapy does not reduce recurrence or death 1
• No evidence shows adjuvant cytotoxic chemotherapy reduces recurrence or death 1
• Chemotherapy for metastatic disease should follow principles for soft tissue sarcoma, not breast adenocarcinoma 5

Reconstruction Considerations

• Immediate reconstruction should be avoided in borderline phyllodes tumors with high-risk features 1, 4
• Delayed reconstruction is preferred after primary oncological management is completed and local recurrence risk has diminished 1, 4

Management of Recurrence

Local Recurrence

• Re-excision with wide tumor-free surgical margins (≥1 cm) without axillary staging is recommended 2, 1, 4
• Consider postoperative radiation therapy if additional recurrence would create significant morbidity 2, 1, 4
• Local recurrence occurs in approximately 15% of patients overall and is more common after incomplete excision 7
• Repeated local recurrence can occur without development of distant metastases or reduced survival 7

Distant Metastases

• Most distant recurrences occur in the lung 1
• Approximately 20% of patients with malignant phyllodes tumors develop distant metastases 7
• Metastatic disease should be managed following principles of soft tissue sarcoma per NCCN Guidelines 2, 1
• Long-term survival with distant metastases is rare 7

Prognostic Factors

• Histologic subtype is the only independent prognostic factor, with 5-year disease-free survival rates of 95.7% for benign, 73.7% for borderline, and 66.1% for malignant tumors 1
• However, margin status remains more important than subtype for predicting local recurrence 1
• Younger age and malignant histology are the two highest risk factors for recurrence 3

Multidisciplinary Management

• Borderline and malignant phyllodes tumors should be referred to specialist sarcoma centers for pathology review and multidisciplinary team discussion 1, 4
• Close collaboration between breast cancer and sarcoma multidisciplinary teams is necessary for appropriate risk stratification and treatment planning 4

Critical Clinical Pitfalls to Avoid

• Do NOT rely on core needle biopsy or FNA to exclude phyllodes tumor in a rapidly growing or large breast mass 2, 1, 4
• Do NOT perform routine axillary staging—this adds unnecessary morbidity without benefit 2, 1, 4, 5
• Do NOT use adjuvant chemotherapy or endocrine therapy—these have no proven efficacy 1, 4
• Do NOT routinely recommend radiotherapy for all phyllodes tumors—reserve for high-risk cases only 1, 4
• Do NOT accept inadequate surgical margins (<1 cm)—this is the most important modifiable factor for preventing local recurrence 1, 5, 6