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. 2020 Sep 28:12:9173-9182.
doi: 10.2147/CMAR.S269893. eCollection 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

Chia-Hsin Chen  1 , Ching-Chuan Hsieh  2 , Chih-Shen Chang  1 , Miao-Fen Chen  1   3
Affiliations

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

Chia-Hsin Chen et al. Cancer Manag Res. .

Abstract

Background: 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: 3D-CRT; IMRT; OAR; breast cancer; toxicity.

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Conflict of interest statement

The authors declare that they have no competing interests for this work.

Figures

Figure 1
Figure 1
Radiation hotspots related to acute skin toxicity. (A) Representative pictures of selected patients with grade 1 and 2 acute skin toxicity, and the isodose distribution are shown, respectively (% of prescribed dose: color curve; 95%: yellow curve; 105%: pink curve; 107%: light blue). (B) The volume of radiation hotspots in the groups of patients without and with radiation dermatitis.
Figure 2
Figure 2
Relationship between MHD and the distance of heart (DHL) for left-sided breast cancer patients. (A) Representative images of the distance of heart (DHL) is shown (A: the midline of the sternum; B: the left middle axillary line; DHL: orange; PTV: light green). (B) The values of DHL plotted against mean heart dose. DHL indicated good positive linear correlation with mean heart dose for all patients.
Figure 3
Figure 3
Relationship between RT-induced radiologic changes and V20 of ipsilateral lung Representative pictures of a selected patient with RT-induced radiologic changes and the isodose distribution are shown, respectively (prescribed dose: yellow curve; V20: orange curve).
See this image and copyright information in PMC

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