A Retrospective Dosimetric Analysis of the New ESTRO-ACROP Target Volume Delineation Guidelines for Postmastectomy Volumetric Modulated Arc Therapy After Implant-Based Immediate Breast Reconstruction

Abstract

ESTRO-ACROP) presented new guidelines for clinical target volume (CTV) delineation in post-mastectomy radiation therapy (PMRT) after implant-based immediate breast reconstruction (IBR-i). This study evaluated the dosimetric characteristics, dosimetric accuracy, and delivery accuracy of these guidelines in volumetric modulated arc therapy (VMAT).Methods and Materials: This retrospective study included 15 patients with left breast cancer who underwent mastectomy with tissue expander placement followed by PMRT. An experienced radiation oncologist delineated the CTV twice on the same image datasets based on the ESTRO-ACROP (EA-TVD) and conventional target volume delineation (C-TVD) guidelines. All VMAT plans, which used a double partial arc, were generated using six MV photons. Clinically relevant dose-volume parameters for organs at risk were compared. Dosimetric accuracy of the treatment plans and delivery accuracy were assessed.Results: Target volume of EA-TVD was significantly smaller than that of C-TVD. Although no statistically significant difference was noted in the target coverage between the two VMAT plans, EA-TVD VMAT significantly reduced the mean heart dose (3.99 ± 1.02 vs. 5.84 ± 1.78 Gy, p = 0.000), the maximum left anterior descending coronary artery (LAD) dose (9.43 ± 3.04 vs. 13.97 ± 6.04 Gy, p = 0.026), and the mean LAD dose (4.52 ± 1.31 vs. 6.35 ± 2.79 Gy, p = 0.028) compared with C-TVD VMAT. No significant difference was observed with respect to the total monitor units, plan complexity, and delivery quality assurance.Chang et al. Dosimetric Analysis of Two GuidelinesConclusions: This is the first study to show significant dose reduction for the normal heart and LAD tissue offered by the EA-TVD, while maintaining dosimetric and delivery accuracy, in PMRT after IBR-i in VMAT for left-sided breast cancer patients.

Dosimetric evaluation of VMAT and helical tomotherapy techniques comparing conventional volumes with clinical target volumes based on new ESTRO ACROP post-mastectomy with immediate implant reconstruction contouring guidelines

“…Chang et al compared the dosimetric characteristics of VMAT plans generated based on conventionally delineated clinical target volumes and volumes contoured according to ESTRO ACROP guidelines. Fifteen left-sided PMRT with IBR patients were included in this study and mammaria interna lymph nodes were covered within the target volume [ 22 ]. Hypofractionated regimen was used to a total dose of 40.05 Gy in 15 fractions.…”

“…In contrast to our study, they also reported lower mean heart doses (3.99 ± 1.02 vs. 5.84 ± 1.78 Gy, p = 0.000), however, these doses were obtained at the cost of higher CB doses. [ 22 ].…”

Retrospective dosimetric comparison of VMAT versus t-IMRT for patients with carbon dioxide tissue expanders undergoing left sided PMRT using the recent ESTRO-ACROP target volume delineation

“…With the introduction of the 2019 ESTRO-ACROP consensus guidelines for volume delineation when treating PMRT after implantbased immediate reconstruction, 1 we envisage there may be clinicians who are keen to implement this when presented with a patient who has this ATED in-situ, given the potential to significantly reduce dose to cardiac structures when compared to conventional target volumes. 13 Minimising RT dose to the heart is well known to be beneficial when it comes to reducing the risk of major coronary or other cardiac events. 19,20 This study shows that acceptable RT plans can be generated if needing to treat left sided PMRT, targeting the chest wall and regional nodes, using DIBH and VMAT or t-IMRT technique.…”

“…[10][11][12] The European Society of Radiation & Oncology and Advisory Committee on Radiation Oncology Practice (ESTRO-ACROP) in 2019 published a consensus guideline for target volume delineation of the chest wall for PMRT in the setting of immediate breast reconstruction, tailored to the location of the implant, 1 which will likely be increasingly utilised in the future, especially in the setting of modern RT planning techniques. It has been shown by Chang et al 13 to lead to VMAT plans with significantly lower dose to heart and left anterior descending coronary artery when compared to conventional target volume delineations which include the whole implant. The decision to include or exclude internal mammary node (IMN) in the treatment volumes continues to be a topic of clinical controversy in node positive breast cancer.…”

Impact of radiation dose on complications among women with breast cancer who underwent breast reconstruction and post-mastectomy radiotherapy: A multi-institutional validation study

“…Recently, ESTRO ACROP consensus guideline for target volume delineation for patients who received post mastectomy radiotherapy after implant-based immediate reconstruction for early stage breast cancer was published [10]. Subsequent dosimetric studies are perfomed using the new guideline, including one study which showed significant dose reduction for normal heart and left anterior descending artery with the new target volume [31]. More studies reporting the association with the new guideline and reconstruction complications are anticipated.…”