Why the study?
Deep-inspiration breath-hold reduces cardiac radiation exposure but requires compliance, and 4D-CT robust optimization had not been evaluated for cardiac substructure sparing or in VMAT to optimize treatment for noncompliant patients.
Does 4D-CT robust optimization improve cardiac and substructure sparing compared to DIBH and conventional 4D-CT in left-sided breast cancer radiotherapy?
Does 4D-CT robust optimization improve cardiac and substructure sparing compared to DIBH and conventional 4D-CT in left-sided breast cancer radiotherapy?
4D robust optimization is clinically feasible for limiting cardiac and substructure doses during free-breathing radiotherapy, though DIBH IMRT remains the optimal technique for heart sparing in left-sided breast cancer.
BACKGROUND: Adjuvant whole-breast radiotherapy (RT) is a significant part of the standard of care treatment after breast cancer (BC) conserving surgery. Modern techniques including intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) have constituted to better target coverage and critical organs sparing. However, BC survivors are at risk of developing radiation-induced cardiac toxicity. Hence, deep-inspiration breath-hold (DIBH) techniques have been implemented at many centers to further reduce cardiac exposure but require compliance. 4D-CT robust optimization can account for heart intrafractional motion per breathing phase. The optimization has been explored in cardiac sparing of breast IMRT compared to DIBH in a small sample size but has not been evaluated in substructures sparing, nor in VMAT. To provide patients who are not compliant to breath-hold with an optimal treatment approach, various heart sparing techniques need to be evaluated for statistical significance and clinical feasibility. AIM: This retrospective study aimed to provide an extensive dosimetric heart sparing comparison of free-breathing, 4D-CT-based treatment planning, including robust optimization with DIBH-based treatment planning. Combinations of forward and inverse IMRT and VMAT are also considered. METHODS: Lung. RESULTS: Heart were significantly reduced in inverse IMRT average 4D-CT compared to average 4D-CT VMAT (p < 0.02) and in 4D robust IMRT compared to 4D robust VMAT (p < 0.04). CONCLUSION: This study demonstrated the clinical feasibility of 4D robust optimization in limiting the cardiac and substructures dose during free-breathing RT with both IMRT/VMAT for patients who are not compliant with breath-hold RT. However, this study also presents that 4D robust optimization can reduce LAD dose but not fully outperform DIBH or conventional 4D-CT-based planning with IMRT/VMAT in heart sparing in treating early staged left-sided BC patients.
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Chau et al. (2022) studied this question.
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