Low doses to the heart in daily practice for treating left-sided breast cancer using accelerated partial-breast irradiation by multicatheter brachytherapy and deep-inspiration breath-hold using a SIB

• Published in: Strahlentherapie und Onkologie 2023-04, Vol.199 (4), p.389-395
• Main Authors: Knippen, Stefan, Schönherr, Sven, Schwedas, Michael, Teichmann, Tobias, Howitz, Simon, Mäurer, Matthias, Wittig-Sauerwein, Andrea, Duma, Marciana-Nona
• Format: Article
• Language: English
• Subjects: Biological effects; Brachytherapy - methods; Breast cancer; Breast Neoplasms - radiotherapy; Breath Holding; Dosimetry; Female; Heart; Heart - radiation effects; Humans; Inspiration; Mathematical analysis; Medicine; Medicine & Public Health; Oncology; Organs at Risk - radiation effects; Original; Original Article; Radiation dosage; Radiation therapy; Radiotherapy; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted - methods; Tumors; Unilateral Breast Neoplasms - radiotherapy
• ISSN: 0179-7158; 1439-099X
• DOI: 10.1007/s00066-023-02047-z

Purpose The aim of this study was to analyze the heart dose for left-sided breast cancer that can be achieved during daily practice in patients treated with multicatheter brachytherapy (MCBT) accelerated partial-breast irradiation (APBI) and deep-inspiration breath-hold (DIBH) whole-breast irradiation (WBI) using a simultaneous integrated tumor bed boost (SIB)—two different concepts which nonetheless share some patient overlap. Materials and methods We analyzed the nominal average dose (Dmean) to the heart as well as the biologically effective dose (BED) and the equivalent dose in 2‑Gy fractions (EQD2) for an α/β of 3 in 30 MCBT-APBI patients and 22 patients treated with DIBH plus SIB. For further dosimetric comparison, we contoured the breast planning target volume (PTV) in each of the brachytherapy planning CTs according to the ESTRO guidelines and computed tangential field plans. Mean dose (Dmean), EQD2 Dmean, and BED Dmean for three dosing schemes were calculated: 50 Gy/25 fractions and two hypofractionated regimens, i.e., 40.05 Gy/15 fractions and 26 Gy/5 fractions. Furthermore, we calculated tangential field plans without a boost for the 22 cases treated with SIB with the standard dosing scheme of 40.05 Gy/15 fractions. Results MCBT and DIBH radiation therapy both show low-dose exposure of the heart. As expected, hypofractionation leads to sparing of the heart dose. Although MCBT plans were not optimized regarding dose to the heart, Dmean differed significantly between MCBT and DIBH (1.28 Gy vs. 1.91 Gy, p