Clinicopathologic features and long-term outcomes of 293 phyllodes tumors of the breast.

Background: Phyllodes tumors (PT) are rare fibroepithelial neoplasms of the breast with unpredictable behavior. We reviewed our single institution experience with PT over 51 years to identify factors predictive of local recurrence (LR) and metastasis.

Methods: From 1954 to 2005, a total of 352 cases of PT were identified; 293 had follow-up. All available pathology slides (90%) were rereviewed for margins, borders, fibroproliferation in the surrounding breast tissue, stromal pattern, stromal cellularity, frequency of mitoses, and necrosis.

Results: All cases occurred in women, with a median age of 42, with 203 originally categorized as benign and 90 as malignant. Median follow-up was 7.9 years. A total of 35 patients developed LR at a median of 2 years. In univariate analyses, a higher actuarial LR rate was associated with positive margins (P = .04), fibroproliferation (P = .001), and necrosis (P = .006). PT classified as malignant did not have a higher risk of LR (P = .79). Five patients developed distant disease at a median of 1.2 years. These patients constituted 71% of the seven patients who had uniformly aggressive pathologic features, including large tumor size (>or=7.0 cm), infiltrative borders, marked stromal overgrowth, marked stromal cellularity, high mitotic count, and necrosis.

Conclusions: Positive margins, fibroproliferation in the surrounding breast tissue, and necrosis are associated with a marked increase in LR rates. Efforts should be made to achieve negative surgical margins to reduce risk of LR. Death from PT is rare (2%), and only PT that demonstrate uniformly aggressive pathologic features seem to be associated with mortality.