Phyllodes tumours (PT) are biphasic breast neoplasms with both stromal and epithelial components. They are classified into three groups — benign, borderline, and malignant — each with distinct biological behaviour and management implications. This page covers the borderline subgroup, which accounts for roughly 12–26% of all PT cases.
Borderline phyllodes tumour occupies the intermediate category between clearly benign and overtly malignant PT. Its classification influences decisions around surgery, margins, and whether adjuvant treatment should be considered — particularly in cases where certain histological or clinical risk features are present.
In the majority of borderline PT, surgery alone is the primary strategy. However, adjuvant radiotherapy may be considered for a specific subset of high-risk cases — for example, those with large tumours, infiltrative borders, or where adequate surgical margins cannot be achieved.
Full eligibility criteria, dose selection, fractionation options, and the complete decision algorithm are available in the structured protocol below.