Predicting Outcome in Mammary Phyllodes Tumors: Relevance of Clinicopathological Features

Phyllodes tumors (PTs) of the breast are uncommon fibroepithelial neoplasms. Most behave in a benign fashion but they also have the potential to recur locally or to metastasize.

In the current study involving 290 PTs (181 benign, 76 borderline, and 33 malignant) from three hospitals over an 11-year period, we assessed the relationship between histologic parameters (including histologic features affecting grade and surgical margin status), postoperative adjuvant treatment, and local recurrences and distant metastases.

An involved surgical margin was the only factor associated with increased risk of local recurrences (hazard ratio [HR] 4.673, p = 0.003), but not for distant metastases. For local recurrences, a wider margin did not confer additional benefits. None of the histologic factors were predictive for local recurrences. In contrast, distant metastases were correlated with histologic parameters, particularly an infiltrative border (HR 10.935, p = 0.012) and the presence of necrosis (HR 15.311, p = 0.007). In this series, all local recurrences were found in patients without radiotherapy, regardless of surgical margin status.

A negative surgical margin is mandatory for the effective local control of PT recurrence, and a minimal margin clearance may be sufficient. For distant metastases, the inherent characteristics of PTs are important, thus it may be prudent to evaluate additional histologic features, including necrosis, for patients' prognostication.