Phyllodes Tumors of the Breast

• Phyllodes tumors of the breast:
  • Are rare lesions
• Phyllodes tumors are classified into three groups:
  • Benign
  • Borderline
  • Malignant
• Borderline and malignant phyllodes tumors:
  • Have a higher incidence of local recurrence:
    • Therefore, historically management was:
      • A mastectomy without nodal assessment
    • Recently, more patients are undergoing lumpectomy for this lesion
    • Researchers believe that local recurrence rates:
      • Are similar for borderline and malignant phyllodes tumors:
• • Historically:
    • 1 cm margins have been recommended for malignant and borderline phyllodes tumors:
      • And continue to be recommended in the current 2023 NCCN guidelines
    • The guidelines however note that while narrow margins are associated with an increased risk for local recurrence:
      • They are not an absolute indication for mastectomy
  • Newer data may suggest a smaller margin is adequate:
    • Spanheimer et al^:
      • Identified local recurrences in 16% of 71 patients with borderline or malignant phyllodes tumors undergoing:
        • Breast-conserving surgery
      • Some of these patients had a positive or close (< 1 mm) margin
      • When the subset of patients with a margin > 1 mm was considered:
        • The local recurrence rate was 12%
  • In addition, radiation may play a role in decreasing the risk of local recurrence:
    • In a prospective, multi-institutional study, 46 patients (30 with malignant phyllodes tumors and 16 with borderline phyllodes tumors) underwent margin-negative resections followed by radiation therapy:
      • Eight of these patients had margins < 2 mm
      • After 10 years of observation for all patients:
        • None had developed a local recurrence
    • In another study using data from the National Cancer Database, Gnerlich et al:
      • Showed that adjuvant radiation therapy decreased the risk of local recurrence after resection of phyllodes tumors by:
        • More than half (hazard ratio [HR] 0.43, 95% confidence interval [CI] 0.19–0.95).⁴
• References
  • Tan, BY, Acs, G, Apple, SK, et al. Phyllodes tumor of the breast: a consensus review. Histopathology. 2016;68(1):5-21.
  • Spanheimer P, Murray M, Zabor E, et al. Long term outcomes after surgical treatment of malignant/borderline phyllodes tumors of the breast. Ann Surg Oncol. 2019;26(7):2136-2143.
  • Barth R, Wells W, Mitchell S, Cole B. A prospective, multi-institutional study of adjuvant radiation therapy after resection of malignant phyllodes tumors. Ann Surg Oncol. 2009;16(8):2288-2294.
  • Gnerlich J, Williams R, Yao K, Jaskowiak N, Kulkarni S. Utilization of radiotherapy for malignant phyllodes tumors: analysis of the National Cancer Database 1998–2009. Ann Surg Oncol. 2014;21(4):1222-1230

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