Feasibility of a novel liquid fiducial marker for use in image guided radiotherapy of oesophageal cancer

Objective:: To evaluate the feasibility of a new liquid fiducial marker for use in image-guided radiotherapy for oesophageal cancer.

Methods:: Liquid fiducial markers were implanted in patients with metastatic or inoperable locally advanced oesophageal or gastro-oesophageal junction cancer receiving radiotherapy. Markers were implanted using a conventional gastroscope equipped with a 22 G Wang needle. Marker visibility was evaluated on fluoroscopy, CT, MRI and cone beam CT scans.

Results:: Liquid markers (n = 16) were injected in four patients. No Grade 2 or worse adverse events were observed in relation to the implantation procedure, during treatment or in the follow-up period. 12/16 (75%) markers were available at the planning CT-scan and throughout the treatment- and follow-up period. The implanted markers were adequately visible in CT and cone beam CT but were difficult to distinguish in fluoroscopy and MRI without information from the corresponding CT image.

Conclusion:: Liquid fiducial marker placement in the oesophagus proved safe and clinically feasible.

Advances in knowledge:: This paper presents the first clinical use of a new liquid fiducial marker in patients with oesophageal cancer and demonstrates that marker implantation using standard gastroscopic equipment and subsequent use in three-dimensional image-guided radiation therapy is safe and clinically feasible.