Phyllodes tumors (PT), previously known as cystosarcoma phyllodes, were first described  by Johannes Muller in 1838, and  account for 0.5% to 1.0% of all breast tumors and 2.5% of all fibroepithelial tumors. It is composed by epithelial and mesenchymal elements , the latter giving it the  neoplastic features, in the opposite of the remaining invasive breast adenocarcinoma deriving from epithelial set.

Due to the low prevalence of phyllodes breast tumors, it is still relatively understudied with regards to etiologic risk factors, and treatment modalities especially in the Middle East Region. Therefore, the aim of this study is to describe demographic and clinical data along with outcomes in phyllodes breast tumor patients administrated at the AUBMC. 

Patients with a histologically or radiologically proven phyllodes breast tumor.

This study will be a single institution retrospective cohort study based on chart review of all cases of phyllodes breast tumor seen at the American University of Beirut Medical Center (AUBMC), a tertiary- care hospital, over a period of 10  years (January 1st of 2005 until December 18^th 2015).

A list with the names of these patients will be obtained from the institutional tumor registry at AUBMC. Given we are studying a relatively rare exposure; the best feasible study design would be a retrospective cohort study.