Cancer Management and Research (Sep 2020)

A Retrospective Analysis of Dose Distribution and Toxicity in Patients with Left Breast Cancer Treated with Adjuvant Intensity-Modulated Radiotherapy: Comparison with Three-Dimensional Conformal Radiotherapy

  • Chen CH,
  • Hsieh CC,
  • Chang CS,
  • Chen MF

Journal volume & issue
Vol. Volume 12
pp. 9173 – 9182

Abstract

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Chia-Hsin Chen,1 Ching-Chuan Hsieh,2 Chih-Shen Chang,1 Miao-Fen Chen1,3 1Department of Radiation Oncology, Chang Gung Memorial Hospital, Chiayi, Taiwan; 2Department of General Surgery, Chang Gung Memorial Hospital, Chiayi, Taiwan; 3Chang Gung University College of Medicine, Taoyuan City, TaiwanCorrespondence: Miao-Fen ChenDepartment of Radiation Oncology, Chang Gung Memorial Hospital at Chiayi, Chiayi, TaiwanEmail [email protected]: A better understanding of the organs-at-risk (OAR) dose metrics and the related toxicity induced by radiotherapy (RT) for left breast cancer (BC) will improve the quality of life. This study addressed the issue for left-BC patients treated with intensity-modulated radiotherapy (IMRT) compared to three-dimensional conformal radiotherapy (3D-CRT).Patients and Methods: Between 2012 and 2018, 308 left-BC patients underwent adjuvant RT at our hospital. Before June 2015, 134 patients were treated with 3D-CRT. Thereafter, 174 patients underwent IMRT. The patient’s characteristics in the IMRT group did not significantly different compared to those in the 3D-CRT group.Results: Among the total study population, the incidence of ≥grade 2 radiation dermatitis (RID) was 17.3%. Higher volumes receiving 105% (≥ 5.7%) and 107% (≥ 1%) of prescribed dose and 3D-CRT technique were associated with a higher risk of RID. Regarding lung toxicity, the mean lung dose (≥ 10.2Gy) and V20 (≥ 20%) of ipsilateral lung were significantly associated with the incidence of RT-induced pulmonary changes. By dosimetry analysis, IMRT achieved better dose conformity and delivered lower mean doses to heart and ipsilateral lung compared to 3D-CRT. Furthermore, propensity sore and multivariate analysis showed that IMRT technique helped to reduce RT-induced dermatitis and lung toxicity.Conclusion: Our data suggest that the volume of OAR exposed to higher doses is a predictor of RT-induced toxicity. Adjuvant RT with IMRT technique offered better dose conformity and spared high-dose levels to OARs to reduce radiation-related morbidity for BC patients.Keywords: breast cancer, IMRT, 3D-CRT, OAR, toxicity

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