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:
- 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 2020 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