PURPOSE: To better identify prognostic factors for local control and survival, as well as the role of different therapeutic options, for phyllodes tumors, a rare fibroepithelial neoplasm of the breast. METHODS AND MATERIALS: Data from 443 women treated between 1971 and 2003 were collected from the Rare Cancer Network. The median age was 40 years (range, 12-87 years). Tumors were benign in 284 cases (64%), borderline in 80 cases (18%), and malignant in 79 cases (18%). Surgery consisted of breast-conserving surgery (BCS) in 377 cases (85%) and total mastectomy (TM) in 66 cases (15%). Thirty-nine patients (9%) received adjuvant radiotherapy (RT). RESULTS: After a median follow-up of 106 months, local recurrence (LR) and distant metastases rates were 19% and 3.4%, respectively. In the malignant and borderline group (n = 159), RT significantly decreased LR (p = 0.02), and TM had better results than BCS (p = 0.0019). Multivariate analysis revealed benign histology, negative margins, and no residual disease (no RD) after initial treatment and RT delivery as independent favorable prognostic factors for local control; benign histology and low number of mitosis for disease-free survival; and pathologic tumor size < or = 3 cm and no tumor necrosis for overall survival. In the malignant and borderline subgroup multivariate analysis TM was the only favorable independent prognostic factor for disease-free survival. CONCLUSIONS: This study showed that phyllodes tumor patients with no RD after treatment have better local control. Benign tumors have a good prognosis after surgery alone. In borderline and malignant tumors, TM had better results than BCS. Thus, in these forms adjuvant RT should be considered according to histologic criteria.