The aim of prostate artery embolisation for benign prostatic hyperplasia is to reduce the blood supply of the prostate gland, causing some of it to undergo necrosis with subsequent shrinkage.
Benign prostatic hyperplasia (BPH) is one of the most common diseases affecting older men. It affects up to 20% of men in their 40s, and this increases with age to 90% of men in their 70s.(1) Histologically, it is characterised by a progressive non-malignant proliferation of stromal and epithelial cells in the central zone of the prostate.(2) It is associated with a symptom complex known as lower urinary tract symptoms (LUTS). These include urinary hesitancy, weak stream, increased frequency, nocturia, erectile dysfunction and incontinence. In addition, complications include repeated urinary tract infections, bladder stones and acute urinary retention. These symptoms and potential complications can frequently have a significant effect on quality of life, sleep pattern and carrying out daily activities.(3)
Established treatments
The principal aim of BPH treatments is symptomatic relief that reduces the impact on patients’ lives of the associated LUTS.(3) Those with only very mild symptoms may be managed with conservative management and regular follow up. For those with moderate to severe symptoms the mainstay of management has been split into medical, minimally invasive and surgical management.(2) Medical management principally involves long term use of alpha-blockers and/or 5-alpha-reductase inhibitors. Alpha blockers work by relaxing smooth muscles within the prostate and bladder neck to increase flow and the reduce bladder outflow obstruction caused by BPH.
5-alpha-reductase inhibitors act by inhibiting the conversion of testosterone to its more potent version, dihydrotestosterone, which promotes prostate growth.(4) Minimally invasive treatments include microwave and needle ablation techniques as well as stents and trans-prostatic implants to hold the prostatic channel open. Laser ablation (green light and Holmium Laser) use laser energy to vaporise, resect or enucleate the prostatic tissue and give similar give similar results to transurethral resection of the prostate (TURP) but with less blood loss.(2,5) The most common surgical treatment of BPH is TURP, which involves surgical removal of the centre of the prostate via a transurethral route.(6)
What is prostate artery embolisation?
Embolisation is a well established minimally invasive technique that involves blockage of blood vessels by introducing a variety of substances, known as embolics. It is a technique that has been used for many years in the treatment of a variety pathologies, but is principally used to treat haemorrhage and both benign and malignant tumours.(7) Prostate artery embolisation is a new method for treating BPH that was first described in 2000, and which is performed by interventional radiologists.(8) It first involves accessing the right common femoral artery in the groin percutaneously under local anaesthetic using needles and catheters.
X rays and contrast injections are then used to guide micro-catheters into the prostatic arteries. Once within the prostatic arteries small particles are injected into the prostate.(9) These block the blood vessels in the prostate causing ischaemia of the prostatic tissues, a reduction in prostatic volume and resulting in an improvement in symptoms.(10) This process is performed on prostatic arteries bilaterally or unilaterally and requires a high degree of technical skill on the part of the interventional radiologist to perform.
Outcomes of PAE
Following its first description, PAE for BPH has been pioneered by interventional radiology groups undertaking early studies in Brazil and Portugal. Further studies are also underway elsewhere in the world, including the US and UK. The first UK study is currently being run at the University Hospital Southampton.
The results of these early studies have been very promising. The symptoms related to BPH are usually assessed in studies of medical and surgical treatments via the use of a variety of internationally validated patient questionnaires including the International Prostate Symptom Score (IPSS), Quality Of Life scores (QOL) and International Index of Erectile Function score (IIEF). Functional effects can also be assessed by urodynamic studies including flow rate and post-void residual urinary volumes.(3)
A preliminary study in 2010 by Carnevale et al in only two patients with acute urinary retention secondary to BPH showed relief of their obstructive symptoms and significant decreases in their prostatic volumes over the following months of 47.8% for the patient who underwent bilateral PAE and 27.8% or the patient who underwent unilateral PAE.(11)
A larger study by Pisco et al published in 2011 involved 15 patients with symptomatic BPH. This had a technical success rate of 93.3%. In a follow up of 7.9 months, there was an improvement in the IPSS score of 6.5 points, QOL improvement of 1.14 points and IIEF score of 1.7 points. Urinary flow increased 3.85ml/sec and there was a decrease in prostatic volume of 26.5ml.(10)
A study of 11 patients with BPH and indwelling catheters had a technical success rate of 75% and a rate of clinical success of 91% with catheter removal and symptom improvement.(12) The largest study published to date involved 255 patients, a mean follow up of ten months and follow up of up to 36 months; this had a technical success rate of 97.9% and a clinical success rate of 72% at 36 months.(13)
Risks and potential complications
In the published literature PAE appears to have a low morbidity and complication rate. In the largest series published involving 255 patients there was only one major complication. This was due to non-target embolisation of the bladder wall; this resulted in a small area of necrosis that was removed by simple surgery one month later and the patient made a good recovery. Other minor adverse events/complications in this study included urethral burning sensation 9.2%, UTI 7.6%, transient haematuria 5.6%, transient haematospermia 0.4%, minor rectal bleeding 2.4%, balanitis 1.6% and acute urinary retention 2.4%. All of these adverse events were transient and self-limiting.(13)
The main risk from the literature is that a subset of patients, for reasons that are currently unclear, do not derive a clinical benefit from PAE. In the above study 28% of patients did not derive a sustained clinical benefit from undergoing PAE.(13) Hopefully, with time and further research, we will be better able to predict those who are most likely to benefit from this procedure.
Advantages of PAE
PAE has several potential advances over the surgical alternatives. The procedure can be carried out as a day case, saving substantial costs and potentially limited bed spaces. It is performed using local anaesthetic and does not require a general or spinal anaesthetic; this once again reduces costs and allows it to be performed on patients who may not be fit enough for surgery/general anaesthesia.(9) In addition, the low complication rate and morbidity associated with PAE appears to be quite favourable compared with surgical options. Despite numerous recent developments in minimally invasive treatments, TURP remains the gold standard surgical treatment for BPH. This is associated with a range of potential complications including bleeding requiring blood transfusion, pain, infection, urethral stricture, bladder neck contracture, erectile dysfunction, incontinence and retrograde ejaculation.(14,15)
What is the future of PAE in the UK?
The first UK study of PAE for BPH is currently underway at Southampton General Hospital. We have now treated over 40 patients; our early results have been presented at several academic meetings but we hope to formally publish them in the coming months. Our early findings bear out similar results to those already published in the literature. In our first 35 patients, we have had a technical success rate of 100%, a reduction in IPSS score of 12 points, and an improvement in QOL of 3 points from 5 (unhappy) to 2 (mostly satisfied), a volume reduction of 42% and an increase in peak urinary flow of 32%.(16)
The British Society of Interventional Radiology (BSIR), British Association of Urological Surgeons (BAUS), the National Institute of Health and Care Excellence (NICE) and Cedar (a healthcare technology research centre) have recently come together to form the UK Registry of Prostate Embolisation (UK-ROPE). The purpose of this is to recruit over 100 patients over multiple centres to further assess the safety and efficacy of PAE and allow comparison with the surgical alternatives.(17)
Conclusions
PAE remains unproven, but early research is highly promising. As of yet its position in the pantheon of treatments for BPH has yet to be firmly established.(18) Further research and work is needed to answer numerous questions, for example, which patients are most likely to benefit, the best technique/embolic to use and what are its long term outcomes? Large multicentre, randomised, controlled, trials also need to be performed to compare its efficacy with the medical and surgical alternatives. Thanks to the work of BSIR, BAUS and NICE, the setting up of UK-ROPE should help ensure the UK remains at the forefront of work and research in this area.
Authors
David Flowers MB BCh BSc FRCR
Timothy Bryant BMedSci BMBS MRCP FRCR
John Coyne BM MRCS FRCR
Department of Interventional Radiology, University Hospital Southampton, UK
Jonathan Dyer BM FRCS (Urol)
Bhaskar Somani MRCS FEBU FRCS (Urol)
Mark Harris MB ChB FRCS (Urol) MD
Department of Urology, University Hospital Southampton, UK
Christopher Nigel Hacking MB BS FRCP FRCR
Department of Interventional Radiology, University Hospital Southampton, UK
References
- Arrighi HM et al. Natural history of benign prostatic hyperplasia and risk of prostatectomy. The Baltimore Longitudinal Study of Aging. Urology 1991;38(1 Suppl):4–8.
- Roehrborn CG. Benign prostatic hyperplasia: An overview. Rev Urol 2005;7(Suppl 9):S3–S14.
- Edwards JL. Diagnosis and management of benign prostatic hyperplasia. Am Fam Physician 2008;77(10):1403–10.
- Lepor H. Medical treatment of benign prostatic hyperplasia. Rev Urol 2011;13(1):20–33.
- Roehrborn CG et al. The prostatic urethral lift for the treatment of lower urinary tract symptoms associated with prostate enlargement due to benign prostatic hyperplasia: the L.I.F.T. Study. J Urol 2013;190(6):2161–7.
- Baazeem A, Elhilali MM. Surgical management of benign prostatic hyperplasia: current evidence. Nat Clin Pract Urol 2008;5(10):540–9.
- Coldwell DM, Stokes KR, Yakes WF. Embolotherapy: agents, clinical applications, and techniques. Radiogr Rev Publ Radiol Soc N Am Inc 1994;14(3):623–43; quiz 645–6.
- DeMeritt JS et al. Relief of benign prostatic hyperplasia-related bladder outlet obstruction after transarterial polyvinyl alcohol prostate embolization. J Vasc Interv Radiol JVIR 2000;11(6):767–70.
- Martins Pisco J et al. How to perform prostatic arterial embolization. Tech Vasc Interv Radiol 2012 Dec;15(4):286–9.
- Pisco JM et al. Prostatic arterial embolization to treat benign prostatic hyperplasia. J Vasc Interv Radiol JVIR 2011;22(1):11–19; quiz 20.
- Carnevale FC et al. Prostatic artery embolization as a primary treatment for benign prostatic hyperplasia: Preliminary results in two patients. Cardiovasc Intervent Radiol 2010;33(2):355–61.
- Carnevale FC et al. Quality of life and clinical symptom improvement support prostatic artery embolization for patients with acute urinary retention caused by benign prostatic hyperplasia. J Vasc Interv Radiol JVIR 2013;24(4):535–42.
- Pisco JM et al. Embolisation of prostatic arteries as treatment of moderate to severe lower urinary symptoms (LUTS) secondary to benign hyperplasia: results of short- and mid-term follow-up. Eur Radiol 2013;23(9):2561–72.
- Rassweiler J et al. Complications of transurethral resection of the prostate (TURP) – incidence, management, and prevention. Eur Urol 2006;50(5):969–79; discussion 980.
- Lee SW et al. Transurethral procedures for lower urinary tract symptoms resulting from benign prostatic enlargement: A quality and meta-analysis. Int Neurourol J 2013;17(2):59–66.
- Somani BK et al. Prostate artery embolization (PAE) for benign prostatic enlargement (BPE). BJU Int.2014; Feb 18; doi: 10.1111/bju.12672.
- BSIR UK-ROPE. (accessed 26 February 2014).
- National Institute for Health and Care Excellence. IPG453. Prostate artery embolisation for benign prostatic hyperplasia (BPH): guidance. (accessed 26 February 2014).
