Ectopic biomineralization in kidney stone formers compared to non-stone formers.

BACKGROUND: Kidney stone formers (SFs) are at increased risk of stroke, myocardial infarction, and atherosclerosis of the carotid and coronary arteries. These cardiovascular and urologic pathologies can result from ectopic biomineral deposition. The objectives of this study are: (I) to evaluate risk factors for ectopic biomineralization, and (II) to characterize the overall burden of ectopic minerals in known SFs compared to non-stone formers (NSFs) matched for these risk factors. METHODS: Presence and quantity of biominerals at eight anatomic locations (abdominal aorta, common iliac arteries, pelvic veins, prostate or uterus, mesentery, pancreas, and spleen) were determined in a case control study by retrospective analysis of clinical non-contrast computed tomography scans obtained from 190 SFs and 190 gender- and age-matched NSFs (renal transplant donors). Predictors of biomineralization were determined using negative binomial regression. A subgroup of 140 SFs and 140 NSFs were matched for risk factors for systemic biomineralization, and mineralization was compared between these matched SFs and NSFs using ordinal logistic regression. RESULTS: Hypertension, hyperlipidemia, diabetes mellitus, and smoking were more common amongst SFs. Risk factors for increased systemic biomineralization included history of nephrolithiasis, male gender, older age, and history of hyperlipidemia. When controlling for these comorbidities, SFs had significantly increased biomineralization systemically and at the abdominal aorta, iliac arteries, prostate, mesentery, pancreas, and spleen compared to NSFs. CONCLUSIONS: The current study provides evidence that SFs are at increased risk of biomineralization systemically, independent of common risk factors of atherosclerosis.

Open versus robotic partial nephrectomy: Systematic review and meta-analysis of contemporary studies.

OBJECTIVES: To compare perioperative outcomes of robotic-assisted partial nephrectomy (RaPN) with open partial nephrectomy (OPN). METHODS: Systematically search through PubMed, Embase, ClinicalKey, Cochrane Library, ProQuest, ScienceDirect, Web of Science, and ClinicalTrials.gov for eligible studies was performed to April 11, 2018. A meta-analysis was conducted for studies comparing RaPN and OPN. Confounding variables were assessed by meta-regression or subgroup analysis. RESULTS: This study included 34 studies with 60 808 patients. Meta-analysis revealed less blood loss, less transfusion, longer operative time, less postoperative complications, lower readmission rate, shorter length of stay, and less estimated glomerular filtration rate (eGFR) decline in RaPN groups. The superiority of RaPN in blood loss was attenuated with highly complex renal masses. The superiority of RaPN in intraoperative complications was strengthened with renal hilar control. The advantage of RaPN in surgical margin was increased in patient with body mass index (BMI) < 28. CONCLUSIONS: Compared with OPN, RaPN provided lower morbidities and better renal function preservation.

A continuum of mineralization from human renal pyramid to stones on stems.

The development of new modalities for kidney stone prevention rests upon understanding the progression of mineralization within the renal pyramid. The progression from small foci of mineralized volumes within the renal pyramid to larger interstitial plaques that ultimately lead into clinically detectable calcium-based stones on calcium phosphate stems will be presented through correlative microscopy approach. High resolution X-ray computed tomography (micro-XCT), electron microscopy, and energy dispersive X-ray (EDX) compositional analyses of interstitial plaques, stems, and attached stones were performed. Increase in mineral density progressed with mineralization severity, with the highest mineral densities detected within mature Randall's plaque and stems to which kidney stones were attached. EDX analyses revealed variable elemental composition within interstitial plaque, stems, and stones. Micro-XCT reconstructions of stones with stems enabled visualization of unoccluded tubules within stems, with average tubule diameters corresponding to thin limbs of Henle, blood vessels, and collecting ducts. Correlative microscopy confirmed that the progression of mineralization leading to calcium-based nephrolithiasis occurs through a continuum involving four anatomically and structurally distinct biomineralization regions: 1) proximal intratubular mineralization within the renal pyramid; 2) interstitial Randall's plaque near the tip of the papilla; 3) emerging plaque (stems); and, 4) the body of heterogeneous stones. STATEMENT OF SIGNIFICANCE: Nephrolithiasis is a common condition affecting nearly 1 in 11 Americans. The most common type of stone, calcium oxalate is known to form on a calcium phosphate deposit on the renal papilla known as Randall's plaque. Novel imaging techniques have identified distinct regions of biomineralization not just at the tip, but throughout the renal papilla. The classic understanding of Randall's plaque formation is reformulated using correlative imaging techniques. This study establishes a stepwise progression of anatomically-specific biomineralization events including, 1) proximal intratubular mineralization within the renal pyramid; 2) interstitial Randall's plaque near the tip of the papilla; 3) emerging plaque (stems); and, 4) the body of heterogeneous stones, and provides insights into the need for plausible site-specific therapeutic intervention.

Micro-Costing Analysis Demonstrates Comparable Costs for LithoVue Compared to Reusable Flexible Fiberoptic Ureteroscopes.

INTRODUCTION: Reusable ureteroscope durability and need for repair are significant sources of expense and inefficiency for patients and urologists. Utilization of LithoVue™, a disposable flexible digital ureteroscope, may address some of these concerns. To identify its economic impact on clinical care, we performed a micro-cost comparison between flexible reusable fiberoptic ureteroscopes (URF-P6™) and LithoVue. PATIENTS AND METHODS: For this prospective, single-center micro-costing study, all consecutive ureteroscopies performed during 1 week each in July and August 2016 utilized either URF-P6 or LithoVue ureteroscopes respectively. Workflow data were collected, including intraoperative events, postoperative reprocessing cycle timing, consumables usage, and ureteroscope cost data. RESULTS: Intraoperative data analysis showed mean total operating room time for URF-P6 and LithoVue cases were 93.4 ± 32.3 and 73.6 ± 17.4 minutes, respectively (p = 0.093). Mean cost of operating room usage per case was calculated at $1618.72 ± 441.39 for URF-P6 and $1348.64 ± 237.40 for LithoVue based on institutional cost rates exclusive of disposables. Postoperative data analysis revealed costs of $107.27 for labor and consumables during reprocessing for URF-P6 cases. The costs of ureteroscope repair and capital acquisition for each URF-P6 case were $957.71 and $116.02, respectively. The total ureteroscope cost per case for URF-P6 and LithoVue were $2799.72 and $2852.29, respectively. CONCLUSIONS: Micro-cost analysis revealed that the cost of LithoVue acquisition is higher per case compared to reusable fiberoptic ureteroscopes, but savings are realized in labor, consumables, and repair. When accounting for these factors, the total cost per case utilizing these two ureteroscopes were comparable.

Variation in Radiologic and Urologic Computed Tomography Interpretation of Urinary Tract Stone Burden: Results From the Registry for Stones of the Kidney and Ureter.

OBJECTIVE: To compare the measured stone burden recorded between urologists and radiologists, and examine how these differences could potentially impact stone management. As current urologic stone surgery guideline recommendations are based on stone size, accurate stone measurements are crucial to direct appropriate treatment. This study investigated the discrepant interpretation that often exists between urologic surgeons and radiologists' estimation of patient urinary stone burden. MATERIALS AND METHODS: From November 2015 through August 2016, new patients prospectively enrolled into the Registry for Stones of the Kidney and Ureter (ReSKU) were included if they had computed tomography images available and an accompanying official radiologic report at the time of their urologist provider visit. Stone number and aggregate stone size were compared between the urologic interpretation and the corresponding radiologic reports. RESULTS: Of 219 patients who met the inclusion criteria, concordance between urologic and radiologic assessment of aggregate stone size was higher for single stone sizing (63%) compared with multiple stones (32%). Statistical significance was found in comparing the mean difference in aggregate stone size for single and multiple stones (P <.01). Over 33% of stone-containing renal units had a radiologic report with an unclear size estimation or size discrepancy that could lead to non-guideline-driven surgical management. CONCLUSION: Significant variation exists between urologic and radiologic computed tomography interpretations of stone burden. Urologists should personally review patient imaging when considering stone surgical management. A standardized method for measuring and reporting stone parameters is needed among urologists and radiologists.

Prostate cancer in renal transplant recipients

ABSTRACT As patients with end-stage renal disease are receiving renal allografts at older ages, the number of male renal transplant recipients (RTRs) being diagnosed with prostate cancer (CaP) is increasing. Historically, the literature regarding the management of CaP in RTR's is limited to case reports and small case series. To date, there are no standardized guidelines for screening or management of CaP in these complex patients. To better understand the unique characteristics of CaP in the renal transplant population, we performed a literature review of PubMed, without date limitations, using a combination of search terms including prostate cancer, end stage renal disease, renal transplantation, prostate cancer screening, prostate specific antigen kinetics, immuno-suppression, prostatectomy, and radiation therapy. Of special note, teams facilitating the care of these complex patients must carefully and meticulously consider the altered anatomy for surgical and radiotherapeutic planning. Active surveillance, though gaining popularity in the general low risk prostate cancer population, needs further study in this group, as does the management of advance disease. This review provides a comprehensive and contemporary understanding of the incidence, screening measures, risk stratification, and treatment options for CaP in RTRs.

Optimizing RNA Extraction of Renal Papilla Biopsy Tissue in Kidney Stone Formers: A New Methodology for Genomic Study.

INTRODUCTION: Endoscopic tools have provided versatile examination and treatment for kidney stone procedures. Despite endourologists researching urinary stone disease using endoscopes to collect tissue, this tissue collection method is limited. Endoscopically removed tissues are small in size, restricting the types of genome-based examination possible. We investigated a new method of renal papilla biopsy and RNA extraction to establish a genomic research methodology for kidney stone disease. PATIENTS AND METHODS: We conducted a prospective multi-institutional study and collected renal papilla specimens from consecutive percutaneous nephrolithotomy and ureteroscopy (URS) cases performed for removal of upper urinary tract stones. Renal papilla tissue was extracted using ureteroscopic biopsy forceps after stone removal. RNA was extracted using two different extraction kits, and their quantity and quality were examined. Additionally, the impact of biopsy on surgical complications was compared between cases performed with and without biopsy by matched case-control analysis adjusted for age, gender, body mass index, bilaterality, and stone burden. RESULTS: A total of 90 biopsies from 49 patients were performed, and the median duration between specimen collection and RNA extraction was 61 days. Both univariate and multivariate analyses showed BIGopsy® forceps usage significantly increased the total yield (p = 0.004) and quality (p = 0.001 for A260/280, p = 0.004 for A260/A230) of extracted RNA. Extraction using the RNeasy Micro Kit® also improved A260/A230, whereas reduced RNA integrity number of extracted RNA by univariate and multivariate analyses (p = 0.002 and p < 0.001, respectively). Moreover, matched case-control study demonstrated that endoscopic renal papilla biopsy caused no significant surgical complications, including bleeding, decreased stone clearance and hematocrit, and renal dysfunction. Biopsies during URS imparted an average of 20 minutes of procedure time over nonbiopsy cases. CONCLUSIONS: We demonstrate a safe methodology for optimal RNA extraction of renal papilla tissue. This technique will accelerate advanced genomic studies for kidney stone formers by facilitating larger tissue yields.

En Bloc Stapling of the Renal Hilum During Laparoscopic Nephrectomy: A Double-institutional Analysis of Safety and Efficacy.

OBJECTIVE: To explore the safety and efficacy of en bloc stapling of the renal hilum (EBSH) during laparoscopic nephrectomy (LNx) in a large double-institution cohort with an extended follow-up period. METHODS: We performed a retrospective review of patients undergoing LNx with EBSH between 2008 and 2014 at 2 academic medical centers. Data analyzed included tumor size, tumor pathology, operative time, estimated blood loss, and perioperative or postoperative complications. Evaluation of arteriovenous fistula (AVF) formation was assessed by postoperative imaging studies, physical examination, or new-onset diastolic hypertension. RESULTS: A total of 428 patients (mean age: 63 years) underwent LNx, of which there were a total of 433 renal units with EBSH (226 left renal units, 207 right renal units). Mean operative time was 169 minutes (range: 51-489 minutes). Mean estimated blood loss was 155 mL (range: 5 mL-2000 mL). Mean tumor size was 5.6 cm (range: 0.9-14.5 cm). EBSH was performed on 69 patients with chronic infectious and inflammatory benign conditions. Three hundred (70%) patients received post-procedural imaging. No patients developed clinical or radiographic evidence of AVF at a mean follow-up of 51 months. CONCLUSION: EBSH during LNx is efficient, effective, and safe. This large series lends further support that EBSH during LNx may not be associated with any significant risk of AVF formation at extended follow-up. We advocate that this technique is a safe alternative to ligating the renal artery and vein during LNx.

Prostate cancer in renal transplant recipients.

As patients with end-stage renal disease are receiving renal allografts at older ages, the number of male renal transplant recipients (RTRs) being diagnosed with prostate cancer (CaP) is increasing. Historically, the literature regarding the management of CaP in RTR's is limited to case reports and small case series. To date, there are no standardized guidelines for screening or management of CaP in these complex patients. To better understand the unique characteristics of CaP in the renal transplant population, we performed a literature review of PubMed, without date limitations, using a combination of search terms including prostate cancer, end stage renal disease, renal transplantation, prostate cancer screening, prostate specific antigen kinetics, immunosuppression, prostatectomy, and radiation therapy. Of special note, teams facilitating the care of these complex patients must carefully and meticulously consider the altered anatomy for surgical and radiotherapeutic planning. Active surveillance, though gaining popularity in the general low risk prostate cancer population, needs further study in this group, as does the management of advance disease. This review provides a comprehensive and contemporary understanding of the incidence, screening measures, risk stratification, and treatment options for CaP in RTRs.

A Prospective Case-Control Study Comparing LithoVue, a Single-Use, Flexible Disposable Ureteroscope, with Flexible, Reusable Fiber-Optic Ureteroscopes.

OBJECTIVE: LithoVue™ is a novel, single-use, digital flexible ureteroscope that was released to the US market in January 2016. There are scant data regarding its performance in humans. Procedural outcomes comparing LithoVue with reusable ureteroscopes are presented in patients undergoing ureteroscopy for upper urinary tract pathology. PATIENTS AND METHODS: Clinical outcomes between two groups of patients undergoing flexible ureteroscopy for upper urinary tract pathology were analyzed. The first group underwent surgery utilizing LithoVue, and the second group used reusable fiber-optic flexible ureteroscopes. Differences in procedural outcomes, operative times, and time spent in hospital were analyzed using two-tailed t-tests and chi-squared and Fisher's exact tests. RESULTS: One hundred fifteen cases utilizing LithoVue and 65 cases utilizing reusable ureteroscopes were included in this study. Demographics, surgical indications, stone size, location, total stone burden, composition, procedural outcomes, and complications were comparable between groups. For all cases, LithoVue procedures lasted 54.1 ± 25.7 minutes compared with 64.5 ± 37.0 minutes for reusable scope procedures (p < 0.05) and for stone removal cases, 57.3 ± 25.1 vs 70.3 ± 36.9 minutes, respectively (p < 0.05). Scope failure occurred in 4.4% of LithoVue cases and 7.7% of reusable cases (p = 0.27). CONCLUSIONS: LithoVue represents a feasible alternative to reusable ureteroscopes with a low rate of scope failure comparable with reusable ureteroscopes. Its use shortens procedure duration, a finding that warrants further investigation.

Ecthyma gangrenosum of the scrotum: a case report.

A 43-year-old man with pancytopenia from chemotherapy for acute myeloid leukemia developed left scrotal pain, fever, and rigors. Physical exam revealed an ulcerating lesion with central necrosis and eschar surrounded by a halo of erythema on the inferior aspect of the left scrotum. The condition indicated an early necrotizing soft tissue infection. The patient was started on broad-spectrum antibiotics and taken to the operating room for a wound debridement. Blood and tissue cultures grew Pseudomonas aeruginosa, which confirmed the diagnosis of ecthyma gangrenosum of the scrotum. The fever resolved, and the wound healed without further progression after wet to dry dressing changes.

Contemporary Review of Treatment Options for Peyronie's Disease.

Peyronie's disease (PD) is a penile wound-healing disorder resulting in fibrotic plaque in the tunica albuginea, likely resulting from micro trauma. Due to variable disease presentations, a myriad of proposed treatment options, physician misconceptions about the disorder, and severe psychological distress in afflicted patients, PD can be a difficult to manage entity. This review seeks to provide a current and comprehensive overview of oral, topical, intralesional, mechanical, and surgical therapies for PD.

Urological Malpractice: Claim Trend Analysis and Severity of Injury.

INTRODUCTION: In the current malpractice environment all urologists are at risk. Claim trend data on costs, types of urological errors and severity of injury in urological surgery malpractice claims are lacking. METHODS: We analyzed physician level claim data from a large professional liability insurer with a nationwide client base. Available data included records on closed malpractice claims from 1985 to 2013. We evaluated insured demographics, total number of closed claims, costs of indemnity payments, costs of defense, types of errors resulting in closed claims and severity of injury in urological claims. RESULTS: Compared to other medical specialties urology ranks 13th in total claims and 15th in average cost of indemnity payments in the last decade. Most urological claims are dropped, dismissed or withdrawn without indemnity payment. Of closed urological claims 27.2% result in an indemnity payment to the plaintiff. Adjusting for inflation, urological indemnity payments have increased by 60% since the 1980s and average payouts are now greater than $350,000. Improper performance of a procedure is the most prevalent urological error resulting in closed claims (875 closed claims in the last decade). Procedures involving the kidney (245 closed claims) and prostate (244 closed claims) are most frequently implicated. The majority of urological errors result in temporary or minor permanent injury. Errors resulting in grave injury are the most costly, with average indemnity payments of $514,844. CONCLUSIONS: Awareness of claim trends and errors implicated can help urologists better understand the current malpractice environment.

Visual Internal Urethrotomy With Intralesional Mitomycin C and Short-term Clean Intermittent Catheterization for the Management of Recurrent Urethral Strictures and Bladder Neck Contractures.

OBJECTIVE: To evaluate our longitudinal experience using visual internal urethrotomy (VIU) with intralesional mitomycin C (MMC) and short-term clean intermittent catheterization (CIC) for urethral strictures and bladder neck contractures (BNC) after failure of endoscopic management. MATERIALS AND METHODS: This case series involved review of our prospectively developed database of all men who underwent VIU with MMC and CIC in a standardized fashion for urethral stricture or BNC between 2010 and 2013 at our tertiary care medical center. Etiology was identified as radiation-induced stricture (RIS) or non-RIS and analyzed by stricture location. Cold knife incisions were made in a tri or quadrant fashion followed by intralesional injection of MMC and 1 month of once daily CIC. RESULTS: All 37 patients previously underwent at least 1 intervention for urethral stricture or BNC before VIU with MMC and CIC. Mean stricture length was 2.0 cm (range, 1-6 cm; standard deviation, 1.0 cm). Over the median follow-up period of 23 months (range, 12-39 months), 75.7% of patients required no additional surgical intervention (RIS, 54.5%; non-RIS, 84.6%; P = .051). In those that did recur, median time to stricture recurrence was 8 months (range, 2-28 months). One patient with recurrence required urethroplasty. CONCLUSION: VIU with MMC followed by short-term CIC provides a minimally invasive and widely available tool to manage complex recurrent urethral strictures (<3 cm) and BNC without significant morbidity. This approach may be most attractive for patients who are poor candidates for open surgery.

Pharmacologic therapy for Peyronie's disease: what should we prescribe?

INTRODUCTION: Peyronie's disease (PD) is a wound healing disorder of the penis with a myriad of proposed treatment options reported in the literature. Evaluating the available data and therapeutic management of PD can be challenging and confusing, even for the most experienced treating physician. This review provides a comprehensive overview of pharmacologic treatment options for PD, focusing on the best available evidence. AREAS COVERED: A comprehensive literature search for published articles evaluating oral, topical, and injectable pharmacologic agents for PD was completed. Prospective, controlled trials were given precedence for inclusion. EXPERT OPINION: Although a multitude of oral agents have been proposed and evaluated in PD patients, results vary widely and a reproducible objective benefit has not yet been strongly established for any single oral agent. Well-designed, large-scale, randomized controlled trials evaluating oral agents in PD patients are lacking. Consistent objective benefit from injectable agents has been supported for years by various non-controlled trials. Recently, injectable collagenase Clostridium histolyticum became the first pharmacologic agent to obtain FDA approval for use in PD patients, supported by data from a large-scale, Phase III randomized controlled trial. Further elucidation of the genetic and mechanistic pathways involved in the development and progression of PD will help define future therapeutic targets.

The Current State of Medical Malpractice in Urology.

Medical malpractice can present an unwelcome professional, emotional, and economic burden to the practicing urologist. To date, there is a paucity of data specific to urologic malpractice in the literature. We performed a comprehensive literature search to identify and evaluate recent studies related to urologic malpractice. We also analyzed 6249 closed urologic claims from the largest available specialty-specific data set gathered by Physician Insurers Association of America from 1985 to 2012. The resulting comprehensive review seeks to raise awareness of current trends in the malpractice environment specific to urologic surgery while also helping urologists identify opportunities for risk management and improved patient care.

2013-2014 updates in Peyronie's disease management.

The number of patients presenting with Peyronie's disease (PD) appears to be on the rise. This review provides an analysis of pertinent recent updates in the management of PD, focusing on data published within the past year. Objective benefit from injectable agents has been reported for years in mostly noncontrolled trials. The safety and efficacy of injectable collagenase clostridium histolyticum is now supported by data from a large-scale phase III randomized controlled trial. Other important advances have also been made in the surgical management of Peyronie's disease, including new modifications to proven surgical techniques and a variety of approaches that can help enhance and restore penile length.

Current management of erectile dysfunction in prostate cancer survivors.

PURPOSE OF REVIEW: Although no standard management of erectile dysfunction in prostate cancer (CaP) survivors exists, many treatment options are available. This review summarizes the current understanding of the cause and management of erectile dysfunction in CaP survivors. RECENT FINDINGS: Erectile dysfunction after radical therapy for CaP may be more common than previously thought. Genetics and vascular comorbidities may have a significant impact on erectile dysfunction after CaP treatment. Although penile rehabilitation with medical modalities show good efficacy in motivated patients, the return of erectile function is never guaranteed with nonsurgical management. Penile prosthesis placement results in early return to sexual function after CaP treatment with high patient satisfaction rates. Various techniques allow safe placement of a three-piece penile prosthesis in patients with a history of pelvic surgery. SUMMARY: To optimize recovery of erectile function and prevent loss of penile length, penile rehabilitation should be initiated expeditiously after prostatectomy or radiation. In patients with refractory erectile dysfunction, dexterous and motivated patients remain excellent candidates for first and second-line medical therapies. However, early placement of a penile prosthesis following radical prostatectomy is now a proven and viable option.

Hypofractionated stereotactic body radiation therapy as monotherapy for intermediate-risk prostate cancer.

BACKGROUND: Hypofractionated stereotactic body radiation therapy (SBRT) has been advanced as monotherapy for low-risk prostate cancer. We examined the dose distributions and early clinical outcomes using this modality for the treatment of intermediate-risk prostate cancer. METHODS: Forty-one sequential hormone-naïve intermediate-risk prostate cancer patients received 35-36.25 Gy of CyberKnife-delivered SBRT in 5 fractions. Radiation dose distributions were analyzed for coverage of potential microscopic ECE by measuring the distance from the prostatic capsule to the 33 Gy isodose line. PSA levels, toxicities, and quality of life (QOL) measures were assessed at baseline and follow-up. RESULTS: All patients completed treatment with a mean coverage by the 33 Gy isodose line extending >5 mm beyond the prostatic capsule in all directions except posteriorly. Clinical responses were documented by a mean PSA decrease from 7.67 ng/mL pretreatment to 0.64 ng/mL at the median follow-up of 21 months. Forty patients remain free from biochemical progression. No Grade 3 or 4 toxicities were observed. Mean EPIC urinary irritation/obstruction and bowel QOL scores exhibited a transient decline post-treatment with a subsequent return to baseline. No significant change in sexual QOL was observed. CONCLUSIONS: In this intermediate-risk patient population, an adequate radiation dose was delivered to areas of expected microscopic ECE in the majority of patients. Although prospective studies are needed to confirm long-term tumor control and toxicity, the short-term PSA response, biochemical relapse-free survival rate, and QOL in this interim analysis are comparable to results reported for prostate brachytherapy or external beam radiotherapy. TRIAL REGISTRATION: The Georgetown Institutional Review Board has approved this retrospective study (IRB 2009-510).

Low incidence of new biochemical and clinical hypogonadism following hypofractionated stereotactic body radiation therapy (SBRT) monotherapy for low- to intermediate-risk prostate cancer.

BACKGROUND: The CyberKnife is an appealing delivery system for hypofractionated stereotactic body radiation therapy (SBRT) because of its ability to deliver highly conformal radiation therapy to moving targets. This conformity is achieved via 100s of non-coplanar radiation beams, which could potentially increase transitory testicular irradiation and result in post-therapy hypogonadism. We report on our early experience with CyberKnife SBRT for low- to intermediate-risk prostate cancer patients and assess the rate of inducing biochemical and clinical hypogonadism. METHODS: Twenty-six patients were treated with hypofractionated SBRT to a dose of 36.25 Gy in 5 fractions. All patients had histologically confirmed low- to intermediate-risk prostate adenocarcinoma (clinical stage ≤ T2b, Gleason score ≤ 7, PSA ≤ 20 ng/ml). PSA and total testosterone levels were obtained pre-treatment, 1 month post-treatment and every 3 months thereafter, for 1 year. Biochemical hypogonadism was defined as a total serum testosterone level below 8 nmol/L. Urinary and gastrointestinal toxicity was assessed using Common Toxicity Criteria v3; quality of life was assessed using the American Urological Association Symptom Score, Sexual Health Inventory for Men and Expanded Prostate Cancer Index Composite questionnaires. RESULTS: All 26 patients completed the treatment with a median 15 months (range, 13-19 months) follow-up. Median pre-treatment PSA was 5.75 ng/ml (range, 2.3-10.3 ng/ml), and a decrease to a median of 0.7 ng/ml (range, 0.2-1.8 ng/ml) was observed by one year post-treatment. The median pre-treatment total serum testosterone level was 13.81 nmol/L (range, 5.55 - 39.87 nmol/L). Post-treatment testosterone levels slowly decreased with the median value at one year follow-up of 10.53 nmol/L, significantly lower than the pre-treatment value (p < 0.013). The median absolute fall was 3.28 nmol/L and the median percent fall was 23.75%. There was no increase in biochemical hypogonadism at one year post-treatment. Average EPIC sexual and hormonal scores were not significantly changed by one year post-treatment. CONCLUSIONS: Hypofractionated SBRT offers the radiobiological benefit of a large fraction size and is well-tolerated by men with low- to intermediate-risk prostate cancer. Early results are encouraging with an excellent biochemical response. The rate of new biochemical and clinical hypogonadism was low one year after treatment.