title: Primary treatment of cystosarcoma phyllodes of the breast.
abstract: BACKGROUND
  Cystosarcoma phyllodes is a rare sarcoma of the breast. Although surgical removal is the mainstay of treatment, the extent of surgery required (excision vs. mastectomy) and the need for additional local therapy, such as radiotherapy, are unclear. The current study evaluated the rate of local and distant failure, as well as potential prognostic factors, to better define appropriate treatment strategies.
  
  
  METHODS
  One hundred one patients treated primarily for cystosarcoma phyllodes of the breast were evaluated. These tumors were classified histologically into benign (58%), indeterminate (12%), and malignant (30%) based on well defined criteria. Stromal overgrowth (29%) was considered separately. Surgery was comprised of local excision with breast conservation (47%) or mastectomy (53%). Microscopic surgical margins were negative in 99% of cases. Six patients received adjuvant radiotherapy.
  
  
  RESULTS
  Overall survival for the 101 patients was 88%, 79%, and 62% at 5, 10, and 15 years, respectively. For patients with nonmalignant (benign or indeterminate) and malignant cystosarcoma phyllodes, the overall survival was 91% and 82%, respectively, at 5 years, and 79% and 42%, respectively, at 10 years. Similar rates were observed based on the presence or absence of stromal overgrowth. Local recurrence occurred in 4 patients, with an actuarial 10-year rate of 8%. Eight patients developed distant metastases, with an actuarial 10-year rate of 13%. Multivariate analysis using Cox proportional hazards regression revealed stromal overgrowth to be the only independent predictor of distant failure.
  
  
  CONCLUSIONS
  Local failure in this group of largely margin negative patients with cystosarcoma phyllodes of the breast was low, showing that breast-conserving surgery with appropriate margins is the preferred primary therapy. The current study data do not support the use of adjuvant radiotherapy for patients with adequately resected disease. Patients with stromal overgrowth, particularly when the tumor size was > 5 cm, were found to have a high rate of distant failure; such patients merit consideration of a trial that examines the efficacy of systemic therapy.
authors.affiliation: Division of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: A W
authors.initials: AW
authors.lastname: Chaney
authors.forename: A
authors.initials: A
authors.lastname: Pollack
authors.forename: M D
authors.initials: MD
authors.lastname: McNeese
authors.forename: G K
authors.initials: GK
authors.lastname: Zagars
authors.forename: P W
authors.initials: PW
authors.lastname: Pisters
authors.forename: R E
authors.initials: RE
authors.lastname: Pollock
authors.forename: K K
authors.initials: KK
authors.lastname: Hunt
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008408:Mastectomy; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D018365:Neoplasm, Residual; D003557:Phyllodes Tumor / Q000473:pathology / Q000601:surgery*; D011379:Prognosis; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome