Dosimetric comparison between interstitial brachytherapy and volumetric-modulated arc therapy for tumor bed boost in breast cancer

Abstract

To dosimetrically compare high-dose-rate interstitial brachytherapy (HDR-BT) with volumetric-modulated arc therapy (VMAT) for tumor bed boost, following breast conservative treatment.Material and methods: 50 patients with early-stage breast cancer who underwent breast conservation surgery, followed by either HDR-BT (n = 25) of 15 Gy in 6 fractions over a period of 3 days, or VMAT dose of 16 Gy in 8 fractions (n = 25) for tumor bed boost, were retrospectively reviewed. All patients received whole breast irradiation of 46 Gy in 23 fractions. Dosimetric parameters for organs at risk (OARs), including ipsilateral and contralateral lungs, heart, contralateral breast, skin, and ribs, were evaluated with the help of dose-volume histograms (DVH).Results: Heart sparing was similar in both modalities (left-sided breast irradiation, HDR-BT D 2cc 20.5% vs. VMAT 30.2%, p-value = 0.243; right-sided breast irradiation, D 2cc 6.5% vs. 4.4%, p-value = 0.165). Left-sided cases received higher dose to heart compared to right-sided patients. Interstitial brachytherapy resulted in significantly less dose to contralateral breast (D 2cc 4.3% vs. 9.6%, p-value < 0.0001), ipsilateral lung (D 2cc 27.6% vs. 73.2%, p-value < 0.0001), contralateral lung (D 2cc 4.2% vs. 14.5%, p-value < 0.0001), ribs (D 2cc 24.1% vs. 41.2%, p-value < 0.0001), and skin (D 2cc 77.3% vs. 95%, p-value < 0.0001).Conclusions: HDR-BT-based tumor bed boost irradiation results in significantly lower doses to most organs at risk with similar heart sparing compared to VMAT.

Extreme hypofractionation in radiation therapy for patients with early breast cancer: what is the optimal technique?

“…Compared with VMAT technique, MCIB has been shown to deliver significantly less radiation doses to the contralateral breast, ipsilateral and contralateral lung, heart and ribs at least in the breast tumour bed boost setting 22 . The investigators of the HEARTBEAT study have therefore chosen MCIB as the treatment technique of choice to investigate extreme hypofractionation.…”

“…Compared with VMAT technique, MCIB has been shown to deliver significantly less radiation doses to the contralateral breast, ipsilateral and contralateral lung, heart and ribs at least in the breast tumour bed boost setting. 22 The investigators of the HEARTBEAT study have therefore chosen MCIB as the treatment technique of choice to investigate extreme hypofractionation. Recognising the importance of meticulous attention to optimal dose distribution, it therefore aims to achieve these strict dosimetric specifications: The study workflow involves identification of eligible patients in the breast multi-disciplinary team meeting, initial consultation with a study investigator, followed by a technical eligibility ultrasound scan (USS) and computed tomography (CT) scan.…”

Predictors of poor cosmesis in breast cancer patients treated with adjuvant whole breast radiation therapy plus high-dose-rate interstitial brachytherapy boost after breast conservation surgery

“…For a shallow target, if the breast contour is roughly flat and beam obliquity can be avoided, en-face low energy electron beam is the preferred technique, as electron beam obliquity reduces its' therapeutic range and increases the skin absorbed dose [6]. In deep-seated tumor beds (depth ≥ 4 cm), modern image-guided multicatheter interstitial brachytherapy boost in comparison with other boost modalities, such as high energy electron beams or advanced external beam photon techniques (e.g., intensity modulated radiation therapy [IMRT] or volumetric modulated arc therapy [VMAT]), can better protect nearby healthy organs from high doses of radiation, and therefore are an excellent modality for dose escalation [6][7][8].…”

The value of brachytherapy in the age of advanced external beam radiotherapy: a review of the literature in terms of dosimetry

“…Boost doses following whole-breast irradiation can also be effectively delivered with BT [19,75]. Charagvandi et al [18] have dosimetrically compared single-fraction ablative RT with interstitial BT and VMAT K [17] 3D-CRT, HT 13 BT 10, 5, 0 Margin: 3D-CRT 10 mm, supine HT 5 mm, prone HT 0 mm Charagvandi [18] VMAT 20 VMAT NR Single-fraction ablative radiotherapy Terheyden [19] 3D-CRT 136 Two patient cohorts NR Boost was given to 36 patients with BT and to 100 with 3D-CRT Major [20] IMRT 34 BT 5 4-5 coplanar beams for IMRT Shahbazian [21] 3D-CRT 15 BT 5 Deeply seated tumours Fröhlich [22] SBRT with CK 25 CK 2 Virtual BT plans on CTs with contours for CK Herein [23] SBRT with CK 32 Two patient cohorts 2 Comparison between real treatment plans Periasamy [24] VMAT 50 Two patient cohorts 5 Tumour bed boost after whole-breast irradiation Gynaecological Georg [25] IMRT, IMPT 9 BT 3-5 High-tech EBRT vs. high-tech BT Shwetha [26] IMRT 10 BT NR Pear-shaped dose distribution of BT mimicked by IMRT Gielda [27] HT 6 BT 0 3-5 mm CTV-PTV margin for BT and HT Sharma [28] IMRT 12 BT 3-5 Interstitial BT vs. IMRT for cervical cancer Cengiz [29] SBRT with CK 11 BT 0 BT with a tandem and two ovoids with dosimetry on point A Neumann [30] CK 11 CK + real BT patients 0 Emulating BT-like inhomogeneous dose distributions Khosla [31] IMRT 15 BT and IMRT 10 Two series of CT scans, one for BT and one for IMRT Otahal [32] CK 10 BT 0 MRI-based intracavitary and interstitial BT Pinzi [33] IMRT 15 BT 7-10 BT and IMRT for boost only Wali [34] VMAT 10 BT 5 Boost with VMAT in replacing BT Jones [35] SBRT with HT 15 BT 2 Endometrium, 2 mm CTV-PTV margin in HT plans Kauffmann [36] 3D-Arc and SBRT [20]. For 34 patients with early-stage breast cancer treated with interstitial HDR-BT, additional IMRT plans were created using identical CT data and contours.…”