What are the treatment options for benign, borderline (moderate), and malignant phyllodes tumors?

Treatment Options for Phyllodes Tumors of the Breast

Wide local excision with ≥1 cm margins is the standard treatment for all phyllodes tumors (benign, borderline, and malignant), with mastectomy reserved for cases where negative margins cannot be achieved with breast conservation. 1

Classification and General Approach

Phyllodes tumors are classified into three categories based on histopathological features:

• Benign
• Borderline (moderate)
• Malignant

Initial Diagnostic Workup

• History and physical examination
• Ultrasound
• Mammogram (for women ≥30 years)
• Core needle biopsy 1

Treatment by Classification

Benign Phyllodes Tumors

• Primary treatment: Wide local excision with ≥1 cm margins 1
• No axillary staging needed as lymph node involvement is rare 1
• No adjuvant therapy required after margin-negative resection 2
• Excellent prognosis with low recurrence rates when adequate margins are achieved 2

Borderline Phyllodes Tumors

• Primary treatment: Wide local excision with ≥1 cm margins 1
• Re-excision recommended if margins are positive or narrow (<1 cm) 1
• Consider adjuvant radiation therapy for:
  • Large tumors (>5 cm)
  • Close (<5 mm) or positive margins that cannot be re-excised
  • Infiltrative margins
  • Multifocal or recurrent disease 3, 1
• Adjuvant radiation significantly improves local recurrence-free survival (90% vs 42% at 5 years) 2

Malignant Phyllodes Tumors

• Primary treatment: Wide local excision with ≥1 cm margins or mastectomy if negative margins cannot be achieved 3, 1
• No axillary staging required unless nodes are clinically positive 1
• Adjuvant radiation therapy strongly recommended for:
  • All malignant phyllodes tumors, especially large tumors (>5 cm)
  • Close (<5 mm) or positive margins
  • Multifocal or recurrent disease 3, 1, 2
• Breast reconstruction should be considered as a delayed rather than immediate procedure, particularly for large tumors that may require postoperative radiation 3
• For metastatic disease, treatment should follow protocols for soft tissue sarcoma 1

Important Considerations for Surgical Management

• Margin status is critical for local control, with positive or narrow margins (<1 mm) significantly increasing recurrence risk 4
• Tumor features predictive of recurrence include:
  • Size >5 cm
  • Mitotic rate ≥10/10 HPF
  • Stromal overgrowth
  • High cellularity 5
• Mastectomy should be considered only if negative margins cannot be achieved with breast conservation 1

Role of Adjuvant Therapies

Radiation Therapy

• Significantly improves local control but not overall survival 3
• Most beneficial for borderline and malignant tumors 2
• For patients treated with margin-negative breast-conserving surgery, 5-year local recurrence-free survival is 100% with RT vs 34.3% without RT 2

Chemotherapy and Hormonal Therapy

• Adjuvant chemotherapy has no proven role in reducing recurrence or mortality 1
• Despite high ER/PR expression in some tumors, endocrine therapy has no established role 1

Follow-up and Surveillance

• Regular surveillance is essential as most recurrences occur within the first few years 1
• For recurrent disease:
  • Re-excision with wide margins without axillary staging
  • Consider postoperative radiation for recurrent cases 1

Common Pitfalls and Caveats

• Diagnostic challenges: Core needle biopsy and FNA are often inadequate to distinguish phyllodes tumors from fibroadenomas 1
• Surgical margins: Traditional teaching recommended ≥10 mm margins, but recent evidence suggests that narrower negative margins may be sufficient for benign phyllodes tumors 4
• Borderline tumors: These have an unexpectedly high recurrence risk and should be treated more aggressively than their classification might suggest 6
• Delayed reconstruction: Consider delaying breast reconstruction after mastectomy for large malignant tumors due to potential need for postoperative radiation and risk of early recurrence 3