Implementation of Online Adaptive Radiotherapy for Breast Cancer Patients on Ethos (BREAST-ART)

Implementation of Online Adaptive Radiotherapy for Breast Cancer Patients on Ethos

Postoperative radiotherapy is for the majority of breast cancer patients the standard of care. During postoperative radiotherapy, unexpected dosimetric deviations can occur due to breast contour changes resulting from resorption of postoperative breast or chest wall seroma/hematoma, oedema either postoperatively or during irradiation, or arm/body positioning variation. In approximately 10% of cases, repositioning after setup imaging is not sufficient, and offline plan adaptation is required. When a new treatment planning is required in the standard offline workflow this will take in general 2 days. By using an online adaptive workflow with a daily treatment planning this delay and extra work caused by offline plan adaptation can be omitted. The aim of this study is to translate the offline adaptive workflow to an online adaptive workflow, and investigate the experiences of patients who have been treated with online adaptive radiotherapy for breast cancer (BREAST-ART).

In this single-arm prospective BREAST-ART study breast cancer patients with an indication for postoperative radiotherapy will be treated according to the Dutch and institutional guidelines. Target volumes will be the whole breast, chest wall, axillary levels, tumor bed boost and partial breast irradiation on the right side and left side with a deep inspiration breath hold technique. Robust templates are developed for offline and online treatment planning with an IMRT tangential multiple-beam setup. A simulation of the online adaptive workflow is performed in breast cancer patients already treated on the Ethos-linac with the standard offline adaptive workflow. Patients will be treated following the online adaptive workflow delivered on the Ethos-Linac. Patient experience will be evaluated using an in-house developed questionnaires after the first and last fraction, scoring treatment satisfaction on a 4-point Likert scale. Furthermore, all dosimetric data, volume details, DICOM images and the time spend on all parts of the online adaptive workflow will be evaluated.

Inclusion Criteria:

• Breast cancer patients referred for postoperative radiotherapy of the breast, chest wall, axillary levels, tumor bed boost or partial breast irradiation.
• Age of 18 years and older.
• Adequate understanding and communicating the Dutch language.
• Written informed consent for use of routinely collected clinical data and to fill out questionnaires.

Exclusion Criteria:

• Patients not suitable for postoperative radiotherapy