title: Is there an increased risk of local recurrence under the heart block in patients with left-sided breast cancer?
abstract: Tangential radiotherapy for left-sided breast cancer may be cardiotoxic. Shaping the field with a heart block reduces cardiac exposure but may under-dose the breast and/or chest wall. We compared the incidence and location of local recurrences in patients irradiated with and without a heart block.
  
  
  METHODS
  Between 1994 and 1998, 180 patients irradiated to the left breast and/or chest wall were retrospectively reviewed. The local recurrence rates in patients treated with and without a heart block were compared using a 2-tailed Fisher exact test. An in-depth dosimetric analysis was performed in 23 patients to assess the percentage of breast tissue under-dosed by inclusion of the heart block.
  
  
  RESULTS
  Overall, the local recurrence rates in patients with or without a heart block were similar. In postlumpectomy patients with inferiorly located tumors, the rates of local recurrence with and without a heart block were 2 of 6 patients versus 0 of 19 patients, respectively. In the dosimetric analysis, the average percentage of breast tissue under-dosed by the inclusion of a heart block was 2.8% (range, 0%-11%).
  
  
  CONCLUSIONS
  A heart block is a reasonable method to limit cardiac dose but should be used cautiously following a lumpectomy in patients with inferiorly located tumors. Additional study with larger numbers of patients is warranted.
authors.affiliation: Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Katelyn A
authors.initials: KA
authors.lastname: Raj
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Evans
authors.forename: Robert G
authors.initials: RG
authors.lastname: Prosnitz
authors.forename: Brian P
authors.initials: BP
authors.lastname: Quaranta
authors.forename: Patricia H
authors.initials: PH
authors.lastname: Hardenbergh
authors.forename: Donna R
authors.initials: DR
authors.lastname: Hollis
authors.forename: Kim L
authors.initials: KL
authors.lastname: Light
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Marks
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology / Q000503:physiopathology* / Q000532:radiotherapy* / Q000601:surgery; D018270:Carcinoma, Ductal, Breast / Q000473:pathology / Q000503:physiopathology* / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006327:Heart Block / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000503:physiopathology; D011878:Radiotherapy / Q000379:methods*; D011879:Radiotherapy Dosage