Canine Prostate Cancer: Current Treatments and the Role of Interventional Oncology

Prostate carcinoma is one of the most common cancers worldwide in men, with over 3 million men currently living with prostate carcinoma. In men, routine screening and successful treatment schemes, including radiation, prostatectomy, or hormone therapy, have allowed for high survivability. Dogs are recognized as one of the only mammals to spontaneously develop prostate neoplasia and are an important translational model. Within veterinary medicine, treatment options have historically been limited in efficacy or paired with high morbidity. Recently, less invasive treatment modalities have been investigated in dogs and people and demonstrated promise. Below, current treatment options available in dogs and people are reviewed, as well as a discussion of current and future trends within interventional treatment for canine PC.

Procedural description and prospective evaluation of short-term outcome for the use of prostatic artery embolization in dogs with carcinoma of the prostate

OBJECTIVE

To describe the procedure of prostatic artery embolization (PAE) in dogs with prostatic carcinoma and to evaluate the short-term outcome for treated dogs.

ANIMALS

20 client-owned dogs with prostatic carcinomas between May 2014 and July 2017.

PROCEDURES

In this prospective cohort study, dogs with carcinoma of the prostate underwent PAE with fluoroscopic guidance. Before and after PAE, dogs underwent CT and ultrasonographic examinations of the prostate, and each owner completed a questionnaire about the dog's clinical signs. Results for before versus after PAE were compared.

RESULTS

Prostatic artery embolization was successfully performed in all 20 dogs. Tenesmus, stranguria, and lethargy were significantly less common 30 days after PAE (n = 2, 1, and 0 dogs, respectively), compared with before PAE (9, 10, and 6 dogs, respectively). Median prostatic volume was significantly less 30 days after PAE (14.8 cm3; range, 0.4 to 48.1 cm3; interquartile [25th to 75th percentile] range, 6.7 to 19.5 cm3), compared with before PAE (21.7 cm3; range, 2.9 to 77.7 cm3; interquartile range, 11.0 to 35.1 cm3). All dogs had a reduction in prostatic volume after PAE, with a median prostatic volume loss of 39.4% (95% CI, 20.3% to 59.3%).

CONCLUSIONS AND CLINICAL RELEVANCE

Prostatic artery embolization was associated with decreased prostate volume and improved clinical signs in this cohort. The short-term response to PAE appears promising, and evaluation of the long-term impact on survival time is needed.

Prostate artery chemoembolization in prostate cancer: A proof of concept study in spontaneous prostate cancer in a canine model

PURPOSE

The purpose of this study was to assess the feasibility and efficacy of docetaxel-loaded bead chemoembolization in spontaneous prostate cancer in a canine model.

MATERIALS AND METHODS

Five pet dogs with histopathologically proven prostate cancer were referred for prostate artery chemoembolization (PACE). After PACE, all animals were followed, including pharmacokinetic study and clinical and biological evolution, until death. Pelvic contrast-enhanced computed tomography examination was performed at one and two months. Animals were subjected to pathological examination after death.

RESULTS

Both prostate arteries were successfully chemoembolized in all dogs. A median dose of 18 mg (Q1, Q3; 11.8, 20 mg) docetaxel loaded in 3 mL of 50-100 µm super absorbent polymer beads was injected into each dog. At one month, four of the five dogs were still alive and the median prostate volume was 51% lower (prePACE median prostate volume, 18.4 mL [Q1, Q3; 12, 32.1 mL] vs. postPACE median prostate volume, 6.2 mL [Q1, Q3; 6.2, 11 mL]). At two months, three dogs died because of disease progression. The two remaining dogs showed a 70% median decrease in prostate volume. Prostate pathological examination showed 73% of necrosis. No worsening of urinary symptoms was observed. Pharmacokinetic analysis showed limited systemic passage of docetaxel. All dogs died of metastatic spread at nine months.

CONCLUSION

This study suggests that PACE is feasible and safe for the treatment of spontaneous prostate cancer in a canine model and may provide a new approach to treat selected patients with prostate cancer.

Yttrium-90 Radioembolization to the Prostate Gland: Proof of Concept in a Canine Model and Clinical Translation

PURPOSE

To investigate the feasibility, safety, and absorbed-dose distribution of prostatic artery radioembolization (RE) in a canine model.

MATERIALS AND METHODS

Fourteen male castrated beagles received dihydroandrosterone/estradiol to induce prostatic hyperplasia for the duration of the study. Each dog underwent fluoroscopic prostatic artery catheterization. Yttrium-90 (⁹⁰Y) microspheres (TheraSphere; Boston Scientific, Marlborough, Massachusetts) were delivered to 1 prostatic hemigland (dose escalation from 60 to 200 Gy), with the contralateral side serving as a control. Assessments for adverse events were performed throughout the follow-up (Common Terminology Criteria for Adverse Events v5.0). Positron emission tomography/magnetic resonance (MR) imaging provided a confirmation after the delivery of absorbed-dose distribution. MR imaging was performed before and 3, 20, and 40 days after RE. Tissue harvest of the prostate, rectum, bladder, urethra, penis, and neurovascular bundles was performed 60 days after RE.

RESULTS

All the animals successfully underwent RE. Positron emission tomography/MR imaging demonstrated localization to and good coverage of only the treated hemigland. No adverse events occurred. The MR imaging showed a significant dose-dependent decrease in the treated hemigland size at 40 days (25%-60%, P < .001). No extraprostatic radiographic changes were observed. Necropsy demonstrated no gross rectal, urethral, penile, or bladder changes. Histology revealed RE-induced changes in the treated prostatic tissues of the highest dose group, with gland atrophy and focal necrosis. No extraprostatic RE-related histologic findings were observed.

CONCLUSIONS

Prostate ⁹⁰Y RE is safe and feasible in a canine model and leads to focal dose-dependent changes in the gland without inducing unwanted extraprostatic effects. These results suggest that an investigation of nonoperative prostate cancer is warranted.

The application of prostate artery embolization in the management of intractable prostate bleeding

Introduction

Prostate cancer is one of the most common malignancies affecting European men. Sequelae of the advanced malignancy require invasive procedures which may not be eligible especially for old, debilitated patients. The aim of this manuscript is to review the outcomes of prostate artery embolization in the management of refractory bleeding.

Material and methods

A PubMed database search was done for all English language articles on prostate artery embolization in prostate cancer, published between 2003 and 2019. For current review, information related to number, age of the patients, aetiology of the hematuria, bilateral or unilateral procedure, type of embolic material, technical and clinical success, complications, recurrent hematuria, hematocrit and hemoglobin levels were analyzed.

Results

A total of 10 original full-text comparative and non-comparative (case series) studies were reviewed. Minor complications described in the literature ranged from 10–50%. After prostate artery embolization, the recurrence of the haematuria occurred in 10–57% of the patients. Moreover, prostate artery embolization successfully treated lower urinary tract symptoms and urinary retention in prostate cancer patients.

Conclusions

The procedure appears safe, burdened with low risk of complications and accomplishes technical and clinical success. It is a promising option for patients with hemorrhage, but due to the scarcity of data further investigations are needed.

Prostatic artery embolization with polyethylene glycol microspheres: evaluation in a canine spontaneous benign prostatic hyperplasia model

BACKGROUND

Prostatic artery embolization (PAE) is a minimally invasive technique for the management of symptomatic benign prostatic hyperplasia (BPH) relieving the lower urinary tract symptoms in patients. Various embolic agents have been tested in animal models and subsequently used in human patients. The purpose of this study was to evaluate the technical feasibility, effectiveness, and safety of PAE with polyethylene glycol microspheres in a canine spontaneous BPH model.

RESULTS

Five adult male Beagle dogs (4.78 ± 1.11 years) were diagnosed by tranrectal ultrasonography of spontaneous BPH (prostate volume > 18 ml) and underwent PAE with polyethylene glycol microspheres (400 ± 75 μm). PAE procedures were performed successfully in all dogs. After PAE, all dogs were inspected for potential procedure-related complications during 1 month of follow-up. No major complications were observed any animal. Follow-up angiography was performed in each animal at 1 month of follow-up. Recanalization was demonstrated in all the embolized prostatic arteries or main branches at the end of the study. Magnetic Resonance Imaging (MRI) evaluations were performed immediately before PAE as baseline data, and 1 week, 2 weeks and 1 month after PAE. MRI study showed that the prostate shrank substantially with ischemic necrosis in each dog. There was a significant reduction in the mean prostate volume at 2 weeks and 1 month compared with the baseline data, from 19.95 ± 1.89 mL to 13.14 ± 2.33 and 9.35 ± 2.69 mL (p < 0.001), respectively. Histopathological study was conducted after 1-month follow-up angiography and confirmed the therapeutic responses with diffuse glandular atrophy and interstitial fibrosis.

CONCLUSIONS

The findings of the present study support that PAE with the use of polyethylene glycol microspheres is a safe and feasible procedure that may induce a significant shrinkage of prostate due to the local ischemia and secondary glandular atrophy. Early recanalization of target arteries remains to be further addressed in both laboratory investigation and clinical practice.

Prostatic artery embolization: Progress and prospect

Prostate artery embolization is a well-known and promising treatment for benign prostatic hyperplasia, with the quantum leaps of research in medicine. We aim to provide an up-to-date review of the novel technique, including large retrospective studies and randomized control trials, ends with discussions of advantages and disadvantages of this minimally invasive technique.

An updated meta-analysis of prostatic arterial embolization versus transurethral resection of the prostate in the treatment of benign prostatic hyperplasia

OBJECTIVE

To investigate whether prostatic arterial embolization (PAE) could be recommended as a routine therapy for benign prostatic hyperplasia (BPH), we conducted an updated meta-analysis to assess the efficacy and safety of PAE compared with transurethral resection of the prostate (TURP).

METHODS

Systematic literature retrieval by searching data from Web of science, Pubmed, Embase, Cochrane Library, ClinicalTrial.gov, CNKI, Wanfang and VIP databases was carried out to identify all related trials from the inception dates to June 2019. We also conducted subgroup analyses depending on the kind of study design, kind of PAE and kind of TURP.

RESULTS

Nine studies comparing PAE with TURP involving a total of 860 BPH patients were selected. Postoperative reduced IPSS score (MD 2.50; 95% CI 0.78-4.21; P = 0.004), postoperative reduced QOL score (MD 0.40; 95% CI 0.09-0.71; P = 0.01), postoperative reduced PV (MD 8.59; 95% CI 4.74-12.44; P < 0.00001) and postoperative increased Q_max (MD 2.54; 95% CI 1.02-4.05; P = 0.001) were better in TURP than in PAE; however, PAE was associated with lower sexual dysfunction rate (OR 0.24; 95% CI 0.15-0.39; P < 0.00001) compared with TURP. Meanwhile, no significant difference in postoperative reduced PVR (MD 0.46; 95% CI - 2.08 to 3.00; P = 0.72) and complication (OR 0.57; 95% CI 0.21-1.55; P = 0.27) between PAE and TURP group was demonstrated.

CONCLUSION

PAE was inferior to TURP in the improvement of postoperative IPSS, QOL, PV, Q_max and TURP still remained the gold standard. However, PAE may be a valuable alternative to TURP in the treatment of BPH patients who refuse surgery or with surgery contraindication.

Introduction of prostate artery embolization (PAE) in Sweden

Background: Transurethral resection of the prostate (TURP) is 'Gold Standard' treatment for moderate-to-severe lower urinary tract symptoms (LUTS) due to benign prostate hyperplasia (BPH) with bladder-outlet obstruction (BOO). However, TURP is associated with a risk of complications, so minimally invasive methods have been developed. Prostate artery embolization (PAE) is a new minimally invasive procedure. This study reports the outcomes of PAE when introduced in a 'real life' clinical setting in a Swedish County hospital. Methods: A prospective, single-center, single-arm study in a consecutive vascular-anatomy 'all comers' population, eligible for TURP or adenomaenukleation, but unsuitable for this, treated with PAE from January 2015 to June 2018. Defined improvement of IPSS/QoL scores, or freedom from urinary catheter if previous urinary catheter-dependent, or clean intermittent catheterization (CIC) were considered as clinically successful treatments. PAE was performed until arterial stasis using the Perfected technique. Most patients were treated during a day-care procedure. Results: Of 37 treated men, bilateral PAEs were achieved in 32 patients, unilateral PAEs in four patients, and bilateral failure in one patient due to difficult vascular anatomy. Clinically successful treatment was achieved in 84%, without serious adverse events. Conclusions: PAE was introduced in Sweden, showing PAE as a novel and good minimally invasive alternative in treatment of symptomatic BPH, possible to perform as a day-care procedure.

Transurethral resection of the prostate versus prostatic artery embolization in the treatment of benign prostatic hyperplasia: a meta-analysis

Background

To compare the clinical efficiency and safety of transurethral resection of the prostate (TURP) and prostatic artery embolization (PAE) for the treatment of Benign prostatic hyperplasia (BPH).

Methods

We searched PUBMED, EMBASE and the Cochrane Central Register for studies from May 1998 to May 2018 for studies comparing the efficiency and safety of TURP with PAE. Four studies met the inclusion criteria for our meta-analysis. After data extraction and quality assessment, we used RevMan 5.2 to pool the data.

Results

A total of four studies involving 506 patients were included in our meta-analysis. The pooled data showed that the Qmax was higher in TURP group than PAE with a significant difference (WMD:4.66, 95%CI 2.54 to 6.79, P < 0.05). The postoperative QOL was lower in the TURP than PAE group (WMD: -0.53, 95%CI -0.88 to − 0.18, P < 0.05). The postoperative prostate volume was significantly smaller in the TURP than PAE group (WMD: -8.26, 95%CI -12.64 to − 3.88, P < 0.05). The operative time was significantly shorter in the TURP than PAE group (WMD: -10.55, 95%CI -16.92 to − 4.18, P < 0.05). No significant difference was found in the postoperative IPSS and complications between TURP and PAE (P > 0.05, WMD:1.56, 95%CI -0.67 to 3.78, p = 0,05, OR:1.54, 95%CI 1.00 to2.38, respectively).

Conclusions

TURP could achieve improved Qmax and QoL compared to PAE. Therefore, for patients with BPH and lower urinary tract symptoms (LUTS), TURP was superior to PAE.

Lower Urinary Tract Neoplasia

Lower urinary tract neoplasia in companion animals is a debilitating and often life-threatening disease. Tumors of the bladder, urethra, and prostate often occur independently, although extension of these tumors into adjacent regions of the lower urinary tract is documented frequently. The most common lower urinary tract tumor in dogs and cats is transitional cell carcinoma (TCC). In both dogs and cats, TCC affecting the urinary bladder is generally considered to be highly aggressive with both local and metastatic disease potential, and this disease poses unique treatment challenges. Whereas much literature exists regarding the TCC disease process, treatment options, and prognosis in dogs, relatively few studies on feline TCC have been published due to the lower incidence of TCC in this species. Prostate tumors, most commonly adenocarcinomas, occur less commonly in dogs and cats but serve an important role as a comparative model for prostate neoplasia in humans. This article serves as a review of the current information regarding canine and feline lower urinary tract neoplasia as well as the relevance of these diseases with respect to their human counterparts.

Clinical evaluation of embolization of the superior vesical prostatic artery for treatment of benign prostatic hyperplasia: a single-center retrospective study

Introduction

Non-surgical minimally invasive treatments are greatly needed for patients with symptomatic benign prostatic hyperplasia (BPH), for whom medical treatment has failed and surgery is contraindicated. This study retrospectively evaluated the efficacy and safety of super-selective prostatic artery embolization (PAE) for BPH, relative to transurethral resection of the prostate (TURP).

Aim

To clinically evaluate the efficacy and safety of super-selective PAE for BPH, relative to TURP.

Material and methods

From February 2012 to March 2015, patients with BPH underwent selective PAE (n = 17) or TURP (control group; n = 40). Prostate volume, maximum urinary flow rate (Qmax), International Prostate Symptoms Score (IPSS), and quality of life (QoL) score were evaluated at baseline and postoperative 3, 6, and 12 months. Complications were also recorded.

Results

All the procedures were technically successfully. At postoperative 1 year, patients given PAE had significantly greater prostate volume (64.6 ±10.2 ml), IPSS (23.9 ±4.9), and QoL (4.1 ±0.7) compared with the control patients (42.0 ±7.5 ml, 13.1 ±3.5, and 2.1 ±0.7, respectively). The Qmax of the PAE group (9.5 ±3.7 ml/s) was significantly lower than that of the control (21.8 ±4.2 ml/s). The changes in parameters of the TURP patients relative to the preoperative baseline were significantly greater than those of the PAE group. No severe complications occurred.

Conclusions

Prostatic artery embolization was demonstrated as safe and effective and may be considered an alternative treatment for BPH patients, especially for those who are not candidates for or refuse surgery.

Canine prostate models in preclinical studies of minimally invasive interventions: part II, benign prostatic hyperplasia models

Canine prostate is widely used as animal model in the preclinical evaluation of emerging therapeutic interventions. Spontaneous benign prostatic hyperplasia (BPH) is common in adult intact male dogs with two distinct pathological types: glandular and complex form of prostatic hyperplasia. The complex form of prostatic hyperplasia, usually occurring in older dogs, represents an ideal model because of its unique pathologic feature, including not only glandular hyperplasia but also an increase in prostate stromal components. The limited commercial availability of adult dogs with spontaneous BPH motivates experimentally induced BPH in young dogs. Hormone-induced canine BPH model has been well established with various hormonal treatment regimens and administration approaches. The goal of this review is to provide the veterinary background in spontaneous BPH in dogs, summarize the techniques in hormonal induction of canine BPH, and highlight the pathological and clinical limitations of the canine models that may lead to distinct therapeutic responses compared to clinical trials in humans.

Benign prostatic hyperplasia after prostatic arterial embolization in a canine model: A 3T multiparametric MRI and whole-mount step-section pathology correlated longitudinal study

PURPOSE

To explore the morphological and functional characteristics of prostatic arterial embolization (PAE) in a canine model of benign prostatic hyperplasia (BPH) with 3T multiparametric magnetic resonance imaging (mp-MRI) and whole-mount step-section pathology correlation.

MATERIALS AND METHODS

Eight adult male beagle dogs with hormone-induced BPH underwent 3T mp-MRI before and 1, 3, and 6 months after PAE, with subsequent whole-mount step-section pathologic assessment. Images were acquired using T₁ -weighted images (T₁ WI), T₂ WI, 3D-SPACE, diffusion-weighted imaging (DWI), susceptibility-weighted imaging (SWI), T₂ -mapping, and dynamic contrast-enhanced (DCE) sequences. Variance analysis was performed to assess statistical differences in prostatic volume (PV), apparent diffusion coefficient (ADC), and T₂ values. Pearson correlation analysis was performed to correlate ADC, T₂ , and PV.

RESULTS

The PV decreased from baseline to 1, 3, and 6 months after PAE from (25.88 ± 7.09) cm³ to (6.48 ± 2.08) cm³ , (6.48 ± 3.39) cm³ , (6.20 ± 2.88) cm³ . The ADC values sequentially decreased from baseline to 1, 3, and 6 months after PAE from (1497.06 ± 222.72) × 10^-6 mm² /s to (1056.00 ± 189.46) × 10^-6 mm² /s, (950.48 ± 77.85) × 10^-6 mm² /s, (980.98 ± 107.78) × 10^-6 mm² /s. The T₂ values decreased from baseline to 1, 3, and 6 months after PAE were (83.74 ± 5.29) msec, (68.72 ± 5.66) msec, (53.96 ± 15.04) msec, (49.81 ± 13.34) msec, respectively. ADC and T₂ values were positively correlated with PV (r = 0.823 and 0.744, respectively). Microhemorrhages and hemosiderin were found on SWI after PAE.

CONCLUSION

3T mp-MRI may facilitate noninvasive assessment of morphological and functional changes of BPH after PAE.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1220-1229.

Prostate Artery Embolization for Benign Prostatic Hyperplasia: Current Status

Prostate artery embolization has garnered much attention as a promising treatment for lower urinary tract symptoms secondary to benign prostatic hyperplasia. We aim to provide an up-to-date review of this minimally invasive technique, including discussion of potential benefits and technical challenges. Current evidence suggests it is a safe and effective option for patients with medication-refractory urinary obstructive symptoms who are poor surgical candidates or refuse surgical therapy. Larger, randomized studies with long-term follow-up data are needed for this technique to be formally established in the treatment paradigm for benign prostatic hyperplasia.

Efficacy and safety of prostate artery embolization on lower urinary tract symptoms related to benign prostatic hyperplasia: a systematic review and meta-analysis

Background

Prostate artery embolization (PAE) is emerging and is a promising minimally invasive therapy that improves lower urinary tract symptoms (LUTS) related to benign prostatic hyperplasia (BPH). The purpose of this article was to evaluate the efficacy and safety of PAE on LUTS related to BPH.

Materials and methods

A literature review was performed to identify all published articles of PAE for BPH. The sources included MEDLINE, EMBASE and Cochrane Library from 1980 to 2016. A systematic review and meta-analysis was conducted. The outcome measurements were combined by calculating the mean difference with 95% confidence interval. Statistical analysis was carried out using Review Manager 5.3.0.

Results

Twelve studies involving 840 participants were included. Compared with baseline, the International Index of Erectile Function (IIEF-5; International Prostate Symptom Score) scores, the quality of life scores, peak urinary flow rate (Q_max) and postvoid residual volume all had significant improvements during the 24-month follow-up (all P<0.00001). Both prostate volume (PV) and prostate-specific antigen had significant decrease during the 12-month follow-up (P<0.00001 and P=0.005, respectively), except postoperative 24 months (P=0.47 and P=0.32, respectively). The IIEF-5 short form scores had significant increase at postoperative 6 months (P=0.002) and 12 months (P<0.0001), except postoperative 1 month (P=0.23) and 24 months (P=0.21). For large volume (PV ≥80 mL) BPH, the results were similar. There were no life-threatening complications.

Conclusion

PAE is an effective, safe and well-tolerable treatment for LUTS related to BPH, including large volume (PV ≥80 mL) BPH, with a good short-term follow-up. Studies with large number of cases and longer follow-up time are needed to validate our results.

Review of Current Literature for Prostatic Artery Embolization

Prostatic artery embolization (PAE) is an emerging, novel interventional technique in the management of patients with lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH). BPH is a common clinical condition in middle-aged and elderly men resulting in LUTS, including nocturia, urinary frequency, urgency, decreased urinary flow rates, hesitancy, and incomplete bladder emptying. Traditionally, LUTSs have been managed by medical or surgical therapies. Since the initial incidental discovery that selective PAE performed for uncontrolled bleeding secondary to BPH resulted in improved LUTS, the technique has continually evolved with a growing body of evidence supporting its safety and efficacy. However, despite the available data, PAE has yet to be established as a standard-of-care treatment option for patients with LUTS/BPH. In this article, the authors review the history and current state of PAE, including published data from case reports, animal studies, retrospective/prospective cohort studies, and prospective randomized controlled trials.

Prostatic Arterial Embolization with Small Sized Particles for the Treatment of Lower Urinary Tract Symptoms Due to Large Benign Prostatic Hyperplasia: Preliminary Results

Background:

The clinical failure after prostatic artery embolization (PAE) with conventional particles was relatively high, in treatment for lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH). We reported the results of PAE with combined polyvinyl alcohol particles 50 μm and 100 μm in size as a primary treatment in 24 patients with severe LUTS secondary to large BPH.

Methods:

From July 2012 to June 2014, we performed PAE in 24 patients (65–85 years, mean 74.5 years) with severe LUTS due to large BPH (≥80 cm³) and refractory to medical therapy. Embolization was performed using combination of 50 μm and 100 μm in particles size. Clinical follow-up was performed using the International Prostate Symptom Score (IPSS), quality of life (QoL), peak urinary flow (Q_max), postvoid residual (PVR) volume, the International Index of Erectile Function (IIEF), prostatic specific antigen (PSA), and prostatic volume measured by magnetic resonance imaging at 1, 3, 6, and every 6-month thereafter. Technical success was defined when PAE was completed in at least one pelvic side. Clinical success was defined as the improvement of both symptoms and QoL. A Student's t-test for paired samples was used.

Results:

PAE was technically successful in 22 patients (92%). Bilateral PAE was performed in 19 (86%) patients and unilateral in 3 (14%) patients. Follow-up data were available for 22 patients observed for mean of 14 months. The clinical improvement at 1, 3, 6, and 12-month was 91%, 91%, 88%, and 83%, respectively. At 6-month follow-up, the mean IPSS, QoL, PVR, and Q_max were from 27 to 8 (P = 0.001), from 4.5 to 2.0 (P = 0.002), from 140.0 ml to 55.0 ml (P = 0.002), and from 6.0 ml/s to 13.0 ml/s (P = 0.001), respectively. The mean prostate volume decreased from 110 cm³ to 67.0 cm³ (mean reduction of 39.1%; P = 0.001). The PSA and IIEF improvements after PAE did not differ from pre-PAE significantly. No major adverse events were noted.

Conclusions:

The combination of 50 μm and 100 μm particles for PAE is a safe and effective treatment method for patients with severe LUTS due to large BPH, which further improves the clinical results of PAE.

Prostatic Artery Embolization (PAE) for Symptomatic Benign Prostatic Hyperplasia (BPH): Part 2, Insights into the Technical Rationale

Rationale of prostatic artery embolization (PAE) in the treatment of symptomatic benign prostatic hyperplasia is conventionally believed to include two parts: shrinkage of the enlarged prostate gland as a result of PAE-induced ischemic infarction and potential effects to relax the increased prostatic smooth muscle tone by reducing the number and density of α1-adrenergic receptor in the prostate stroma. This review describes new insights into the likely mechanisms behind PAE, such as ischemia-induced apoptosis, apoptosis enhanced by blockage of androgens circulation to the embolized prostate, secondary denervation following PAE, and potential effect of nitric oxide pathway immediately after embolization. Studies on therapeutic mechanisms in PAE may shed light on potentially new treatment strategies and development of novel techniques.

Current Status of Prostate Artery Embolization for Lower Urinary Tract Symptoms: Review of World Literature

Prostate artery embolization has emerged as a promising treatment for lower urinary tract symptoms secondary to benign prostatic hyperplasia. However, although it has gained increasing attention in radiology literature, it remains under-reported from a urologic perspective. We aim at providing an up-to-date review of this minimally invasive technique. Evidence suggests it is a promising and effective option for patients with large prostate volumes, multiple comorbidities, and suboptimal results from pharmacotherapy. Larger, randomized studies with longer follow-up periods are needed for this technique to be formally established in the urology community.

MRI findings after prostatic artery embolization for treatment of benign hyperplasia

OBJECTIVE

The purpose of this article is to assess and describe the MRI findings after prostatic artery embolization for treatment of benign prostatic hyperplasia.

MATERIALS AND METHODS

We retrospectively evaluated 17 patients who underwent prostatic artery embolization as part of different prospective studies to evaluate this alternative treatment of benign prostatic hyperplasia. Clinical results were evaluated by assessment of urinary catheterization and International Prostate Symptom Score (IPSS). Serial MRI examinations were performed, and the prostatic central gland and peripheral zone were evaluated for signal intensity changes and the presence and characteristics of infarcted areas. Statistical analysis was performed with ANOVA for repeated measures and Student t test.

RESULTS

All patients had clinical success, as defined by the removal of indwelling urinary catheter or decreased IPSS after embolization. Infarcts were seen in 70.6% of the subjects, exclusively in the central gland, were almost always characterized by hyperintensity on T1-weighted images and predominant hypointensity on T2-weighted images, and became smaller (mean reduction, p < 0.001) and isointense to the remaining of the central gland over time. Volume reduction of the prostate after embolization was significant (averaging 32.0% after 12-18 months; p < 0.001) only in patients with infarcts. No statistically significant association was seen between the development of infarcts and IPSS.

CONCLUSION

MRI can be used for assessing the development of infarcts and volume reduction in the prostate after embolization. Further studies are needed to correlate these findings to clinical outcome.

The "PErFecTED technique": proximal embolization first, then embolize distal for benign prostatic hyperplasia

Prostatic artery embolization requires a refined technique to achieve good imaging and clinical success. The PErFecTED (Proximal Embolization First, Then Embolize Distal) technique has produced greater prostate ischemia and infarction than previously described methods with clinical improvement of lower urinary symptoms and lower recurrence rates. The microcatheter should cross any collateral branch to the bladder, rectum, corpus cavernosum, gonad, or penis and be placed distally into the prostatic artery before its branching to the central gland and peripheral zone. This technique allows better distribution of embolic material in the intraprostatic arteries and reduces risk of spasm or thrombus. Because benign prostatic hyperplasia develops primarily in the periurethral region of the prostate, the urethral group of arteries should be embolized first. Subsequent distal investigation and embolization completes occlusion and stasis of blood flow to the prostatic parenchyma. Since we added the second step to the PErFecTED technique, we have observed infarcts in all patients submitted to prostatic artery embolization.

Embolization therapy for benign prostatic hyperplasia: influence of embolization particle size on gland perfusion

PURPOSE

To assess the influence of embolic size on the therapy response of prostatic arterial embolization (PAE) based on perfusional changes seen on dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Twelve beagles underwent PAE, four dogs with each particle size: A: 100-300 μm; B: 300-500 μm; and C: 500-700 μm. Prior to and 1 month after the embolization all dogs underwent prostate DCE MRI.

RESULTS

After embolization, time to maximal perfusion intensity for prostate parenchyma increased in B (188 vs. 135 sec, P = 0.023) and C (200 vs. 120 sec, P = 0.001), while it did not change for A (139 vs. 124 sec, P = 0.39). The maximal relative intensity increased after embolization in C (3.84 vs. 2.38, P < 0.001), while it did not change for A (2.50 vs. 2.44, P = 0.36) and B (3.23 vs. 2.9, P = 0.21). The extent of visualized intraprostatic urethral wall increased after embolization in B compared with A and C, 239.5 ± 138.1% vs. 56.1 ± 34.3, P = 0.04. Enhancement changes correlated with prostate volume changes: prostate volumes in A decreased less as compared with B and C (77 ± 34% vs. 56 ± 14%), P = 0.02.

CONCLUSION

The enhancement and morphological data are useful to monitor response to therapy after embolization. Embolization with 300-500 and 500-700 μm particle may provide better results than with 100-300 μm particles in a canine model.