Second cancer risk after 3D-CRT, IMRT and VMAT for breast cancer

Radiother Oncol. 2014 Mar;110(3):471-6. doi: 10.1016/j.radonc.2013.12.002. Epub 2014 Jan 17.

Abstract

Purpose: Second cancer risk after breast conserving therapy is becoming more important due to improved long term survival rates. In this study, we estimate the risks for developing a solid second cancer after radiotherapy of breast cancer using the concept of organ equivalent dose (OED).

Materials and methods: Computer-tomography scans of 10 representative breast cancer patients were selected for this study. Three-dimensional conformal radiotherapy (3D-CRT), tangential intensity modulated radiotherapy (t-IMRT), multibeam intensity modulated radiotherapy (m-IMRT), and volumetric modulated arc therapy (VMAT) were planned to deliver a total dose of 50 Gy in 2 Gy fractions. Differential dose volume histograms (dDVHs) were created and the OEDs calculated. Second cancer risks of ipsilateral, contralateral lung and contralateral breast cancer were estimated using linear, linear-exponential and plateau models for second cancer risk.

Results: Compared to 3D-CRT, cumulative excess absolute risks (EAR) for t-IMRT, m-IMRT and VMAT were increased by 2 ± 15%, 131 ± 85%, 123 ± 66% for the linear-exponential risk model, 9 ± 22%, 82 ± 96%, 71 ± 82% for the linear and 3 ± 14%, 123 ± 78%, 113 ± 61% for the plateau model, respectively.

Conclusion: Second cancer risk after 3D-CRT or t-IMRT is lower than for m-IMRT or VMAT by about 34% for the linear model and 50% for the linear-exponential and plateau models, respectively.

Keywords: Breast cancer; Intensity modulated radiation therapy (IMRT); Organ equivalent dose (OED); Second cancer risk.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Breast Neoplasms / radiotherapy*
  • Female
  • Humans
  • Middle Aged
  • Neoplasms, Radiation-Induced*
  • Neoplasms, Second Primary / etiology*
  • Radiotherapy Dosage
  • Radiotherapy Planning, Computer-Assisted / methods
  • Radiotherapy, Conformal / adverse effects*
  • Radiotherapy, Intensity-Modulated / adverse effects*
  • Risk