title: Adjuvant hypofractionated versus conventional whole breast radiation therapy for early-stage breast cancer: long-term hospital-related morbidity from cardiac causes.
abstract: OBJECTIVE
  The risk of cardiac injury with hypofractionated whole-breast/chest wall radiation therapy (HF-WBI) compared with conventional whole-breast/chest wall radiation therapy (CF-WBI) in women with left-sided breast cancer remains a concern. The purpose of this study was to determine if there is an increase in hospital-related morbidity from cardiac causes with HF-WBI relative to CF-WBI.
  
  
  METHODS
  Between 1990 and 1998, 5334 women ≤ 80 years of age with early-stage breast cancer were treated with postoperative radiation therapy to the breast or chest wall alone. A population-based database recorded baseline patient, tumor, and treatment factors. Hospital administrative records identified baseline cardiac risk factors and other comorbidities. Factors between radiation therapy groups were balanced using a propensity-score model. The first event of a hospital admission for cardiac causes after radiation therapy was determined from hospitalization records. Ten- and 15-year cumulative hospital-related cardiac morbidity after radiation therapy was estimated for left- and right-sided cases using a competing risk approach.
  
  
  RESULTS
  The median follow-up was 13.2 years. For left-sided cases, 485 women were treated with CF-WBI, and 2221 women were treated with HF-WBI. Mastectomy was more common in the HF-WBI group, whereas boost was more common in the CF-WBI group. The CF-WBI group had a higher prevalence of diabetes. The 15-year cumulative hospital-related morbidity from cardiac causes (95% confidence interval) was not different between the 2 radiation therapy regimens after propensity-score adjustment: 21% (19-22) with HF-WBI and 21% (17-25) with CF-WBI (P=.93). For right-sided cases, the 15-year cumulative hospital-related morbidity from cardiac causes was also similar between the radiation therapy groups (P=.76).
  
  
  CONCLUSIONS
  There is no difference in morbidity leading to hospitalization from cardiac causes among women with left-sided early-stage breast cancer treated with HF-WBI or CF-WBI at 15-year follow-up.
authors.affiliation: Department of Oncology, Saint John Regional Hospital, Saint John, Canada.
authors.forename: Elisa K
authors.initials: EK
authors.lastname: Chan
authors.affiliation: Cancer Control Research Department, BC Cancer Agency, Vancouver, Canada.
authors.forename: Ryan
authors.initials: R
authors.lastname: Woods
authors.affiliation: Cancer Control Research Department, BC Cancer Agency, Vancouver, Canada.
authors.forename: Mary L
authors.initials: ML
authors.lastname: McBride
authors.affiliation: Division of Cardiology, University of British Columbia, Vancouver, Canada.
authors.forename: Sean
authors.initials: S
authors.lastname: Virani
authors.affiliation: Radiation Therapy Program, BC Cancer Agency, Vancouver, Canada.
authors.forename: Alan
authors.initials: A
authors.lastname: Nichol
authors.affiliation: Breast Cancer Outcomes Unit, BC Cancer Agency, Vancouver, Canada.
authors.forename: Caroline
authors.initials: C
authors.lastname: Speers
authors.affiliation: Radiation Therapy Program, BC Cancer Agency, Vancouver, Canada.
authors.forename: Elaine S
authors.initials: ES
authors.lastname: Wai
authors.affiliation: Radiation Therapy Program, BC Cancer Agency, Vancouver, Canada. Electronic address: styldesl@bccancer.bc.ca.
authors.forename: Scott
authors.initials: S
authors.lastname: Tyldesley
mesh_terms: D000368:Aged; D001940:Breast / Q000473:pathology; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D001955:British Columbia; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D006321:Heart / Q000528:radiation effects*; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008408:Mastectomy / Q000706:statistics & numerical data; D008875:Middle Aged; D009367:Neoplasm Staging; D009929:Organ Size; D058958:Organs at Risk / Q000528:radiation effects*; D011832:Radiation Injuries / Q000150:complications*; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects; D012307:Risk Factors; D035441:Thoracic Wall