title: Cardiac morbidity of adjuvant radiotherapy for breast cancer.
abstract: OBJECTIVE
  Adjuvant breast irradiation has been associated with an increase in cardiac mortality, because left-sided breast radiation can produce cardiac damage. The purpose of this study was to determine whether modern adjuvant radiotherapy is associated with increased risk of cardiac morbidity.
  
  
  METHODS
  Data from the Surveillance, Epidemiology, and End Results-Medicare database were used for women who were diagnosed with nonmetastatic breast cancer from 1986 to 1993, had known disease laterality, underwent breast surgery, and received adjuvant radiotherapy. The Cox proportional-hazards model was used to compare patients with left- versus right-sided breast cancer for the end points of hospitalization with the following discharge diagnoses (International Classification of Diseases, 9th Revision codes): ischemic heart disease (410-414, 36.0, and 36.1), valvular heart disease (394-397, 424, 35), congestive heart failure (428, 402.01, 402.11, 402.91, and 425), and conduction abnormalities (426, 427, 37.7-37.8, and 37.94-37.99).
  
  
  RESULTS
  Eight thousand three hundred sixty-three patients had left-sided breast cancer, and 7,907 had right-sided breast cancer. Mean follow-up was 9.5 years (range, 0 to 15 years). There were no significant differences in patients with left- versus right-sided cancers for hospitalization for ischemic heart disease (9.9% v 9.7%), valvular heart disease (2.9% v 2.8%), conduction abnormalities (9.7% v 9.6%), or heart failure (9.7% v 9.7%). The adjusted hazard ratio for left- versus right-sided breast cancer was 1.05 (95% CI, 0.94 to 1.16) for ischemic heart disease, 1.07 (95% CI, 0.89 to 1.30) for valvular heart disease, 1.07 (95% CI, 0.96 to 1.19) for conduction abnormalities, and 1.05 (95% CI, 0.95 to 1.17) for heart failure.
  
  
  CONCLUSIONS
  With up to 15 years of follow-up there were no significant differences in cardiac morbidity after radiation for left- versus right-sided breast cancer.
authors.affiliation: Department of Medical Oncology, Houston, TX 77030, USA.
authors.forename: Debra A
authors.initials: DA
authors.lastname: Patt
authors.forename: James S
authors.initials: JS
authors.lastname: Goodwin
authors.forename: Yong-Fang
authors.initials: YF
authors.lastname: Kuo
authors.forename: Jean L
authors.initials: JL
authors.lastname: Freeman
authors.forename: Dong D
authors.initials: DD
authors.lastname: Zhang
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Buchholz
authors.forename: Gabriel N
authors.initials: GN
authors.lastname: Hortobagyi
authors.forename: Sharon H
authors.initials: SH
authors.lastname: Giordano
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000532:radiotherapy*; D005260:Female; D006321:Heart / Q000528:radiation effects*; D006331:Heart Diseases / Q000209:etiology*; D006801:Humans; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects*; D018426:SEER Program; D015996:Survival Rate; D013997:Time Factors; D014481:United States / Q000453:epidemiology