title: Risk estimation of second primary cancers after breast radiotherapy.
abstract: OBJECTIVE
  There is evidence towards the induction of second primary cancers (SPCs) after breast radiotherapy (RT). Organs, such as the lungs and the esophagus, have been identified as common sites for SPC formation. As a result, the current study investigated the risk of secondary carcinogenesis associated with particular RT techniques for breast cancer; including whole breast, segmented breast, partial breast and mammosite brachytherapy.
  
  
  METHODS
  In this study, seven breast cancer patients had all major organs contoured on their planning computed tomography (CT) images. Whole breast, segmented breast, accelerated partial breast irradiation (APBI) and mammosite boost treatment plans were generated for each patient using Pinnacle3 treatment planning system. Differential dose-volume histograms were generated for a number of critical structures: bladder, brain and central nervous system (CNS), breast, colon, liver, lung, mouth and pharynx, esophagus, ovary, salivary gland, small intestine, stomach, and uterus. The lifetime attributed risk (LAR) of cancer induction was estimated using the Schneider et al. excess absolute risk models and dose-volume histograms for the above organs.
  
  
  RESULTS
  The sites with the highest LAR estimates were the ipsilateral and contralateral lungs, and contralateral breast for all treatment techniques. For all sites, the LAR estimates for the segmented breast and mammosite treatments were lower than those for the whole breast and APBI treatments. For right-sided target volumes the liver also resulted in high LAR estimates, with all techniques having a LAR greater than 20 per 10 000 person-years (PY), except for mammosite with a mean LAR estimate of 13.2 per 10 000 PY. For left-sided target volumes the stomach also resulted in high LAR estimates, with both whole breast and APBI having a LAR greater than 20 per 10 000 PY, and mammosite the lowest with a LAR of 8.3 per 10 000 PY.
  
  
  CONCLUSIONS
  It is concluded that the lungs and contralateral breast showed high LAR estimates.
authors.affiliation: a School of Physical Sciences, University of Adelaide , Adelaide , South Australia , Australia.|b Department of Medical Physics , Royal Adelaide Hospital , Adelaide , South Australia , Australia.
authors.forename: Alexandre M C
authors.initials: AM
authors.lastname: Santos
authors.affiliation: a School of Physical Sciences, University of Adelaide , Adelaide , South Australia , Australia.|c Faculty of Science , University of Oradea , Oradea , Romania.
authors.forename: Loredana G
authors.initials: LG
authors.lastname: Marcu
authors.affiliation: d Department of Radiation Oncology , Royal Adelaide Hospital , Adelaide , South Australia , Australia.
authors.forename: Chia M
authors.initials: CM
authors.lastname: Wong
authors.affiliation: a School of Physical Sciences, University of Adelaide , Adelaide , South Australia , Australia.|e International Centre for Allied Health Evidence and Sansom Institute for Health Research, Division of Health Sciences, University of South Australia , Adelaide , South Australia , Australia.
authors.forename: Eva
authors.initials: E
authors.lastname: Bezak
mesh_terms: D000368:Aged; D001918:Brachytherapy / Q000009:adverse effects* / Q000379:methods; D001943:Breast Neoplasms / Q000532:radiotherapy*; D004947:Esophagus / Q000528:radiation effects; D005260:Female; D006801:Humans; D008099:Liver / Q000528:radiation effects; D008168:Lung / Q000528:radiation effects; D008175:Lung Neoplasms / Q000209:etiology; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000209:etiology*; D058958:Organs at Risk / Q000528:radiation effects; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012307:Risk Factors; D013270:Stomach / Q000528:radiation effects