A small study comparing efficacy of four well-known embolic agents for UFE raises interesting questions and finds that outcomes with cheaper gelfoam were similar to those with Embospheres and Embozene in terms of infarction rates. Bead Block was shown to be less effective.
A prospective non-randomised single-centre study carried out between May 2006 and March 2009 by Nigel Hacking, Timothy Bryant and Brian Stedman in Southampton, UK, compared the clinical and radiological outcomes of uterine fibroid embolization (UFE) performed with either Bead Block, Embospheres, Embozenes or gelfoam.The study found that embolization with gelfoam resulted in comparable rates of complete dominant fibroid infarction with Embospheres and Embozene (85%, 90%, 95% respectively).Bead Block resulted in lower rates of complete dominant fibroid infarction (50%).
Results of the study were presented at the 35th Annual Scientific Meeting of the Society of Interventional Radiology, Tampa, USA.
The investigators concluded that “The choice of embolic agent used in UFE not only has an impact on radiological outcomes but has significant cost implications. Our small study has demonstrated similar outcomes for embolic agents of notably different cost.”
Timothy Bryant, Southampton University Hospital, who presented the study, told Interventional News: “This study was designed as a pilot study with the aim of guiding future larger randomised multicentre trials and as such the results have to be interpreted with this in mind. Certainly it has raised several interesting points. In our small group, gelfoam outcomes were similar to other more expensive embolics in terms of infarction rates. Increased rates of uterine artery occlusion were noted on follow-up in the gelfoam group which is in itself interesting considering that gelfoam is thought to be a temporary agent. The postulation is that this is related to vascular inflammation caused by the embolic, although we have no histological proof and the significance is not known. Considering this, perhaps gelfoam would be better used in the older patient cohort where there is less chance of having to reintervene and where fertility is less of an issue.”
Bryant also commented that gelfoam is not as amenable as spherical particulate embolics to injection through a microcatheter, which is a consideration given the increased usage of microcatheters amongst UFE practitioners.
Investigators included patients who presented with symptomatic fibroids suitable for UFE. The patients were then divided on a sequential basis into four groups of 20. UFE was carried out with either gelfoam (group I), Embospheres (group II), Bead Block (group III) or Embozenes (group IV).
Pelvic MRI was performed prior to UFE and at three to six months post-UFE. MRI included: T2W, unenhanced axial T1 FS, post gadolinium FS T1 and MRA sequences. Uterine volume, dominant fibroid volume, overall fibroid infarction, dominant fibroid infarction and uterine artery patency were assessed by MRI.
In groups treated with gelfoam, Embospheres and Embozenes (I, II, and IV), comparable rates of dominant fibroid complete infarction (85%, 90%, 95%) and overall complete fibroid infarction (70%, 80%, 70%) were seen.
With the group treated with Bead Block, investigators saw lower rates of dominant fibroid complete infarction (50%) and overall complete fibroid infarction (44%). Dominant fibroid volume reduction and uterine volume reduction were comparable between the groups. No correlation between VSS improvement and embolic agent or radiological outcome was demonstrated.
Commenting on the results, Bryant said, “Given the size of our study and lack of randomisation, it is difficult to draw definitive conclusions. The question is still wide open as to which is the most efficacious embolic, if in fact any are significantly better, in UFE. The fact that our gelfoam data supports what already exists in the literature in terms of satisfactory fibroid infarction rates makes it an attractive option, particularly within the older patient cohort.
“Also in respect to our trial there are other embolics that we have not yet investigated, including particulate PVA which is currently in widespread use in the UK and Canada and favourable on a cost basis,” he said.
“I think a large randomised multicentre trial is needed to answer these ongoing questions. The literature does show similar outcomes for many of the embolics in terms of fibroid infarction rates and symptomatic improvement, but there has been no large scale direct comparison. Other subsets such as periprocedural pain scores, volume of embolic required, post-procedural uterine artery patency, fertility, effect on ovarian function and post-embolization volume reduction should also be compared.”
Issue of cost
Bryant said, “There is a vast array of available embolic agents with a wide range of costs. The embolic is the most costly element of the UFE procedure and as such it is important to know that the one being used is both cost and clinically effective. Therefore informative comparative trials are essential to guide us.”
Nigel Hacking, principal investigator of the study said, “The message that gelfoam is an economical and effective alternative is particularly important in the developing world where I have set up a service in the Caribbean and have treated over 900 patients. I have also just set up a similar service in East Africa and am heading out there in April to treat the next batch of women. Gelfoam is all these countries can possibly afford and it is important that they do not think they are getting a cheap and ineffective option.”
Choice of embolic
Interventional News asked Bryant what advice he would give a young interventional radiologist looking to start embolization.
“Study the literature. There are a wide variety of embolics to choose from. They should pick the most appropriate for the case. Cost is a consideration, but the driving force should remain what is best for the patient. In general, for fibroid embolization the current consensus points towards the use of spherical embolics including Embospheres and Embozenes or particulate PVA. Despite ours and previous results, Robert Worthington-Kirsch’s recent study may also promote renewed interest in Beadblock using different sizes and endpoints from those formerly accepted. In the Far East there is widespread use of gelfoam in UFE with good results in the literature, but there is little in the way of evidence in the rest of the world. It is important to be aware that spherical embolics do not all have the same properties and as such have different size recommendations and embolization endpoints. This needs to be taken into account and the radiologist should be guided by the manufacturers’ recommendations when using their embolic to obtain the optimal results,” he said.
Robert Worthington-Kirsch, who presented comparative results for Embospheres and Bead Block at CIRSE 2008 commented: “Bead Block is softer than Embospheres so the same size is effectively a smaller sized particle. In my experience if you use the best technique, the two embolic agents combined with sensible endpoints, then you get identical optimum performance in embolization.”