Phyllodes tumors (PT) are rare breast malignancies accounting for 0.5% to 1% of all breast tumors. PT have unpredictable behavior, with recurrence rates as high as 40%. A dearth of information exists about racial differences; elucidation of these differences is the objective of this study.

A retrospective review of patients treated for PT at either Moffitt Cancer Center or University of Texas Health Science Center San Antonio from 1999 to 2010.

Of the 124 patients, 71 (57%) were treated at Moffitt Cancer Center and 53 (42%) at University of Texas Health Science Center San Antonio. Mean age at diagnosis was 44 years (15 to 70 years). Thirty-three patients required mastectomy. Combining both cohorts, 42% of the patients were Caucasian, 43% were Hispanic, and 12% were black. Tumors were benign in 49% patients, borderline in 35%, and malignant in 16%, with a higher percentage of borderline and malignant tumors in Hispanic patients (p < 0.01). Hispanic patients tended to have larger tumors and higher mitotic rates (p = 0.01; p = 0.03). At a median follow-up time of 13 months, the local recurrence rate (6.4%) was associated with tumor size, tumor grade, mitotic rate, and close margin status (<2 mm) (p <0.01; p = 0.01; p = 0.01; p = 0.04). However, these findings did not translate into a survival difference by race.

In this multi-institutional review of PT we found substantial pathologic differences by race with higher-grade tumors present more often in Hispanic patients. These differences did not substantially affect outcomes at short-term follow-up. Further investigation into additional molecular, biologic factors, geographic impact, and socioeconomic factors is needed to more clearly delineate this finding.