“In the same way that a study is not needed to show that jumping out of a plane with a parachute yields better outcomes than without, there is no need to prove that glue has technical advantages over particles.”
This was a statement made by Romaric Loffroy (University of Dijon School of Medicine, Dijon, France) during an animated debate with Clare Bent (University Hospitals Dorset, Bournemouth, UK) on liquid embolics for prostate artery embolization (PAE) at the recent Global Embolization Symposium and Technologies (GEST; 15–18 May, New York, USA). Countering Loffroy’s eagerness for glue to be assumed into the healthcare algorithm, Bent’s tack called for better data and dispelled ‘hypotheses’ which assume glue’s beneficial effect.
Loffroy’s first argument addressed the question that, if particles work, why change? In his view, “the main issue with particles—the Achilles heel and the reason we have recanalisation in most cases—is the lack of durability”, which has necessitated a “more aggressive and more robust initial optimisation”, namely PAE with glue, he stated. Illustrating this, he referenced Tiago Bilhim et al’s 2022 finding which showed a 58.1% reintervention rate at 10 years in patients who underwent PAE with polyvinyl alcohol particles.
“Would we keep the TV in black and white? No, because the standard is something to be changed all the time,” said Loffroy. Although data concerning glue are limited, Loffroy admitted, he contended that glue has ample technical benefits over particles, including real-time visibility, which reduces the risk of non-target embolization, and provides a clearer endpoint.
While glue has a “learning curve” and its use should not be first attempted during PAE, Loffroy averred, comparative studies have found no significant difference in complication rates between glue and particles. Better yet, as newer glues emerge, he added that delayed polymerisation capabilities support better control thus reducing complication rates.
Lastly, set to disprove those who say glue is ‘too expensive’, Loffroy asked: “What is your time worth? What about radiation exposure? What about recanalisation and recurrence?” He stated that the cost of glue in Asia and Europe is less than that of particles, totalling €350 for 1ml of Glubran 2 (GEM) and 10ml of Lipiodol (Guerbet) in France where he practises. “How can you get any cheaper than that?” said Loffroy.
Summarising, the presenter stated that there is “no need to wait for a randomised controlled trial or 10-year follow-up data showing that glue has advantages over particles. It’s faster, cheaper, more visible, has a lower radiation dose and lower rate of recanalisation—with even better long-term clinical outcomes in my experience,” he rounded off.
Loffroy’s opponent, Bent began by describing the risk of promoting a technique with little evidence to prove its efficacy: “My first anxiety around liquids for PAE is that we have 20 years’ worth of data, five randomised controlled trials, 10 years of follow-up, all focused on the role of PAE to treat enlarged prostates using particles and microspheres; yet, our urology colleagues remain sceptical, and their respective societies still recommend that PAE continue under investigational use. If we introduce a modification to the technique, such as liquids, are we really using robust evidence to promote that? Are we going to undermine and compromise PAE?”
Bent first highlighted the heterogeneity of glue, warning against using the “blanket term” ‘glue PAE’ as results seen in the literature to date show variable outcomes depending on material type. Divergent outcomes in trials have most commonly been due to the differing polymerisation kinetics, observed Bent. As some brands of glue polymerise quickly, Bent described that risks could range from proximal embolization, trapping of the catheter, or an exothermic reaction that can cause “significant inflammation and pelvic pain”.
In terms of clinical benefit, she acknowledged that, between glue and particles, the limited data available have shown early outcomes are comparable but clarified that glue appears to offer a more conservative reduction in prostate size in the shorter term. Bent highlighted that reports have observed a 16–21% prostate size reduction with glue at three-month follow-up versus 30–40% with microspheres, which may influence embolic choice when performing PAE for other indications including neoadjuvant PAE prior to brachytherapy.
Drawing on her own practice with Glubran 2, Bent specified that glue does reduce radiation dose as the embolic injection is “quick”, but, that this does not mean the procedure itself is fast, particularly if using a plug and push technique for a more aggressive endpoint. “You don’t get immediate occlusion—that is not correct,” said Bent, displaying a case which illustrates extensive re-distribution of a glue embolic at four minutes post embolization. She stated that, yes, visibility is good; however, it is only “hypothesised” that glue’s improved visibility equates to less non-target embolization. In fact, a study by Etienne Salet et al found that both glue and particles caused glans necrosis in an equal number of patients, Bent shared.
“So, at what point are we saying that glue is better than particles?” asked Bent rhetorically. Her argument, erring on the side of adherence to evidence and caution against employing techniques without a solid basis for efficacy, concluded that PAE should only be used in the context of a trial. “It’s an exciting concept, but glue PAE isn’t quite ready for prime time just yet,” stated Bent.
