BioXmark® liquid fiducials to enable radiotherapy tumor boosting in rectal cancer, a feasibility trial

Thirza J S Opbroek; Yves C P Willems; Frank Verhaegen; Rogier de Ridder; Chantal Hoge; Jarno Melenhorst; Frans Bakers; Heike I Grabsch; Jeroen Buijsen; Evert J Van Limbergen; Richard A M Canters; Maaike Berbée

doi:10.1016/j.ctro.2022.10.013

BioXmark® liquid fiducials to enable radiotherapy tumor boosting in rectal cancer, a feasibility trial

Clin Transl Radiat Oncol. 2022 Nov 4:38:90-95. doi: 10.1016/j.ctro.2022.10.013. eCollection 2023 Jan.

Affiliations

¹ Department of Radiation Oncology (Maastro), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center+, the Netherlands.
² Department of Gastroenterology, Maastricht University Medical Center+, the Netherlands.
³ Department of Surgery, Maastricht University Medical Center+, the Netherlands.
⁴ Department of Radiology, Maastricht University Medical Center+, the Netherlands.
⁵ Department of Pathology, Maastricht University Medical Center+, the Netherlands.
⁶ Division of Pathology and Data Analytics, Leeds Institute of Medical Research at St James's, University of Leeds, Leeds, UK.

Abstract

Background and purpose: Dose-escalation in rectal cancer (RCa) may result in an increased complete response rate and thereby enable omission of surgery and organ preservation. In order to implement dose-escalation, it is crucial to develop a technique that allows for accurate image-guided radiotherapy. The aim of the current study was to determine the performance of a novel liquid fiducial marker (BioXmark®) in RCa patients during the radiotherapy course by assessing its positional stability on daily cone-beam CT (CBCT), technical feasibility, visibility on different imaging modalities and safety.

Materials and methods: Prospective, non-randomized, single-arm feasibility trial with inclusion of twenty patients referred for neoadjuvant chemoradiotherapy for locally advanced RCa. Primary study endpoint was positional stability on CBCT. Furthermore, technical aspects, safety and clinical performance of the marker, such as visibility on different imaging modalities, were evaluated.

Results: Seventy-four markers from twenty patients were available for analysis. The marker was stable in 96% of the cases. One marker showed clinically relevant migration, one marker was lost before start of treatment and one marker was lost during treatment. Marker visibility was good on computed tomography (CT) and CBCT, and moderate on electronic portal imaging (EPI). Marker visibility on magnetic resonance imaging (MRI) was poor during response evaluation.

Conclusion: The novel liquid fiducial marker demonstrated positional stability. We provide evidence of the feasibility of the novel fiducial marker for image-guided radiotherapy on daily cone beam CT for RCa patients.

Keywords: IGRT; Liquid fiducial marker; Radiotherapy; Rectal cancer.