title: Radiation dose to the esophagus from breast cancer radiation therapy, 1943-1996: an international population-based study of 414 patients.
abstract: OBJECTIVE
  To provide dosimetric data for an epidemiologic study on the risk of second primary esophageal cancer among breast cancer survivors, by reconstructing the radiation dose incidentally delivered to the esophagus of 414 women treated with radiation therapy for breast cancer during 1943-1996 in North America and Europe.
  
  
  METHODS
  We abstracted the radiation therapy treatment parameters from each patient's radiation therapy record. Treatment fields included direct chest wall (37% of patients), medial and lateral tangentials (45%), supraclavicular (SCV, 64%), internal mammary (IM, 44%), SCV and IM together (16%), axillary (52%), and breast/chest wall boosts (7%). The beam types used were (60)Co (45% of fields), orthovoltage (33%), megavoltage photons (11%), and electrons (10%). The population median prescribed dose to the target volume ranged from 21 Gy to 40 Gy. We reconstructed the doses over the length of the esophagus using abstracted patient data, water phantom measurements, and a computational model of the human body.
  
  
  RESULTS
  Fields that treated the SCV and/or IM lymph nodes were used for 85% of the patients and delivered the highest doses within 3 regions of the esophagus: cervical (population median 38 Gy), upper thoracic (32 Gy), and middle thoracic (25 Gy). Other fields (direct chest wall, tangential, and axillary) contributed substantially lower doses (approximately 2 Gy). The cervical to middle thoracic esophagus received the highest dose because of its close proximity to the SCV and IM fields and less overlying tissue in that part of the chest. The location of the SCV field border relative to the midline was one of the most important determinants of the dose to the esophagus.
  
  
  CONCLUSIONS
  Breast cancer patients in this study received relatively high incidental radiation therapy doses to the esophagus when the SCV and/or IM lymph nodes were treated, whereas direct chest wall, tangentials, and axillary fields contributed lower doses.
authors.affiliation: Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA. stephanie.lamart@nih.gov
authors.forename: Stephanie
authors.initials: S
authors.lastname: Lamart
authors.forename: Marilyn
authors.initials: M
authors.lastname: Stovall
authors.forename: Steven L
authors.initials: SL
authors.lastname: Simon
authors.forename: Susan A
authors.initials: SA
authors.lastname: Smith
authors.forename: Rita E
authors.initials: RE
authors.lastname: Weathers
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Howell
authors.forename: Rochelle E
authors.initials: RE
authors.lastname: Curtis
authors.forename: Berthe M P
authors.initials: BM
authors.lastname: Aleman
authors.forename: Lois
authors.initials: L
authors.lastname: Travis
authors.forename: Deukwoo
authors.initials: D
authors.lastname: Kwon
authors.forename: Lindsay M
authors.initials: LM
authors.lastname: Morton
mesh_terms: D001943:Breast Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D004307:Dose-Response Relationship, Radiation; D004938:Esophageal Neoplasms; D004947:Esophagus / Q000528:radiation effects*; D005060:Europe; D005260:Female; D006801:Humans; D015182:Lymphatic Irradiation / Q000706:statistics & numerical data; D008408:Mastectomy / Q000706:statistics & numerical data; D015412:Mastectomy, Segmental / Q000706:statistics & numerical data; D009381:Neoplasms, Radiation-Induced; D016609:Neoplasms, Second Primary; D009656:North America; D058958:Organs at Risk / Q000528:radiation effects*; D019047:Phantoms, Imaging; D011879:Radiotherapy Dosage; D018570:Risk Assessment; D035441:Thoracic Wall / Q000528:radiation effects; D035501:Uncertainty