Abstract
Purpose: The European Society of Radiation & Oncology and Advisory Committee on Radiation Oncology Practice (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.Conclusions: 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.
Highlights
In the United States and Europe, breast cancer is the one of the most common cancers, accounts for 30% of all new cancer diagnoses in women, and is the leading cause of cancer-related mortality in women worldwide [1,2,3].Over the past two decades, the use of breast reconstruction has increased steadily [4, 5]
This study aimed to evaluate and compare the dosimetric improvement, plan complexity, and delivery accuracy of ESTRO-ACROP guidelines-based (EA-TVD) and conventional guidelines-based (C-TVD) target volume delineation in postmastectomy radiation therapy (PMRT) using hypofractionated volumetric-modulated arc therapy (VMAT) after immediate breast reconstruction (IBR)-i
Fifteen consecutive patients with left breast cancer who underwent mastectomy with tissue expander placement followed by PMRT with an intent to replace the expander to IBR on a later date were retrospectively included in this study
Summary
In the United States and Europe, breast cancer is the one of the most common cancers, accounts for 30% of all new cancer diagnoses in women, and is the leading cause of cancer-related mortality in women worldwide [1,2,3].Over the past two decades, the use of breast reconstruction has increased steadily [4, 5]. In the United States and Europe, breast cancer is the one of the most common cancers, accounts for 30% of all new cancer diagnoses in women, and is the leading cause of cancer-related mortality in women worldwide [1,2,3]. Breast reconstruction provides essential psychosocial, cosmetic, and quality of life benefits to patients with breast cancer who have undergone mastectomy [5, 7]. A meta-analysis of patient data from 22 randomized trials conducted by the Early Breast Cancer Trialists’ Collaborative Group showed that postmastectomy radiation therapy (PMRT) in patients with axillary dissection reduced breast cancer recurrence and mortality [8]. Miyashita et al reported the decrease in locoregional recurrence of breast cancer due to PMRT in patients with 1–3 positive axillary lymph nodes [9]
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