Potential skin morbidity reduction with intensity-modulated proton therapy for breast cancer with nodal involvement


Background: Different modern radiation therapy treatment solutions for breast cancer (BC) and regional nodal irradiation (RNI) have been proposed. In this study, we evaluate the potential reduction in radiation-induced skin morbidity obtained by intensity modulated proton therapy (IMPT) compared with intensity modulated photon therapy (IMXT) for left-side BC and RNI.

Material and Methods: Using CT scans from 10 left-side BC patients, treatment plans were generated using IMXT and IMPT techniques. A dose of 50 Gy (or Gy [RBE] for IMPT) was prescribed to the target volume (involved breast, the internal mammary, supraclavicular, and infraclavicular nodes). Two single filed optimization IMPT (IMPT1 and IMPT2) plans were calculated without and with skin optimization. For each technique, skin dose-metrics were extracted and normal tissue complication probability (NTCP) models from the literature were employed to estimate the risk of radiation-induced skin morbidity. NTCPs for relevant organs-at-risk (OARs) were also considered for reference. The non-parametric Anova (Friedman matched-pairs signed-rank test) was used for comparative analyses.

Results: IMPT improved target coverage and dose homogeneity even if the skin was included into optimization strategy (HIIMPT2 = 0.11 vs. HIIMXT = 0.22 and CIIMPT2 = 0.96 vs. CIIMXT = 0.82, p < .05). A significant relative skin risk reduction (RR = NTCPIMPT/NTCPIMXT) was obtained with IMPT2 including the skin in the optimization with a RR reduction ranging from 0.3 to 0.9 depending on the analyzed skin toxicity endpoint/model. Both IMPT plans attained significant OARs dose sparing compared with IMXT. As expected, the heart and lung doses were significantly reduced using IMPT. Accordingly, IMPT always provided lower NTCP values.

Conclusions: IMPT guarantees optimal target coverage, OARs sparing, and simultaneously minimizes the risk of skin morbidity. The applied model-based approach supports the potential clinical relevance of IMPT for left-side BC and RNI and might be relevant for the setup of cost-effectiveness evaluation strategies based on NTCP predictions, as well as for establishing patient selection criteria.

Francesco Fellin, Martina Iacco, Vittoria D’Avino, Francesco Tommasino, Paolo Farace, Giuseppe Palma, Manuel Conson, Irene Giacomelli, Claudio Zucchetti, Lorenzo Falcinelli, Maurizio Amichetti, Cynthia Aristei & Laura Cella(2019) Potential skin morbidity reduction with intensity-modulated proton therapy for breast cancer with nodal involvement, Acta Oncologica, DOI: 10.1080/0284186X.2019.1591638

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Cardiotoxicity Associated with Radiation for Breast Cancer

Leonard K.L., Wazer D.E. (2019). In: Wright J. (eds) Toxicities of Radiation Treatment for Breast Cancer. Springer, Cham

“Strategies to reduce cardiac dose, including deep inspiration breath hold, prone positioning, partial breast irradiation, and proton therapy should be considered, particularly in women at high risk for cardiotoxicity. Based on available data, most current protocols recommend limiting mean cardiac dose and the dose to 5% and 10% of the cardiac volume.”


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The relationship between radiation doses to coronary arteries and location of coronary stenosis requiring intervention in breast cancer survivors

Anna-Karin Wennstig, Hans Garmo, Ulf Isacsson, Giovanna Gagliardi, Niina Rintelä, Bo Lagerqvist, Lars Holmberg, Carl Blomqvist, Malin Sund and Greger Nilsson

Radiation Oncology201914:40

This study assessed the relationship between radiation doses to the coronary arteries (CAs) and location of a coronary stenosis that required intervention after three-dimensional conformal radiotherapy (3DCRT) for breast cancer (BC).

In women receiving conventional 3D Conformal RadioTherapy for Breast Cancer between 1992 and 2012, radiation doses to the Left Anterior Descending Artery (LAD) remained high and were associated with an increased requirement of coronary intervention in mid LAD. The results support that the LAD radiation dose should be considered in RT treatment planning and that the dose should be kept as low as possible.

Reducing the dose to LAD, and implementation of heart-sparing RT techniques is of importance, since minimising the dose to LAD is expected to diminish the risk of later radiation-induced stenosis.


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