title: Randomized clinical trial to assess the effectiveness of breast irradiation following lumpectomy and axillary dissection for node-negative breast cancer.
abstract: BACKGROUND
  Although the conservation management of breast cancer has become a routine method of treatment in most centers, there is still considerable controversy surrounding the ultimate minimum treatment required for node-negative breast cancer to achieve adequate local control.
  
  
  OBJECTIVE
  Our purpose was to assess the value of breast irradiation in reducing breast relapse following conservation surgery for node-negative breast cancer. We attempted to define low-risk groups of women for breast and distant site relapse (i.e., recurrence outside the breast) who might be spared breast irradiation or adjuvant systemic therapy.
  
  
  METHODS
  Eight hundred thirty-seven patients were randomly assigned to receive radiation therapy or no radiation therapy following lumpectomy and axillary dissection for node-negative breast cancer.
  
  
  RESULTS
  Breast irradiation reduced relapse in the breast from 25.7% in the controls to 5.5% in the irradiated patients. There was no difference in survival between the two groups (median follow-up, 43 months). A low-risk group (less than 5% chance of relapse in the breast without irradiation) could not be defined. Tumor size (greater than 2 cm), age (less than 40 years), and poor nuclear grade were important predictors for breast relapse. Age (less than 50 years) and poor nuclear grade were important predictors for mortality. The presence of ductal carcinoma in situ did not predict breast relapse.
  
  
  CONCLUSIONS
  Breast irradiation significantly reduces breast relapse, but it does not influence survival. Important predictors of breast relapse are age, tumor size, and nuclear grade, but not the presence of ductal carcinoma in situ. Age and, in particular, nuclear grade predict survival.
  
  
  CONCLUSIONS
  Further follow-up may define an acceptable low-risk group for breast relapse. Until then, we recommend that all patients receive breast irradiation. Systemic adjuvant therapy should be considered for patients with poor nuclear grade tumors.
authors.affiliation: Ontario Cancer Institute/Princess Margaret Hospital, Toronto, Canada.
authors.forename: R M
authors.initials: RM
authors.lastname: Clark
authors.forename: P B
authors.initials: PB
authors.lastname: McCulloch
authors.forename: M N
authors.initials: MN
authors.lastname: Levine
authors.forename: M
authors.initials: M
authors.lastname: Lipa
authors.forename: R H
authors.initials: RH
authors.lastname: Wilkinson
authors.forename: L J
authors.initials: LJ
authors.lastname: Mahoney
authors.forename: V R
authors.initials: VR
authors.lastname: Basrur
authors.forename: B D
authors.initials: BD
authors.lastname: Nair
authors.forename: R S
authors.initials: RS
authors.lastname: McDermot
authors.forename: C S
authors.initials: CS
authors.lastname: Wong
mesh_terms: D000367:Age Factors; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery / Q000628:therapy*; D002278:Carcinoma in Situ / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000601:surgery; D008207:Lymphatic Metastasis; D015412:Mastectomy, Segmental; D012307:Risk Factors; D016019:Survival Analysis