DIBH reduces right coronary artery and lung radiation dose in right breast cancer loco-regional radiotherapy

Ebony Gough; Simon Ashworth; Trevor Moodie; Wei Wang; Karen Byth; Rachael Beldham-Collins; Jacqueline Buck; Samer Ghattas; Lucinda Burke; Kirsty E Stuart

doi:10.1016/j.meddos.2024.03.002

DIBH reduces right coronary artery and lung radiation dose in right breast cancer loco-regional radiotherapy

Med Dosim. 2024 Apr 6:S0958-3947(24)00016-5. doi: 10.1016/j.meddos.2024.03.002. Online ahead of print.

Authors

Affiliations

¹ Department of Radiation Oncology, Crown Princess Mary Cancer Centre, Westmead Hospital, Westmead, NSW 2145, Australia; Department of Radiation Oncology, Blacktown Cancer and Haematology Centre, Blacktown Hospital, Blacktown, NSW 2148, Australia.
² Department of Radiation Oncology, Crown Princess Mary Cancer Centre, Westmead Hospital, Westmead, NSW 2145, Australia; Sydney Medical School, C24-Westmead Hospital, The University of Sydney, Sydney, New South Wales, Australia; Westmead Breast Cancer Institute, Westmead Hospital, Sydney, New South Wales, Australia.
³ NHMRC Clinical Trials Centre, The University of Sydney, Camperdown, NSW 2050, Australia; Research and Education Network, Western Sydney Local Health District, Westmead Hospital, Westmead, NSW 2145, Australia.
⁴ Clinical Trials, Nepean and Blue Mountains Cancer Care Centre, Nepean Hospital, Kingswood, NSW 2747, Australia.
⁵ Department of Medical Radiology, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia.
⁶ Department of Radiation Oncology, Chris O'Brien Lifehouse, Royal Prince Alfred Hospital, Camperdown, NSW, 2050, Australia.
⁷ Department of Radiation Oncology, Crown Princess Mary Cancer Centre, Westmead Hospital, Westmead, NSW 2145, Australia; Sydney Medical School, C24-Westmead Hospital, The University of Sydney, Sydney, New South Wales, Australia; Westmead Breast Cancer Institute, Westmead Hospital, Sydney, New South Wales, Australia. Electronic address: Kirsty.Stuart@health.nsw.gov.au.

PMID: 38584019
DOI: 10.1016/j.meddos.2024.03.002

Abstract

To determine whether deep inspiratory breath-hold (DIBH) reduces dose to organs-at-risk (OAR), in particular the right coronary artery (RCA), in women with breast cancer requiring right-sided post-mastectomy radiotherapy (PMRT) including internal mammary chain (+IMC) radiotherapy (RT). Fourteen consecutive women requiring right-sided PMRT + IMC were retrospectively identified. Nodal delineation was in accordance with European Society for Radiology and Oncology (ESTRO) guidelines and tangential chest wall fields marked. Patients were planned with Anisotropic Analytical Algorithm using free-breathing (FB) and DIBH datasets. Dose was calculated using Acuros External Beam algorithm. FB and DIBH dose comparisons were analyzed for heart, RCA and right lung, as were chest wall and IMC planning target volumes (PTVs). DIBH vs FB resulted in median decreases of: the RCA mean dose by 0.6Gray (Gy) (interquartile range (IQR) 0.1, 1.9) (p = 0.002), RCA max dose by 1.8Gy (IQR 0.8, 6.1) (p = 0.002), and V5Gy by 2.9% (IQR 0.0, 37.2) (p = 0.016). RCA data indicated no statistically significant dosimetric reduction ≥10Gy. A median reduction of 1.7Gy (c -0.0, 7.1) (p = 0.019) in maximum heart dose was recorded with DIBH vs FB; no significant difference was observed in other heart and left anterior descending coronary artery parameters. The median reduction in right lung mean dose was 2.8Gy for DIBH vs FB plans (IQR 1.6, 3.6) (p = 0.001); significant median reductions of V5Gy, V20Gy, and V30Gy were all achieved with DIBH. Chest wall PTV coverage did not significantly differ between DIBH and FB plans; IMC dosimetric coverage improved with use of DIBH (V47.5Gy, V45Gy, V42Gy). DIBH reduced OAR dose in right-sided PMRT + IMC patients. A novel finding was that DIBH decreased RCA dose. Heart and right lung dose were also decreased with DIBH, whilst optimally dosed PTVs were maintained.

Keywords: Breast cancer; DIBH; Heart dose; Lung dose; Right coronary artery; Right-sided.