title: Ipsilateral breast tumour recurrence (IBTR) dynamics in breast conserving treatments with or without radiotherapy.
abstract: OBJECTIVE
  To study whether ipsilateral breast tumour recurrence (IBTR) dynamics are modified by post-operative radiotherapy (RT).
  
  
  METHODS
  The hazard rate for IBTR was analysed in a database from patients undergoing breast conserving surgery with or without post-operative radiotherapy within randomised clinical trials from the Milan Cancer Institute.
  
  
  RESULTS
  The hazard rate for IBTR presents a bimodal pattern. Post-operative radiotherapy, in addition to reducing IBTR incidence from 24.5% to 5.8% at 10 years, causes more than a one year delay in its clinical manifestation. Distant metastasis dynamics are not modified by radiotherapy administration.
  
  
  CONCLUSIONS
  In the light of a biology-based model of breast cancer metastasis development, IBTR peak delay most likely originates in a more prolonged dormancy time that, in turn, is related to local microenvironment conditions. Present clinical findings suggest that, besides a direct killing effect on residual tumour cells, microenvironmental modifications may play a major role in RT effectiveness.
authors.affiliation: Department of Medical Oncology, Università di Milano, Milano, Italy. demicheli@istitutotumori.mi.it
authors.forename: Romano
authors.initials: R
authors.lastname: Demicheli
authors.forename: Ilaria
authors.initials: I
authors.lastname: Ardoino
authors.forename: Patrizia
authors.initials: P
authors.lastname: Boracchi
authors.forename: Laura
authors.initials: L
authors.lastname: Lozza
authors.forename: Elia
authors.initials: E
authors.lastname: Biganzoli
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis / Q000473:pathology; D009364:Neoplasm Recurrence, Local / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D009367:Neoplasm Staging; D018714:Radiotherapy, Adjuvant; D016032:Randomized Controlled Trials as Topic; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome