External beam boost versus interstitial high-dose-rate brachytherapy boost in the adjuvant radiotherapy following breast-conserving therapy in early-stage breast cancer: a dosimetric comparison

• Main Authors: Martje Marie Terheyden, Corinna Melchert, György Kovács
• Format: Article
• Language: English
• Published: Termedia Publishing House 2016-08-01
• Series: Journal of Contemporary Brachytherapy
• Subjects: adjuvant radiotherapy; breast cancer; dosimetry; EBRT; HDR brachytherapy (HDR-BT)
• Online Access: https://www.termedia.pl/External-beam-boost-versus-interstitial-high-dose-rate-brachytherapy-boost-in-the-adjuvant-radiotherapy-following-breast-conserving-therapy-in-early-stage-breast-cancer-a-dosimetric-comparison,54,28242,1,1.html
• ISSN: 1689-832X; 2081-2841

Purpose : This study aims to compare the dosimetric data of local tumor’s bed dose escalation (boost) with photon beams (external beam radiation therapy – EBRT) versus high-dose-rate interstitial brachytherapy (HDR-BT) after breast-conserving treatment in women with early-stage breast cancer. Material and methods : We analyzed the treatment planning data of 136 irradiated patients, treated between 2006 and 2013, who underwent breast-conserving surgery and adjuvant whole breast irradiation (WBI; 50.4 Gy) and boost (HDR-BT: 10 Gy in one fraction [n = 36]; EBRT: 10 Gy in five fractions [n = 100]). Organs at risk (OAR; heart, ipsilateral lung, skin, most exposed rib segment) were delineated. Dosimetric parameters were calculated with the aid of dose-volume histograms (DVH). A non-parametric test was performed to compare the two different boost forms. Results : There was no difference for left-sided cancers regarding the maximum dose to the heart (HDR-BT 29.8% vs. EBRT 29.95%, p = 0.34). The maximum doses to the other OAR were significantly lower for HDR-BT (Dmax lung 47.12% vs. 87.7%, p < 0.01; rib 61.17% vs. 98.5%, p < 0.01; skin 57.1% vs. 94.75%, p < 0.01; in the case of right-sided breast irradiation, dose of the heart 6.00% vs. 16.75%, p < 0.01). Conclusions : Compared to EBRT, local dose escalation with HDR-BT presented a significant dose reduction to the investigated OAR. Only left-sided irradiation showed no difference regarding the maximum dose to the heart. Reducing irradiation exposure to OAR could result in a reduction of long-term side effects. Therefore, from a dosimetric point of view, an interstitial boost complementary to WBI via EBRT seems to be more advantageous in the adjuvant radiotherapy of breast cancer.