A prospective, multi-institutional study of adjuvant radiotherapy after resection of malignant phyllodes tumors

Abstract

Background: Malignant phyllodes tumors of the breast are unusual neoplasms, with an incidence of approximately 500 cases annually in the United States. Published local recurrence rates after margin-negative breast-conserving resections of borderline malignant and malignant phyllodes tumors are unacceptably high, at 24 and 20%, respectively. It is uncertain whether radiotherapy after resection of phyllodes tumors is beneficial. Methods: We prospectively enrolled patients who were treated with a margin-negative breast-conserving resection of borderline malignant or malignant phyllodes tumors to adjuvant radiotherapy. The primary endpoint was local recurrence. Results: Forty-six women were treated at 30 different institutions. The mean patient age was 49 years (range, 18-76 years). Thirty patients (65%) had malignant phyllodes tumors; the rest were borderline malignant. The mean tumor diameter was 3.7 cm (range, .8-11 cm). Eighteen patients had a negative margin on the first excision. The median size of the negative margin was .35 cm (range,