title: Left-Sided Breast Irradiation does not Result in Increased Long-Term Cardiac-Related Mortality Among Women Treated with Breast-Conserving Surgery.
abstract: BACKGROUND
  Standard therapy following lumpectomy for breast cancer has included adjuvant whole-breast radiotherapy. Recent, long-term studies have suggested a possible association between left-sided whole breast radiotherapy and long-term cardiac-related mortality. We sought to determine whether left-sided breast cancers treated with breast-conserving treatment have worse cardiac-related outcomes.
  
  
  METHODS
  The surveillance, epidemiology, and end results database was queried for female breast cancer cases diagnosed from 1990 to 1999. Subjects who underwent lumpectomy and adjuvant radiotherapy were included for study and grouped according to laterality. The primary outcome measure was the rate of cardiac-related mortality. Secondary outcome measures were overall and cancer-specific survival. A Cox proportional hazards model was constructed to analyze the primary outcome measure and included age, race, grade, stage, hormone receptor status, and histologic subtype.
  
  
  RESULTS
  A total of 66,687 subjects were identified. These were divided equally by laterality groups: 33,866 left (50.8 %) and 32,801 right (49.2 %). Median follow-up was 15.5 years, and the groups were otherwise well-matched. Left-sided cancer was not associated with poorer survival for any of the metrics. Fifteen-year overall survival and disease-specific survival were 62.8 and 87.0 % for left-sided and 63.0 and 87.1 % for right-sided breast cancers, respectively (p = 0.260, p = 0.702). Rate of cardiac-related mortality at 5-, 10-, and 15-year follow-up were 1.5, 4.3, and 7.7 % for left-sided cancers and 1.6, 4.4, and 8.0 % for right-sided cancers, respectively (p = 0.435).
  
  
  CONCLUSIONS
  In this large population-based study, women receiving left-sided external beam radiation for breast cancer did not have an increase in cardiac-related mortality.
authors.affiliation: Grand Rapids Medical Education Partners/Michigan State University General Surgery Residency Program, Grand Rapids, MI, USA. wrightgp@upmc.edu.|Department of Surgery, Michigan State University College of Human Medicine, Grand Rapids, MI, USA. wrightgp@upmc.edu.|Division of Surgical Specialties, Spectrum Health Medical Group, Grand Rapids, MI, USA. wrightgp@upmc.edu.|Division of Surgical Oncology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA. wrightgp@upmc.edu.
authors.forename: G
authors.initials: G
authors.lastname: Paul Wright
authors.affiliation: Grand Rapids Medical Education Partners/Michigan State University General Surgery Residency Program, Grand Rapids, MI, USA.
authors.forename: James J
authors.initials: JJ
authors.lastname: Drinane
authors.affiliation: Department of Surgery, Michigan State University College of Human Medicine, Grand Rapids, MI, USA.
authors.forename: Holly L
authors.initials: HL
authors.lastname: Sobel
authors.affiliation: Grand Rapids Medical Education Partners/Michigan State University General Surgery Residency Program, Grand Rapids, MI, USA.|Department of Surgery, Michigan State University College of Human Medicine, Grand Rapids, MI, USA.|Division of Surgical Specialties, Spectrum Health Medical Group, Grand Rapids, MI, USA.
authors.forename: Mathew H
authors.initials: MH
authors.lastname: Chung
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D018270:Carcinoma, Ductal, Breast / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D018275:Carcinoma, Lobular / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006321:Heart / Q000528:radiation effects*; D006801:Humans; D015412:Mastectomy, Segmental; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011379:Prognosis; D011832:Radiation Injuries / Q000401:mortality*; D012189:Retrospective Studies; D018426:SEER Program; D015996:Survival Rate