title: Estimated Risk of Radiation Induced Contra Lateral Breast Cancer Following Chest Wall Irradiation by Conformal Wedge Field and Forward Intensity Modulated Radiotherapy Technique for Post-Mastectomy Breast Cancer Patients
abstract: Background: Epidemiological studies have indicated an increasing incidence of radiation induced secondary
  cancer (SC) in breast cancer patients after radiotherapy (RT), most commonly in the contra-lateral breast (CLB). The
  present study was conducted to estimate the SC risk in the CLB following 3D conformal radiotherapy techniques
  (3DCRT) including wedge field and forward intensity modulated radiotherapy (fIMRT) based on the organ equivalent
  dose (OED). Material and Methods: RT plans treating the chest wall with conformal wedge field and fIMRT plans
  were created for 30 breast cancer patients. The risks of radiation induced cancer were estimated for the CLB using
  dose-response models: a linear model, a linear-plateau model and a bell-shaped model with full dose response accounting
  for fractionated RT on the basis of OED. Results: The plans were found to be ranked quite differently according to
  the choice of model; calculations based on a linear dose response model fIMRT predict statistically significant lower
  risk compared to the enhanced dynamic wedge (EDW) technique (p-0.0089) and a non-significant difference between
  fIMRT and physical wedge (PW) techniques (p-0.054). The widely used plateau dose response model based estimation
  showed significantly lower SC risk associated with fIMRT technique compared to both wedge field techniques (fIMRT
  vs EDW p-0.013, fIMRT vs PW p-0.04). The full dose response model showed a non-significant difference between
  all three techniques in the view of second CLB cancer. Finally the bell shaped model predicted interestingly that PW
  is associated with significantly higher risk compared to both fIMRT and EDW techniques (fIMRT vs PW p-0.0003,
  EDW vs PW p-0.0032). Conclusion: In conclusion, the SC risk estimations of the CLB revealed that there is a clear
  relation between risk associated with wedge field and fIMRT technique depending on the choice of model selected for
  risk comparison.
authors.affiliation: Department of Radiological Physics, SP Medical College, Bikaner, India. Email: mailtohemathi@gmail.com
authors.forename: Hemalatha
authors.initials: H
authors.lastname: Athiyaman
authors.forename: Athiyaman
authors.initials: A
authors.lastname: m
authors.forename: Arun
authors.initials: A
authors.lastname: Chougule
authors.forename: Kumar
authors.initials: K
authors.lastname: Hs
keywords: Organ Equivalent Dose; contra lateral breast; second Cancer Risk