Stereotactic ablative radiotherapy (SABR) offers improved tumor control, lees number of treatments, and reduced toxicity compared with conventional therapies. The role of SABR continues to expand. Fiducial markers are required to guide SABR.Traditionally CT guided or surgical placement had been used to facilitate the delivery of stereotactic radiotherapy. EUS-guided fiducial marker placement has been introduced as a safe and feasible alternate method. We share our experience with the two types of the fiducial delivery system & evolution of applications & technique. The back loaded fiducial needles (BLFS), which need to be inserted to the needle by hand, is cumbersome, more prone for needle stick injury to the operator, and time consuming. A novel preloaded system (PLFS) delivers 2 fiducials per needle and can be interchanged with the FNB needle enabling biopsies in the same setting. The preloaded system has an automatic safety shield enabling safety during needle exchange. With advance of Endoscopic oncology, a trained advanced endoscopist can implant fiducials in a variety of solid organ tumors accessible by EUS and needing SABR.
We conducted a retrospective review of our experience from 2015-2017. We started using fiducials in late half of 2015 and changed to PLFS in early 2016. We reviewed our experience on the total procedure time (TPT) with the BLFS with PLFS. The PLFS allows for ease of application. After the switch to PLFS, through conversations with radiation oncology, we reviewed the extension of the technology to additional applications outside the pancreas.
The mean total procedure time TPT with the back loaded system was 31.68 min, while the mean TPT with the preloaded system was 22.68min, a 30% reduction in the total procedural time for pancreatic cases. (Table 1) We then evolved use of the PLFS to place fiducials in other solid tumors such as mediastinal lesions with lung CA, esophagus, cholangiocarcinoma. (Table 2). No migration of fiducials were noted during the mapping for radiotherapy in either cohort, and all patients successfully received SABR. No bleeding or other adverse events were noted.
We believe that the endoscopic interventional community should adopt the use of PLS systems and work with radiation oncology to expand the use of EUS guided fiducial placement to solid malignancies that are accessible through EUS. This will reduce the number of interventions, the lag time to treatment and overall cost.