What is the recommended follow‑up schedule and imaging for an adult woman after mastectomy for a borderline‑grade phyllodes tumor of the breast?

Follow-Up After Mastectomy for Borderline Phyllodes Tumor

After mastectomy for borderline phyllodes tumor, perform clinical examination every 3-6 months for the first 2-3 years, then annually, with annual chest imaging (chest X-ray or CT) to monitor for pulmonary metastases, which are the most common site of distant recurrence. 1, 2

Clinical Surveillance Schedule

• Conduct clinical examinations every 3-4 months for the first 2 years, then every 6 months for years 3-5, and annually thereafter 3, 1
• Focus physical examination on the chest wall and mastectomy scar to detect local recurrence, which occurs in approximately 1-2% annually 3
• Local recurrence is the primary concern after mastectomy for borderline phyllodes tumors, occurring in up to 24% of patients with borderline/malignant disease 4

Imaging Strategy

Chest Wall Surveillance

• Routine imaging of the mastectomy site is NOT recommended in asymptomatic patients 3
• Clinical examination is the mainstay for detecting chest wall recurrence 3
• If a palpable abnormality develops, ultrasound or MRI of the chest wall can be performed to characterize the finding 3

Pulmonary Surveillance

• Annual chest imaging (chest X-ray or low-dose chest CT) should be performed to monitor for lung metastases, as phyllodes tumors are sarcomas that metastasize hematogenously, most commonly to the lungs 1, 2
• This differs from standard breast cancer follow-up, where routine imaging for metastases is not recommended 3

Contralateral Breast Surveillance

• Perform annual mammography (2-D or digital breast tomosynthesis) with ultrasound of the contralateral breast 3
• This follows standard breast cancer screening guidelines for the remaining native breast 3

What NOT to Do

• Do NOT perform axillary or regional lymph node imaging, as phyllodes tumors rarely metastasize to lymph nodes (<1% incidence) 1, 2, 5
• Do NOT use PET-CT or bone scans for routine surveillance in asymptomatic patients 3
• Do NOT treat this as epithelial breast cancer—phyllodes tumors require sarcoma-directed surveillance principles 1, 6

Management of Recurrence

Local Recurrence

• Re-excise with wide margins (≥1 cm) without axillary staging 1, 5
• Consider postoperative radiation therapy after re-excision, especially if additional recurrence would create significant morbidity 1, 7
• Radiation therapy improves local control from 34-42% to 90-100% at 5 years in borderline/malignant phyllodes tumors 1, 7

Distant Metastases

• Prioritize surgical resection or local ablative therapy of metastatic lesions when feasible 2, 6
• If surgery is not feasible, systemic chemotherapy should follow soft tissue sarcoma treatment paradigms (doxorubicin-ifosfamide), NOT breast cancer regimens 6

Critical Clinical Pitfalls

• Borderline phyllodes tumors have a 5-year disease-free survival of approximately 66-68%, significantly lower than benign variants 2, 7
• Tumor size >5 cm, mitotic rate ≥10/10 HPF, and stromal overgrowth predict recurrence, even after mastectomy 4
• Younger age is a risk factor for recurrence 8
• Endocrine therapy and standard breast cancer chemotherapy have no proven efficacy and should not be used 1, 6

Reconstruction Considerations

• If reconstruction was not performed at the time of mastectomy, delay reconstruction until at least 2 years post-treatment when local recurrence risk has diminished 1, 2
• This allows completion of surveillance during the highest-risk period for local recurrence 2