title: Does breast composition influence late adverse effects in breast radiotherapy?
abstract: BACKGROUND
  Large breast size is associated with increased risk of late adverse effects after surgery and radiotherapy for early breast cancer. It is hypothesised that effects of radiotherapy on adipose tissue are responsible for some of the effects seen. In this study, the association of breast composition with late effects was investigated along with other breast features such as fibroglandular tissue distribution, seroma and scar.
  
  
  METHODS
  The patient dataset comprised of 18 cases with changes in breast appearance at 2 years follow-up post-radiotherapy and 36 controls with no changes, from patients entered into the FAST-Pilot and UK FAST trials at The Royal Marsden. Breast composition, fibroglandular tissue distribution, seroma and scar were assessed on planning CT scan images and compared using univariate analysis. The association of all features with late-adverse effect was tested using logistic regression (adjusting for confounding factors) and matched analysis was performed using conditional logistic regression.
  
  
  RESULTS
  In univariate analyses, no statistically significant differences were found between cases and controls in terms of breast features studied. A statistically significant association (p < 0.05) between amount of seroma and change in photographic breast appearance was found in unmatched and matched logistic regression analyses with odds ratio (95% CI) of 3.44 (1.28-9.21) and 2.57 (1.05-6.25), respectively.
  
  
  CONCLUSIONS
  A significant association was found between seroma and late-adverse effects after radiotherapy although no significant associations were noted with breast composition in this study. Therefore, the cause for large breast size as a risk factor for late effects after surgery and optimally planned radiotherapy remains unresolved.
authors.affiliation: The Institute of Cancer Research, London SW7 3RP, UK; The Royal Marsden NHS Foundation Trust, Sutton SM2 5PT, UK; North Sydney Cancer Centre, Royal North Shore Hospital, Sydney 2065, Australia; Institute of Medical Physics, University of Sydney, Sydney 2006, Australia.
authors.forename: Prabhjot
authors.initials: P
authors.lastname: Juneja
authors.affiliation: Centro Nazionale Adroterapia Oncologica, 27100 Pavia, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Bonora
authors.affiliation: Faculty of Health Sciences, University of Southampton, Southampton SO17 1BJ, UK; ICR-Clinical Trials and Statistics Unit (ICR-CTSU), Division of Clinical Studies, The Institute of Cancer Research, London SM2 5NG, UK.
authors.forename: Joanne S
authors.initials: JS
authors.lastname: Haviland
authors.affiliation: The Institute of Cancer Research, London SW7 3RP, UK; The Royal Marsden NHS Foundation Trust, Sutton SM2 5PT, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Harris
authors.affiliation: The Institute of Cancer Research, London SW7 3RP, UK; The Royal Marsden NHS Foundation Trust, Sutton SM2 5PT, UK; Centre for Vision Speech and Signal Processing, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, UK.
authors.forename: Phil
authors.initials: P
authors.lastname: Evans
authors.affiliation: The Institute of Cancer Research, London SW7 3RP, UK; The Royal Marsden NHS Foundation Trust, Sutton SM2 5PT, UK. Electronic address: navita.somaiah@icr.ac.uk.
authors.forename: Navita
authors.initials: N
authors.lastname: Somaiah
mesh_terms: D000368:Aged; D001940:Breast / Q000000981:diagnostic imaging / Q000473:pathology* / Q000528:radiation effects; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D000069451:Long Term Adverse Effects / Q000209:etiology*; D008875:Middle Aged; D009929:Organ Size / Q000528:radiation effects; D011878:Radiotherapy / Q000009:adverse effects; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D012307:Risk Factors; D049291:Seroma / Q000000981:diagnostic imaging / Q000532:radiotherapy; D014057:Tomography, X-Ray Computed
keywords: Breast radiotherapy; Breast segmentation; Seroma; Toxicity