Cardiac Substructure Dose and Survival in Stereotactic Radiotherapy for Lung Cancer: Results of the Multi-Centre SSBROC Trial

V Chin; P Chlap; R Finnegan; E Hau; A Ong; X Ma; J Descallar; J Otton; L Holloway; G P Delaney; S K Vinod

doi:10.1016/j.clon.2024.07.005

Cardiac Substructure Dose and Survival in Stereotactic Radiotherapy for Lung Cancer: Results of the Multi-Centre SSBROC Trial

Clin Oncol (R Coll Radiol). 2024 Oct;36(10):642-650. doi: 10.1016/j.clon.2024.07.005. Epub 2024 Jul 20.

Authors

V Chin¹, P Chlap², R Finnegan³, E Hau⁴, A Ong⁵, X Ma⁶, J Descallar⁷, J Otton⁸, L Holloway⁹, G P Delaney², S K Vinod²

Affiliations

¹ University of New South Wales, South Western Sydney Clinical School, Sydney, Australia; Liverpool and Macarthur Cancer Therapy Centres, Department of Radiation Oncology, Sydney, Australia; Ingham Institute for Applied Medical Research, Sydney, Australia; University of Sydney, Image X Institute, Sydney, Australia. Electronic address: [email protected].
² University of New South Wales, South Western Sydney Clinical School, Sydney, Australia; Liverpool and Macarthur Cancer Therapy Centres, Department of Radiation Oncology, Sydney, Australia; Ingham Institute for Applied Medical Research, Sydney, Australia.
³ Ingham Institute for Applied Medical Research, Sydney, Australia; Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, Australia; University of Sydney, Institute of Medical Physics, Sydney, Australia.
⁴ Crown Princess Mary Cancer Centre, Westmead Hospital, Department of Radiation Oncology, Sydney, Australia; Blacktown Haematology and Cancer Centre, Blacktown Hospital, Department of Radiation Oncology, Sydney, Australia; Westmead Institute of Medical Research, Centre for Cancer Research, Sydney, Australia; University of Sydney, Westmead Clinical School, Sydney, Australia.
⁵ Crown Princess Mary Cancer Centre, Westmead Hospital, Department of Radiation Oncology, Sydney, Australia.
⁶ St George Hospital, Division of Cancer Services, Sydney, Australia.
⁷ University of New South Wales, South Western Sydney Clinical School, Sydney, Australia; Ingham Institute for Applied Medical Research, Sydney, Australia.
⁸ University of New South Wales, South Western Sydney Clinical School, Sydney, Australia; Liverpool Hospital, Department of Cardiology, Sydney, Australia.
⁹ University of New South Wales, South Western Sydney Clinical School, Sydney, Australia; Liverpool and Macarthur Cancer Therapy Centres, Department of Radiation Oncology, Sydney, Australia; Ingham Institute for Applied Medical Research, Sydney, Australia; University of Sydney, Institute of Medical Physics, Sydney, Australia.

PMID: 39097416
DOI: 10.1016/j.clon.2024.07.005

Abstract

Background and purpose: Stereotactic ablative body radiotherapy (SABR) is increasingly used for early-stage lung cancer, however the impact of dose to the heart and cardiac substructures remains largely unknown. The study investigated doses received by cardiac substructures in SABR patients and impact on survival.

Materials and methods: SSBROC is an Australian multi-centre phase II prospective study of SABR for stage I non-small cell lung cancer. Patients were treated between 2013 and 2019 across 9 centres. In this secondary analysis of the dataset, a previously published and locally developed open-source hybrid deep learning cardiac substructure automatic segmentation tool was deployed on the planning CTs of 117 trial patients. Physical doses to 18 cardiac structures and EQD2 converted doses (α/β = 3) were calculated. Endpoints evaluated include pericardial effusion and overall survival. Associations between cardiac doses and survival were analysed with the Kaplan-Meier method and Cox proportional hazards models.

Results: Cardiac structures that received the highest physical mean doses were superior vena cava (22.5 Gy) and sinoatrial node (18.3 Gy). The highest physical maximum dose was received by the heart (51.7 Gy) and right atrium (45.3 Gy). Three patients developed grade 2, and one grade 3 pericardial effusion. The cohort receiving higher than median mean heart dose (MHD) had poorer survival compared to those who received below median MHD (p = 0.00004). On multivariable Cox analysis, male gender and maximum dose to ascending aorta were significant for worse survival.

Conclusions: Patients treated with lung SABR may receive high doses to cardiac substructures. Dichotomising the patients according to median mean heart dose showed a clear difference in survival. On multivariable analyses gender and dose to ascending aorta were significant for survival, however cardiac substructure dosimetry and outcomes should be further explored in larger studies.

Keywords: Automatic segmentation; Cardiac substructures; Lung cancer; Stereotactic radiotherapy; Survival outcome.

Publication types

Multicenter Study
Clinical Trial, Phase II

MeSH terms

Aged
Aged, 80 and over
Australia
Carcinoma, Non-Small-Cell Lung* / mortality
Carcinoma, Non-Small-Cell Lung* / pathology
Carcinoma, Non-Small-Cell Lung* / radiotherapy
Carcinoma, Non-Small-Cell Lung* / surgery
Female
Heart / radiation effects
Humans
Lung Neoplasms* / mortality
Lung Neoplasms* / pathology
Lung Neoplasms* / radiotherapy
Lung Neoplasms* / surgery
Male
Middle Aged
Organs at Risk / radiation effects
Prospective Studies
Radiosurgery* / methods
Radiotherapy Dosage