Phyllodes tumors of the breast: The British Columbia Cancer Agency experience

Phyllodes tumors of the breast are uncommon fibroepithelial lesions for which optimal management remains unclear. This retrospective population-based study reports treatment and outcomes for patients with phyllodes tumors and evaluates characteristics that influence outcome.

Data were analysed on 183 patients with newly diagnosed phyllodes tumors from 1999 to 2014. Five-year Kaplan-Meier local recurrence and survival were compared between cohorts with benign (n=83), borderline (n=50) and malignant phyllodes tumor (n=49) histology.

Median (range) follow-up was 65 (0.5-197) months. Local excision was performed in 163 and mastectomy in 19 patients. Eleven patients with malignant phyllodes tumors received radiation therapy. Overall, local recurrence occurred in 8.7%, distant metastases in 4.4%, and cause specific deaths in 3.8%. Five-year Kaplan-Meier outcomes among women with benign, borderline, and malignant phyllodes tumors were: local recurrence 6% vs 9% vs 21%, P=0.131; overall survival 96% vs 100% vs 82%, P=0.002; and disease-free survival 94% vs 91% vs 67%, P<0.001. Five-year Kaplan-Meier local recurrence among women with negative vs close vs positive margins were 8% vs 6% vs 37%, P<0.001. Corresponding rates for intermediate vs pushing vs infiltrative borders were 6% vs 6% vs 33%, P=0.006. Positive margins and infiltrative tumor borders were associated with increased local recurrence (all P≤0.006), and the latter remained significant in exploratory analyses after adjusting for margin status and phyllodes tumor classification.

Five-year outcomes among women with phyllodes tumors were comparable to those reported in the literature. Exploratory analysis has suggested that infiltrative tumor borders may be used in conjunction with margin status to assess local recurrence risk.