Urethral strictures following high-dose-rate brachytherapy for prostate cancer: analysis of risk factors

169Yb-based high dose rate intensity modulated brachytherapy for focal treatment of prostate cancer

PURPOSE

This study compares conventional 192Ir-based high dose rate brachytherapy (HDR-BT) with 169Yb-based HDR intensity modulated brachytherapy (IMBT) for focal prostate cancer treatment. Additionally, the study explores the potential to generate less invasive treatment plans with IMBT by reducing the number of catheters needed to achieve acceptable outcomes.

METHODS AND MATERIALS

A retrospective dosimetric study of ten prostate cancer patients initially treated with conventional 192Ir-based HDR-BT and 5-14 catheters was employed. RapidBrachyMCTPS, a Monte Carlo-based treatment planning system was used to calculate and optimize dose distributions. For 169Yb-based HDR IMBT, a custom 169Yb source combined with 0.8 mm thick platinum shields placed inside 6F catheters was used. Furthermore, dose distributions were investigated when iteratively removing catheters for less invasive treatments.

RESULTS

With IMBT, the urethra D10 and D0.1cc decreased on average by 15.89 and 15.65 percentage points (pp) and the rectum V75 and D2cc by 1.53 and 11.54 pp, respectively, compared to the conventional clinical plans. Similar trends were observed when the number of catheters decreased. On average, there was an observed increase in PTV V150 from 2.84 pp with IMBT when utilizing all catheters to 8.83 pp when four catheters were removed. PTV V200 increased from 0.42 to 2.96 pp on average. Hotspots in the body were however lower with IMBT compared to conventional clinical plans.

CONCLUSIONS

169Yb-based HDR IMBT for focal treatment of prostate cancer has the potential to successfully deliver clinically acceptable, less invasive treatment with reduced dose to organs at risk.

Urinary Organs at Risk for Prostate Cancer External Beam Radiation Therapy: Contouring Guidelines on Behalf of the Francophone Group of Urological Radiation Therapy

PURPOSE

The occurrence of genitourinary (GU) toxicity is a common adverse event observed after external beam radiation therapy (EBRT) for prostate cancer (PCa). Recent findings suggest that the dose delivered to specific urinary organs at risk (OARs) such as the ureters, bladder trigone, and urethra is involved in the development of GU toxicity.

METHODS AND MATERIALS

A multidisciplinary task force including 3 radiation oncologists, a uroradiologist, and a urologist was created in 2022. First, OARs potentially involved in GU toxicity were identified and discussed. A literature review was performed, addressing several questions relative to urinary OARs: anatomic and radiological definition, radiation-induced injury, and dose-volume parameters. Second, results were presented and discussed with a panel of radiation oncologists and members of the "Francophone Group of Urological Radiation Therapy." Thereafter, the "Francophone Group of Urological Radiation Therapy" experts were asked to answer a dedicated questionnaire, including 35 questions on the controversial issues related to the delineation of urinary OARs.

RESULTS

The following structures were identified as critical for PCa EBRT: ureters, bladder, bladder neck, bladder trigone, urethra (intraprostatic, membranous, and spongious), striated sphincter, and postenucleation or posttransurethral resection of the prostate cavity. A consensus was obtained for 32 out of 35 items.

CONCLUSIONS

This consensus highlights contemporary urinary structures in both the upper and lower urinary tract to be considered for EBRT treatment planning of PCa. The current recommendations also propose a standardized definition of urinary OARs for both daily practice and future clinical trials.

Management of the Devastated Bladder Outlet after Prostate CANCER Treatment

PURPOSE OF REVIEW

Devastating complications of the bladder outlet resulting from prostate cancer treatments are relatively uncommon. However, the combination of the high incidence of prostate cancer and patient longevity after treatment have raised awareness of adverse outcomes deteriorating patients' quality of life. This narrative review discusses the diagnostic work-up and management options for bladder outlet obstruction resulting from prostate cancer treatments, including those that require urinary diversion.

RECENT FINDINGS

The devastated bladder outlet can be a consequence of the treatment of benign conditions, but more frequently from complications of pelvic cancer treatments. Regardless of etiology, the initial treatment ladder involves endoluminal options such as dilation and direct vision internal urethrotomy, with or without intralesional injection of anti-fibrotic agents. If these conservative strategies fail, surgical reconstruction should be considered. Although surgical reconstruction provides the best prospect of durable success, reconstructive procedures are also associated with serious complications. In the worst circumstances, such as prior radiotherapy, failed reconstruction, devastated bladder outlet with end-stage bladders, or patient's severe comorbidities, reconstruction may neither be realistic nor justified. Urinary diversion with or without cystectomy may be the best option for these patients. Thorough patient counseling before treatment selection is of utmost importance. Outcomes and repercussions on quality of life vary extensively with management options. Meticulous preoperative diagnostic evaluation is paramount in selecting the right treatment strategy for each individual patient. The risk of bladder outlet obstruction, and its severest form, devastated bladder outlet, after treatment of prostate cancer is not negligible, especially following radiation. Management includes endoluminal treatment, open or robot-assisted laparoscopic reconstruction, and urinary diversion in the worst circumstances, with varying success rates.

State of the art and future challenges of urethra-sparing stereotactic body radiotherapy for prostate cancer: a systematic review of literature

PURPOSE

Doses delivered to the urethra have been associated with an increased risk to develop long-term urinary toxicity in patients undergoing stereotactic body radiotherapy (SBRT) for prostate cancer (PCa). Aim of the present systematic review is to report on the role of urethra-sparing SBRT (US-SBRT) techniques for prostate cancer, with a focus on outcome and urinary toxicity.

METHOD

A systematic review of the literature was performed on the PubMed database on May 2023. Based on the urethra-sparing technique, 13 studies were selected for the analysis and classified in the two following categories: "urethra-steering" SBRT (restriction of hotspots to the urethra) and "urethra dose-reduction" SBRT (dose reduction to urethra below the prescribed dose).

RESULTS

By limiting the urethra Dmax to 90GyEQD2 (α/β = 3 Gy) with urethra-steering SBRT techniques, late genitourinary (GU) grade 2 toxicity remains mild, ranging between 12.1% and 14%. With dose-reduction strategies decreasing the urethral dose below 70 GyEQD2, the risk of late GU toxicity was further reduced (< 8% at 5 years), while maintaining biochemical relapse-free survival rates up to 93% at 5 years.

CONCLUSION

US-SBRT techniques limiting maximum doses to urethra below a 90GyEQD2 (α/β = 3 Gy) threshold result in a low rate of acute and late grade ≥ 2 GU toxicity. A better understanding of clinical factors and anatomical substructures involved in the development of GU toxicity, as well as the development and use of adapted dose constraints, is expected to further reduce the long-term GU toxicity of prostate cancer patients treated with SBRT.

A novel direction modulated brachytherapy technique for urethra sparing in high-dose-rate brachytherapy of prostate cancer

PURPOSE

Image-guided high-dose-rate (HDR) prostate brachytherapy is a safe and effective treatment option for prostate cancer patients; however, some patients still experience acute and late genitourinary (GU) toxicity. Studies have shown that urethral dose is associated with the incidence and severity of GU toxicity. Therefore, a technique that can further spare the urethra while ensuring adequate target coverage is highly desirable. Intensity modulated brachytherapy (IMBT) designs, such as rotating shield brachytherapy (RSBT), offer ideal dosimetry theoretically but are challenging to implement clinically due to the need for high precision in moving the treatment delivery mechanisms synchronized with the source loading. In this study, we propose a novel relatively easy-to-implement solution based on the direction modulated brachytherapy (DMBT) design concept, which does not involve moving parts and works effectively with the ubiquitous 192Ir source.

MATERIALS AND METHODS

The popular Varian VS2000 (VS) and GammaMedPlus (GMP) 192Ir sources, with outer diameters of 0.6 mm and 0.9 mm, respectively, were simulated using the GEANT4 Monte Carlo (MC) simulation code. The novel DMBT needle concept consists of a 14-gauge nitinol needle, which houses a platinum shield inside. A single groove, consistent with the outer diameter of each source, was incorporated inside the platinum shield to accommodate the HDR source. The maximum thickness of the shield was 1.1 mm (0.8 mm) for the VS (GMP) source. To evaluate the effectiveness of the DMBT needle concept in reducing urethral dose, 6 patient cases were studied and DMBT plans were created by replacing two needles close to the urethra with the DMBT needles. The dosimetric comparisons between the DMBT and reference clinical plans were done by assessing the dose-volume histogram (DVH) planning criteria for the target coverage and organs-at-risk.

RESULTS

The MC results showed that the use of the novel DMBT needle design with the VS source (GMP source) could reduce the dose by 49.6% (39.2%) at 1 cm from the needle behind the platinum shield, as compared to the unshielded side. Additionally, when using the same DVH planning criteria as the original plan, the DMBT plan with the VS (GMP) source reduced the maximum urethral dose by 10.3% ± 5.6% (8.1% ± 5.0%) and 17.7% ± 14.2% (16.6% ± 13.3%) for 0 mm and 2 mm margins, respectively, while maintaining equivalent V90% and D100 target coverage.

CONCLUSION

The novel DMBT technique offers a promising clinically implementable solution for sparing urethra, particularly in pre-apical region, without compromising the target coverage or increasing treatment time.

Complications after Prostate Cancer Treatment: Pathophysiology and Repair of Post-Radiation Urethral Stricture Disease

Radiation therapy (RT) in the management of pelvic cancers remains a clinical challenge to urologists given the sequelae of urethral stricture disease secondary to fibrosis and vascular insults. The objective of this review is to understand the physiology of radiation-induced stricture disease and to educate urologists in clinical practice regarding future prospective options clinicians have to deal with this condition. The management of post-radiation urethral stricture consists of conservative, endoscopic, and primary reconstructive options. Endoscopic approaches remain an option, but with limited long-term success. Despite concerns with graft take, reconstructive options such as urethroplasties in this population with buccal grafts have shown long-term success rates ranging from 70 to 100%. Robotic reconstruction is augmenting previous options with faster recovery times. Radiation-induced stricture disease is challenging with multiple interventions available, but with successful outcomes demonstrated in various cohorts including urethroplasties with buccal grafts and robotic reconstruction.

Comparison of outcomes in high-risk prostate cancer patients treated with low-/high-dose-rate brachytherapy plus external beam radiotherapy

BACKGROUND

Although brachytherapy is a standard treatment option for patients with high-risk prostate cancer, only a few studies have compared low-dose-rate brachytherapy (LDR-BT) and high-dose-rate brachytherapy (HDR-BT). We applied propensity score-based inverse probability treatment weighting (IPTW) to compare oncological outcomes for LDR-BT and HDR-BT.

METHODS

We retrospectively assessed prognosis in 392 patients with high-risk localized prostate cancer who had undergone brachytherapy plus external beam radiation. IPTW was applied to adjust the Kaplan-Meier survival analyses and Cox proportional hazards regression analyses, with the goal of minimizing bias from patient background.

RESULTS

The IPTW-adjusted Kaplan-Meier survival analyses showed no statistically significant differences for time to biochemical recurrence, clinical progression, castration-resistant prostate cancer, or death from any cause. The IPTW-adjusted Cox regression analyses also showed that the modality of brachytherapy was not an independent factor in these oncological outcomes. Notably, the two groups differed regarding complications; LDR-BT was associated with a higher rate of acute grade ≥ 2 GU toxicity, and late grade 3 toxicity was noted only in HDR-BT.

CONCLUSION

Our analysis of long-term outcomes in patients with high-risk localized prostate cancer shows no significant differences in oncological outcomes between LDR-BT and HDR-BT, but some differences in toxicity, and offers patients and clinicians useful information in deciding management strategies for high-risk localized prostate cancer.

A multimodality review of male urethral imaging: pearls and pitfalls with an update on urethral stricture treatment

Optimum radiological assessment of the male urethra requires knowledge of the normal urethral anatomy and ideal imaging techniques based on the specific clinical scenario. Retrograde urethrography is the workhorse examination for male urethral imaging, usually utilized as the initial, and often solitary, modality of choice not only in the setting of trauma, but also in the pre- and post-operative evaluation of urethral strictures. There is, however, growing interest in utilization of ultrasound and magnetic resonance for evaluation of the male urethra owing to lack of ionizing radiation and improved delineation of the adjacent tissue. We review the various modalities utilized for imaging of the male urethra for a variety of known or suspected disorders, and provide an update on current treatments of urethral strictures. Additionally, we detail the key information needed by urologists to guide management of urethral strictures. We conclude with a brief discussion of neophallus urethral diseases following female-to-male sexual confirmation surgery.

Long-Term Experience with Balloon Dilation for Short Bulbar and Membranous Urethral Strictures: Establishing a Baseline in the Active Drug Treatment Era

Transurethral balloon dilation (BD) is a minimally invasive treatment for urethral stricture disease (USD) performed primarily or as a recurrence salvage maneuver. With the introduction of drug-coated balloons, we sought to characterize patient outcomes using non-medicated balloons. A retrospective review identified patients who underwent BD from 2007 to 2021. Patient and stricture characteristics were collected. All dilations employed the 24Fr UroMaxTM system. Clinical failure was defined by patient-reported lower urinary tract symptom recurrence or need for further stricture management. Ninety-one patients underwent BD with follow-up median (IQR) 12 (3–40) months. Most (75/91, 82%) had prior treatment for USD (endoscopic 50/91 (55%), 51/91 (56%) urethroplasty) before BD. Recurrence rates did not significantly differ between treatment-naïve and salvage patients (44% vs. 52% (p = 0.55)). Median (IQR) time to failure was 6 (3–13) months. The most common complications were urinary tract infection (8%) and post-operative urinary retention requiring catheterization (3%). Radiation history was noted in 33/91 (36%) with 45% recurrence. Patients without previous radiation had a similar recurrence rate of 52% (p = 0.88). Balloon dilation had minimal complications and overall, 50% recurrence rate, consistent regardless of stricture characteristics, radiation history, or prior treatments. These results represent an important clinical benchmark for comparing outcomes using drug-coated balloons.

Stereotactic Radiation Therapy versus Brachytherapy: Relative Strengths of Two Highly Efficient Options for the Treatment of Localized Prostate Cancer

Stereotactic body radiation therapy (SBRT) has become a valid option for the treatment of low- and intermediate-risk prostate cancer. In randomized trials, it was found not inferior to conventionally fractionated external beam radiation therapy (EBRT). It also compares favorably to brachytherapy (BT) even if level 1 evidence is lacking. However, BT remains a strong competitor, especially for young patients, as series with 10-15 years of median follow-up have proven its efficacy over time. SBRT will thus have to confirm its effectiveness over the long-term as well. SBRT has the advantage over BT of less acute urinary toxicity and, more hypothetically, less sexual impairment. Data are limited regarding SBRT for high-risk disease while BT, as a boost after EBRT, has demonstrated superiority against EBRT alone in randomized trials. However, patients should be informed of significant urinary toxicity. SBRT is under investigation in strategies of treatment intensification such as combination of EBRT plus SBRT boost or focal dose escalation to the tumor site within the prostate. Our goal was to examine respective levels of evidence of SBRT and BT for the treatment of localized prostate cancer in terms of oncologic outcomes, toxicity and quality of life, and to discuss strategies of treatment intensification.

Devastated Bladder Outlet in Pelvic Cancer Survivors: Issues on Surgical Reconstruction and Quality of Life

Bladder outlet obstruction following treatment of pelvic cancer, predominantly prostate cancer, occurs in 1-8% of patients. The high incidence of prostate cancer combined with the long-life expectancy after treatment has increased concerns with cancer survivorship care. However, despite increased oncological cure rates, these adverse events do occur, compromising patients' quality of life. Non-traumatic obstruction of the posterior urethra and bladder neck include membranous and prostatic urethral stenosis and bladder neck stenosis (also known as contracture). The devastated bladder outlet can result from benign conditions, such as neurogenic dysfunction, trauma, iatrogenic causes, or more frequently from complications of oncologic treatment, such as prostate, bladder and rectum. Most posterior urethral stenoses may respond to endoluminal treatments such as dilatation, direct vision internal urethrotomy, and occasionally urethral stents. Although surgical reconstruction offers the best chance of durable success, these reconstructive options are fraught with severe complications and, therefore, are far from being ideal. In patients with prior RT, failed reconstruction, densely fibrotic and/or necrotic and calcified posterior urethra, refractory incontinence or severe comorbidities, reconstruction may not be either feasible or recommended. In these cases, urinary diversion with or without cystectomy is usually required. This review aims to discuss the diagnostic evaluation and treatment options for patients with bladder outlet obstruction with a special emphasis on patients unsuitable for reconstruction of the posterior urethra and requiring urinary diversion.

Reduction of toxicity in brachytherapy using a new technique

PURPOSE

The purpose of the study was to elucidate the usefulness of a dose evaluation method for reducing late genitourinary (GU) toxicity in high-dose-rate brachytherapy (HDR-BT) of prostate cancer.

METHODS AND MATERIALS

GU toxicity was scored in accordance with the Common Terminology Criteria for Adverse Events version 4.0. The prostatic urethra was divided into three segments (base = B, midgland = M, apex = A), which were subclassified into seven subgroups (B, M, A, BM, BA, MA, BMA) using a D_10% color map of the urethra. Significance testing was conducted on urethral D_0.1% and D_10% among the seven subgroups. Grade < 2 GU toxicity was also implemented.

RESULTS

Data of 174 patients with localized prostate cancer treated with HDR-BT combined with external beam radiotherapy between November 2011 and July 2014 were analyzed retrospectively. Median age was 74 (53-84) years, and median followup period was 44 (6-69) months. The number of Grade < 2 and Grade ≥ 2 toxicity was significantly different in the M subgroup than in the other subgroups (p < 0.05), suggesting increased radioresistance in the midgland urethra.

CONCLUSIONS

A high-dose-area evaluation method using a urethral D_10% color map may be helpful in reducing late GU toxicity in HDR-BT for prostate cancer.

Current Management of Membranous Urethral Strictures Due to Radiation

Radiotherapy is a frequently used treatment for prostate cancer. It does not only causes the intended damage to cancer cells, but also affects healthy surrounding tissue. As a result radiation-induced urethral strictures occur in 2.2% of prostate cancer patients. Management of urethral strictures is challenging due to the presence of poor vascularized tissue for reconstruction and the proximity of the sphincter, which can impair the functional outcome. This review provides a literature overview of risk factors, diagnostics and management of radiation-induced urethral strictures.

HDR brachytherapy boost using MR-only workflow for intermediate- and high-risk prostate cancer: 8-year results of a pilot study

PURPOSE

To report 8-year clinical outcome with high-dose-rate brachytherapy (HDRBT) boost using MRI-only workflow for intermediate (IR) and high-risk (HR) prostate cancer (PC) patients.

METHODS AND MATERIALS

Fifty-two patients were treated with 46-60 Gy of 3D conformal radiotherapy preceded and/or followed by a single dose of 8-10 Gy MRI-guided HDRBT. Interventions were performed in a 0.35 T MRI scanner. Trajectory planning, navigation, contouring, catheter reconstruction, and dose calculation were exclusively based on MRI images. Biochemical relapse-free- (BRFS), local relapse-free- (LRFS), distant metastasis-free- (DMFS), cancer-specific-(CCS) and overall survival (OS) were analyzed. Late morbidity was scored using the Common Terminology Criteria for Adverse Events (CTCAE 4.0) combined with RTOG (Radiation Therapy Oncology Group) scale for urinary toxicity and rectal urgency (RU) determined by Yeoh.

RESULTS

Median follow-up time was 107 (range: 19-143) months. The 8-year actuarial rates of BRFS, LRFS, DMFS, CSS and OS were 85.7%, 97%, 97.6%, and 77.6%, respectively. There were no Gr.3 GI side effects. The 8-year actuarial rate of Gr.2 proctitis was 4%. The 8-year cumulative incidence of Gr.3 GU side effects was 8%, including two urinary stenoses (5%) and one cystitis (3%). EPIC urinary and bowel scores did not change significantly over time.

CONCLUSIONS

MRI-only HDR-BT boost with moderate dose escalation provides excellent 8-year disease control with a favorable toxicity profile for IRPC and HRPC patients. Our results support the clinical importance of MRI across the BT workflow.

Risk factors for urethral stricture following external beam radiotherapy and HDR brachytherapy for prostate cancer

PURPOSE

A potential late side effect of high-dose-rate (HDR) prostate brachytherapy combined with external beam radiotherapy (EBRT) is urethral stricture. The purpose of this study was to evaluate dosimetric parameters possibly contributing to stricture development, including dose to bladder base and D2cc(Gy) within 10 mm of prostatic urethra (D2cc _10 mm), which has, so far, not been reported in the literature.

METHODS AND MATERIALS

Patients developing urethral stricture, and matched controls, were identified from a prospective database of those receiving 46 Gy in 23 fractions of EBRT, followed by a single 15 Gy HDR brachytherapy dose. Patients had locally advanced, high- and intermediate-risk prostate cancer. Brachytherapy treatment planning parameters (planning target volume (PTV) size (cm ³), V110(%) _{bladder base}, D2cc _10mm, number of HDR catheters, number of source dwell positions, and total source dwell time within 10 mm of the prostatic urethra) were analyzed to determine potential risk factors for urethral stricture.

RESULTS

Seventy-two patients were treated, 22 of whom developed a urethral stricture. Univariate logistic regression performed on the planning parameters identified increased PTV size and D2cc _10 mm, with decreased V110(%) _{bladder base} as risk factors for stricture formation.

CONCLUSIONS

It is suggested that PTV size, V110(%) _{bladder base}, and D2cc _10mm are predictive of urethral stricture formation following EBRT and brachytherapy to the prostate. This study demonstrates the importance of minimizing high dwell times and hot spots close to organs at risk and also the correction of any craniocaudal movement of catheters to avoid potential hot spots in the bulbomembranous urethra where there may be increased dose sensitivity.

169 Yb-based rotating shield brachytherapy for prostate cancer

PURPOSE

To present a system for the treatment of prostate cancer in a single-fraction regimen using ¹⁶⁹ Yb-based rotating shield brachytherapy (RSBT) with a single-catheter robotic delivery system. The proposed system is innovative because it can deliver RSBT through multiple implanted needles independently, in serial, using flexible catheters, with no inter-needle shielding effects and without the need to rotate multiple shielded catheters inside the needles simultaneously, resulting in a simple, mechanically robust, delivery approach. RSBT was compared to conventional ¹⁹² Ir-based high-dose-rate brachytherapy (HDR-BT) in a treatment planning study with dose escalation and urethral sparing goals, representing single-fraction brachytherapy monotherapy and brachytherapy as a boost to external beam radiotherapy, respectively. A prototype mechanical delivery system was constructed and quantitatively evaluated as a proof of concept.

METHODS

Treatment plans for twenty-six patients with single fraction prescriptions of 20.5 and 15 Gy, were created for dose escalation and urethral sparing, respectively. The RSBT and HDR-BT delivery systems were modeled with one partially shielded 999 GBq (27 Ci) ¹⁶⁹ Yb source and one 370 GBq (10 Ci) ¹⁹² Ir source, respectively. A prototype angular drive system for helical source delivery was constructed. Mechanical accuracy measurements of source translational position and angular orientation in a simulated treatment delivery setup were obtained using the prototype system.

RESULTS

For dose escalation, with equivalent urethra D_10% , PTV D_90% for RSBT vs HDR-BT increased from 22.6 ± 0.0 Gy (average ± standard deviation) to 29.3 ± 0.9 Gy, or 29.9 % ± 3.0%, with treatment times of 51.4 ± 6.1 min for RSBT and 15.8 ± 2.3 min for 10 Ci ¹⁹² Ir-based HDR-BT. For urethra sparing, with equivalent PTV D_{90 %} , urethra D_10% for RSBT vs HDR-BT decreased for RSBT vs HDR-BT from 15.6 ± 0.4 Gy to 12.0 ± 0.4 Gy, or 23.1% ± 3.5%, with treatment times of 30.0 ± 3.7 min for RSBT and 12.3 ± 1.8 min for HDR-BT. Differences between measured vs predicted rotating catheter positions (corresponding to source position) were within 0.18 mm ± 0.12 mm longitudinally and 0.07° ± 0.78°.

CONCLUSION

¹⁶⁹ Yb-based RSBT can increase PTV D_90% or decrease urethral D_10% relative to HDR-BT with treatment times of less than 1 h using a single-source robotic delivery system with treatment delivered in a single fraction. The prototype helical delivery system was able to demonstrate adequate mechanical accuracy.

Canadian Urological Association guideline on male urethral stricture

Urethral stricture is fundamentally a fibrosis of the urethral epithelial and associated corpus spongiosum, which in turn, causes obstruction of the urethral lumen. Patients with urethral stricture most commonly present with lower urinary tract symptoms, urinary retention or urinary tract infection but may also experience a broad spectrum of other signs and symptoms, including genitourinary pain, hematuria, abscess, ejaculatory dysfunction, or renal failure. When urethral stricture is initially suspected based on clinical assessment, cystoscopy is suggested as the modality that most accurately establishes the diagnosis. This recommendation is based on several factors, including the accuracy of cystoscopy, as well as its wide availability, lesser overall cost, and comfort of urologists with this technique. When recurrent urethral stricture is suspected, we suggest performing retrograde urethrography to further stage the length and location of the stricture or referring the patient to a physician with expertise in reconstructive urology. Ultimately, the treatment decision depends on several factors, including the type and acuity of patient symptoms, the presence of complications, prior interventions, and the overall impact of the urethral stricture on the patient's quality of life. Endoscopic treatment, either as dilation or internal urethrotomy, is suggested rather than urethroplasty for the initial treatment of urethral stricture. This recommendation applies to men with undifferentiated urethral stricture and does not apply to trauma-related urethral injuries, penile urethral strictures (hypospadias, lichen sclerosus), or suspected urethral malignancy. In the setting of recurrent urethral stricture, urethroplasty is suggested rather than repeat endoscopic management but this may vary depending on patient preference and impact of the symptoms on the patient.The purpose of this guideline is to provide a practical summary outlining the diagnosis and treatment of urethral stricture in the Canadian setting.

External Validation of a Predictive Model of Urethral Strictures for Prostate Patients Treated With HDR Brachytherapy Boost

Purpose: For prostate cancer treatment, comparable or superior biochemical control was reported when using External-Beam-Radiotherapy (EBRT) with High-Dose-Rate-Brachytherapy (HDRB)-boost, compared to dose-escalation with EBRT alone. The conformal doses produced by HDRB could allow further beneficial prostate dose-escalation, but increase in dose is limited by normal tissue toxicity. Previous works showed correlation between urethral dose and incidence of urinary toxicity, but there is a lack of established guidelines on the dose constraints to this organ. This work aimed at fitting a Normal-Tissue-Complication-Probability model to urethral stricture data collected at one institution and validating it with an external cohort, looking at neo-adjuvant androgen deprivation as dose-modifying factor.

Materials and Methods: Clinical and dosimetric data of 258 patients, with a toxicity rate of 12.8%, treated at a single institution with a variety of prescription doses, were collected to fit the Lyman–Kutcher–Burman (LKB) model using the maximum likelihood method. Due to the different fractionations, doses were converted into 2 Gy-equivalent doses (α/β = 5 Gy), and urethral stricture was used as an end-point. For validation, an external cohort of 187 patients treated as part of the TROG (Trans Tasman Radiation Oncology Group) 03.04 RADAR trial with a toxicity rate of 8.7%, was used. The goodness of fit was assessed using calibration plots. The effect of neo-adjuvant androgen deprivation (AD) was analyzed separating patients who had received it prior to treatment from those who did not receive it.

Results: The obtained LKB parameters were TD50 = 116.7 Gy and m = 0.23; n was fixed to 0.3, based on numerical optimization of the likelihood. The calibration plot showed a good agreement between the observed toxicity and the probability predicted by the model, confirmed by bootstrapping. For the external validation, the calibration plot showed that the observed toxicity obtained with the RADAR patients was well-represented by the fitted LKB model parameters. When patients were stratified by the use of AD TD50 decreased when AD was not present.

Conclusions: Lyman–Kutcher–Burman model parameters were fitted to the risk of urethral stricture and externally validated with an independent cohort, to provide guidance on urethral tolerance doses for patients treated with a HDRB boost. For patients that did not receive AD, model fitting provided a lower TD50 suggesting a protective effect on urethra toxicity.

A pilot study on dosimetric and radiomics analysis of urethral strictures following HDR brachytherapy as monotherapy for localized prostate cancer

OBJECTIVE

A cohort of high dose-rate (HDR) monotherapy patients was analyzed to (i) establish the frequency of non-malignant urethral stricture; (ii) explore the relation between stricture formation with the dose distribution along the length of the urethra, and MRI radiomics features of the prostate gland.

METHODS

A retrospective review of treatment records of patients who received 19 Gy single fraction of HDR brachytherapy (BT) was carried out. A matched pair analysis used one control for each stricture case matched with pre-treatment International Prostate Symptom Score (IPSS) score, number of needles used and clinical target volume volume for each stricture case identified.For all data sets, pre-treatment T₂ weighted MRI images were used to define regions of interests along the urethra and within the whole prostate gland. MRI textural radiomics features-energy, contrast and homogeneity were selected. Wilcoxon signed-rank test was performed to investigate significant differences in dosimetric parameters and MRI radiomics feature values between cases and controls.

RESULTS

From Nov 2010 to July 2017, there were 178 patients treated with HDR BT delivering 19 Gy in a single dose. With a median follow-up of 28.2 months, a total of 5/178 (3%) strictures were identified.10 patients were included in the matched pair analysis. The urethral dosimetric parameters investigated were not statistically different between cases and controls (p > 0.05). With regards to MRI radiomics feature analysis, significant differences were found in contrast and homogeneity between cases and controls (p < 0.05). However, this did not apply to the energy feature (p = 0.28).

CONCLUSION

In this matched pair analysis, no association between post-treatment stricture and urethral dosimetry was identified. Our study generated a preliminary clinical hypothesis suggesting that the MRI radiomics features of homogeneity and contrast of the prostate gland can potentially identify patients who develop strictures after HDR BT. Although the sample size is small, this warrants further validation in a larger patient cohort.

ADVANCES IN KNOWLEDGE

Urethral stricture has been reported as a specific late effect with prostate HDR brachytherapy. Our study reported a relatively low stricture rate of 3% and no association between post-treatment stricture and urethral dosimetry was identified. MRI radiomics features can potentially identify patients who are more prone to develop strictures.

Multiparametric MRI-guided dose boost to dominant intraprostatic lesions in CT-based High-dose-rate prostate brachytherapy

OBJECTIVE

The purpose of this study is to investigate the dosimetric feasibility of delivering focal dose to multiparametric (mp) MRI-defined DILs in CT-based high-dose-rate (HDR) prostate brachytherapy with MR/CT registration and estimate its clinical benefit.

METHODS

We retrospectively investigated a total of 17 patients with mp-MRI and CT images acquired pre-treatment and treated by HDR prostate brachytherapy. 21 dominant intraprostatic lesions (DILs) were contoured on mp-MRI and propagated to CT images using a deformable image registration method. A boost plan was created for each patient and optimized on the original needle pattern. In addition, separate plans were generated using a virtually implanted needle around the DIL to mimic mp-MRI guided needle placement. DIL dose coverage and organ-at-rick (OAR) sparing were compared with original plan results. Tumor control probability (TCP) was estimated to further evaluate the clinical impact on the boost plans.

RESULTS

Overall, optimized boost plans significantly escalated dose to DILs while meeting OAR constraints. The addition of mp-MRI guided virtual needles facilitate increased coverage of DIL volumes, achieving a V150 > 90% in 85 % of DILs compared with 57 % of boost plan without an additional needle. Compared with original plan, TCP models estimated improvement in DIL control by 28 % for patients with external-beam treatment and by 8 % for monotherapy patients.

CONCLUSION

With MR/CT registration, the proposed mp-MRI guided DIL boost in CT-based HDR brachytherapy is feasible without violating OAR constraints, and indicates significant clinical benefit in improving TCP of DIL. It may represent a strategy to personalize treatment delivery and improve tumor control.

ADVANCES IN KNOWLEDGE

This study investigated the feasibility of mp-MRI guided DIL boost in HDR prostate brachytherapy with CT-based treatment planning, and estimated its clinical impact by TCP and NTCP estimation.

Pelvic Complications After Prostate Cancer Radiation Therapy and Their Management: An International Collaborative Narrative Review

CONTEXT

Radiotherapy used for treating localized prostate cancer is effective at prolonging cancer-specific and overall survival. Still, acute and late pelvic toxicities are a concern, with gastrointestinal (GI) and genitourinary (GU) sequelae being most common as well as other pelvic complications.

OBJECTIVE

To present a critical review of the literature regarding the incidence and risk factors of pelvic toxicity following primary radiotherapy for prostate cancer and to provide a narrative review regarding its management.

EVIDENCE ACQUISITION

A collaborative narrative review of the literature from 2010 to present was conducted.

EVIDENCE SYNTHESIS

Regardless of the modality used, the incidence of acute high-grade pelvic toxicity is low following conventionally fractionated external beam radiotherapy (EBRT). After moderate hypofractionation, the crude cumulative incidences for late grade 3 or higher (G3+) GI and GU complications are as high as 6% and 7%, respectively. After extreme hypofractionation, the 5-yr incidences of G2+ GU and GI toxicities are 3-9% and 0-4%, respectively. Following brachytherapy monotherapy, crude rates of late G3+ GU toxicity range from 6% to 8%, while late GI toxicity is rare. With combination therapy (EBRT and brachytherapy), the cumulative incidence of late GU toxicity is high, between 18% and 31%; however, the prevalence is lower at 4-14%. Whole pelvic radiotherapy remains a controversial treatment option as there is increased G3+ GI toxicity compared with prostate-only treatment, with no overall survival benefit. Proton beam therapy appears to have similar toxicity to photon therapies currently in use. With respect to specific complications, urinary obstruction and urethral stricture are the most common severe urinary toxicities. Rectal and urinary bleeding can be recurrent long-term toxicities. The risk of hip fracture is also increased following prostate radiotherapy. The literature is mixed on the risk of in-field secondary pelvic malignancies following prostate radiotherapy. Urinary and GI fistulas are rare complications. Management of these toxicities may require invasive treatment and reconstructive surgery for refractory and severe symptoms.

CONCLUSIONS

There has been progress in the delivery of radiotherapy, enabling the administration of higher doses with minimal tradeoff in terms of slightly increased or equal toxicity. There is a need to focus future improvements in radiotherapy on sparing critical structures to reduce GU and GI morbidities. While complications such as fistulae, bone toxicity, and secondary malignancy are rare, there is a need for higher-quality studies assessing these outcomes and their management.

PATIENT SUMMARY

In this report, we review the literature regarding pelvic complications following modern primary prostate cancer radiotherapy and their management. Modern radiotherapy technologies have enabled the administration of higher doses with minimal increases in toxicity. Overall, high-grade long-term toxicity following prostate radiotherapy is uncommon. Management of late high-grade pelvic toxicities can be challenging, with patients often requiring invasive therapies for refractory cases.

A Systematic Post-QUANTEC Review of Tolerance Doses for Late Toxicity After Prostate Cancer Radiation Therapy

PURPOSE

The aims of this study were to systematically review tolerance doses for late distinct gastrointestinal (GI), genitourinary (GU), and sexual dysfunction (SD) symptoms after external beam radiation therapy (EBRT) alone and treatments involving brachytherapy (BT) for prostate cancer after Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) and ultimately to perform quantitative syntheses of identified dose/volume tolerances represented by dose-volume histogram (DVH) thresholds, that is, statistically significant (P ≤ .05) cutoff points between symptomatic and asymptomatic patients in a certain study.

METHODS AND MATERIALS

PubMed was scrutinized for full-text articles in English after QUANTEC (January 1, 2010). The inclusion criteria were randomized controlled trials, case-control studies, or cohort studies with tolerance doses for late distinct symptoms ≥3 months after primary radiation therapy for prostate cancer (N > 30). All DVH thresholds were converted into equivalent doses in 2-Gy fractions (EQD2α/β) and were fitted with a linear or linear-quadratic function (goodness of fit, R2). The review was registered on PROSPERO (CRD42016042464).

RESULTS

From 33 identified studies, which included 36 to 746 patients per symptom domain, the majority of dose/volume tolerances were derived for GI toxicity after EBRT alone (GI, 97 thresholds; GU, 8 thresholds; SD, 1 threshold). For 5 symptoms (defecation urgency, diarrhea, fecal incontinence, proctitis, and rectal bleeding), relationships between dose/volume tolerances across studies (R2 = 0.93 [0.82-1.00]), and across symptoms, leading to a curve for overall GI toxicity (R2 = 0.98), could be determined. For these symptoms, mainly rectal thresholds were found throughout low and high doses (10 Gy ≤ equivalent dose in 2-Gy fractions using α/β = 3Gy (EQD23) ≤ 50 Gy and 55 Gy ≤ EQD23 ≤ 78 Gy, respectively). For BT with or without EBRT, dose/volume tolerances were also mainly identified for GI toxicity (GI, 14 thresholds; GU, 4 thresholds; SD, 2 thresholds) with the largest number of DVH thresholds concerning rectal bleeding (5 thresholds).

CONCLUSIONS

Updated dose/volume tolerances after QUANTEC were found for 17 GI, GU, or SD symptoms. A DVH curve described the relationship between dose/volume tolerances across 5 GI symptoms after EBRT alone. Restricting treatments for EBRT alone using the lower boundaries of this curve is likely to limit overall GI toxicity, but this should be explored prospectively. Dose/volume tolerances for GU and SD toxicity after EBRT alone and after BT with or without EBRT were scarce and support further research including data-sharing initiatives to untangle the dose/volume relationships for these symptoms.

A case-control study using motion-inclusive spatial dose-volume metrics to account for genito-urinary toxicity following high-precision radiotherapy for prostate cancer

Background and purpose

Material and methods

Results

Conclusions

Management of Urethral Stricture and Bladder Neck Contracture Following Primary and Salvage Treatment of Prostate Cancer

PURPOSE OF REVIEW

This article discusses the incidence, evaluation, and treatment of bladder outlet obstruction from urethral stricture, vesicourethral anastomotic stricture, and bladder neck contracture following primary and salvage treatment of prostate cancer.

RECENT FINDINGS

Rates of stenosis after prostate cancer treatment appear similar across all primary treatment modalities including radical prostatectomy, radiation therapy, cryoablation, and high-intensity focused ultrasound in contemporary series. Urethral dilation and urethrotomy continue to report moderate patency rates. Urethroplasty achieves high patency rates even for long strictures, but more extensive reconstruction increases the risk of postoperative urinary incontinence. Recent AUA guidelines on urethral strictures provide new recommendations for management of these patients. All treatment options for prostate cancer carry a risk for bladder outlet obstruction, and intervention is often necessary to relieve long-lasting morbidity. Careful preoperative evaluation should be completed to assess location and extent of the stricture in order to choose optimal therapy. Endoscopic treatments, open reconstruction, and urinary diversion all play a role in relief of stenosis depending on stricture length, location, characteristics, and patient comorbidities.

Under-utilisation of high-dose-rate brachytherapy boost in men with intermediate-high risk prostate cancer treated with external beam radiotherapy

INTRODUCTION

The aim of this study was to evaluate the use of high-dose-rate brachytherapy (HDR-BT) boost with definitive external beam radiotherapy (EBRT) in prostate cancer (CaP) management.

METHODS

The study population comprised men with intermediate-high risk CaP captured in the population-based Prostate Cancer Outcome Registry Victoria (PCOR-Vic), treated with EBRT from January 2010 to December 2015. The primary outcome is the proportion of men who received HDR-BT boost. Multivariate logistic regressions were used to evaluate the effect of patient-, tumour- and treatment-factors on the likelihood of HDR-BT use. Medicare Benefit Schedule (MBS) data was accessed to evaluate the Australia-wide pattern of HDR-BT use.

RESULTS

One thousand eight hundred and six patients were included in this study - 886 (49%) intermediate-risk, and 920 (51%) high-risk CaP patients. Overall, only 124 (7%) patients had EBRT + HDR-BT - 47 (5%) intermediate-risk and 77 (8%) high-risk CaP patients (P = 0.01). There is higher proportion of patients who had HDR-BT in public institutions (7% public vs. 3% private, P = 0.005) and in metropolitan centres (9% metropolitan vs. 2% regional, P < 0.001). In multivariate analyses, older patients were less likely to have HDR-BT (OR = 0.92; 95% CI = 0.89-0.94, P < 0.001), while patients with high-risk CaP (OR = 1.8; 95% CI = 1.3-2.7; P = 0.002) treated in metropolitan centres (OR = 5.0; 95% CI = 2.6-9.8; P < 0.001) and public institutions (OR = 3.8; 95% CI = 1.5-9.4; P = 0.005) were more likely to have EBRT + HDR-BT. There was significant decline in numbers of HDR-BT performed throughout Australia, from 313 cases in 2010 to 125 cases in 2015.

CONCLUSION

High-dose-rate brachytherapy is under-utilised with EBRT in this contemporary population-based cohort of Victorian men with CaP. The decline in HDR-BT use was also observed nationally.

Does supplemental external beam radiation therapy impact urinary, bowel, and erectile function following permanent prostate brachytherapy?: results of two prospective randomized trials

Purpose

To evaluate the impact of supplemental external beam radiation therapy (EBRT) prior to permanent prostate brachytherapy on long term urinary, bowel, and erectile function.

Material and methods

Patient administered urinary, bowel, and erectile quality of life (QoL) instrument were obtained prior to treatment and following brachytherapy. The study population was comprised of the 457 patients who were alive as of June 2016, had been randomized to two markedly different supplemental EBRT dose regimens and a third arm without supplemental EBRT, and had completed the June 2016 QoL survey. The need for urinary or bowel surgical intervention was prospectively recorded during routine follow-up. Multiple parameters were evaluated for effect on outcomes.

Results

The urinary catheter was removed on day 0 in 92.1% of patients and 0.4% required a post-implant transurethral prostatic resection (TURP). On average, the International Prostate Symptom Score (IPSS) normalized at week 14. The 10-year rate of urethral strictures was 5.3%. No significant differences were discerned between baseline and post-implant rectal function assessment score (RFAS), and no patient developed a rectal ulcer or fistula. The 10-year potency preservation rate was 50.3%. Supplemental EBRT did not affect urinary, bowel, or erectile function. Urethral strictures were most closely related to bulbomembranous urethral brachytherapy doses, post-implant rectal function to pre-implant hemorroidal bleeding, and RFAS and erectile function to pre-brachytherapy international index of erectile function and age.

Conclusions

Supplemental EBRT did not significantly effect catheter dependency, IPSS resolution, urethral stricture rate, the need for post-implant TURP, bowel, or erectile function. Careful attention to brachytherapy dose distributions appears to be most important in minimizing post-brachytherapy morbidity.

Multisource Rotating Shield Brachytherapy Apparatus for Prostate Cancer

PURPOSE

Our purpose is to present a novel multisource rotating shield brachytherapy (RSBT) apparatus for the simultaneous precise angular and linear positioning of partially shielded ¹⁵³Gd brachytherapy sources in interstitial needles for the treatment of locally advanced prostate cancer. It is designed to lower the dose to nearby healthy tissues, the urethra in particular, relative to conventional high-dose-rate brachytherapy techniques.

METHODS AND MATERIALS

Following needle implantation through the patient template, an angular drive mechanism is docked to the patient template. Each needle is coupled to a multisource afterloader catheter by a connector passing through a shaft. The shafts are rotated about their axes by translating a moving template between 2 stationary templates. The shafts' surfaces and moving template holes are helically threaded with the same pattern such that translation of the moving template causes simultaneous rotation of the shafts. The rotation of each shaft is mechanically transmitted to the catheter-source-shield combination, inside the needles, via several key-keyway pairs. The catheter angles are simultaneously incremented throughout treatment, and only a single 360° rotation of all catheters is needed for a full treatment. For each rotation angle, source depth in each needle is controlled by a multisource afterloader, which is proposed as an array of belt-driven linear actuators, each of which drives a wire that controls catheter depth in a needle.

RESULTS

Treatment plans demonstrated that RSBT with the proposed apparatus reduced urethral D_0.1cm³ (the minimum dose delivered to the hottest 0.1cm³ of the urethra) below that of conventional high-dose-rate brachytherapy by 31% for urethral dose gradient volume within 3 mm of the urethra surface. Treatment time to deliver 20 Gy with the proposed multisource RSBT apparatus by use of nineteen 62.4-GBq ¹⁵³Gd sources was 122 minutes.

CONCLUSIONS

The proposed RSBT delivery apparatus enables a mechanically feasible urethra-sparing treatment technique for prostate cancer in a clinically reasonable time frame.

Management of bladder neck stenosis and urethral stricture and stenosis following treatment for prostate cancer

The aim of this review is to examine all urethral strictures and stenoses subsequent to treatment for prostate cancer, including radical prostatectomy (RP), radiotherapy, high intensity focused ultrasound (HIFU) and cryotherapy. The overall majority respond to endoscopic treatment, including dilatation, direct visual internal urethrotomy (DVIU) or bladder neck incision (BNI). There are adjunct treatments to endoscopic management, including injections of corticosteroids and mitomycin C (MMC) and urethral stents, which remain controversial and are not currently mainstay of treatment. Recalcitrant strictures are most commonly managed with urethroplasty, while recalcitrant stenosis is relatively rare yet almost always associated with bothersome urinary incontinence, requiring bladder neck reconstruction and subsequent artificial urinary sphincter (AUS) implantation, or urinary diversion for the devastated outlet.

Treatment of Radiation-Induced Urethral Strictures

Radiation therapy may result in urethral strictures from vascular damage. Most radiation-induced urethral strictures occur in the bulbomembranous junction, and urinary incontinence may result as a consequence of treatment. Radiation therapy may compromise reconstruction due to poor tissue healing and radionecrosis. Excision and primary anastomosis is the preferred urethroplasty technique for radiation-induced urethral stricture. Principles of posterior urethroplasty for trauma may be applied to the treatment of radiation-induced urethral strictures. Chronic management with suprapubic tube is an option based on patient comorbidities and preference.

[Urethral stricture rate after prostate cancer radiotherapy : Five-year data of a certified prostate cancer center]

BACKGROUND

A urethral stricture is a scar of the urethral epithelium which can cause obstructive voiding dysfunction with consequential damage of the upper urinary tract. Almost 45% of all strictures are iatrogenic; they develop in 2-9% of patients after radical prostatectomy, but can also occur after prostate cancer radiotherapy. This study provides 5‑year data of a certified prostate cancer center (PKZ) in terms of urethral strictures.

MATERIALS AND METHODS

Between 01/2008 and 12/2012 a total of 519 men were irradiated for prostate cancer (LDR and HDR brachytherapy as well as external beam radiation). The entire cohort was followed-up prospectively according to a standardized protocol (by type of irradiation). Short segment urethral strictures were treated by urethrotomy, recurrent and long segment stenosis with buccal mucosa urethroplasty.

RESULTS

A total of 18 of 519 (3.4%) patients developed a urethral stricture post-therapeutically, which recurred in 66% of cases after the first operative treatment. The largest risk for developing a urethral stricture is attributed to the HDR brachytherapy (8.9%).

CONCLUSION

Urethral strictures after prostate cancer radiotherapy should be diagnosed and treated in time for long-term preservation of renal function. The rate of radiogenic urethral strictures (3.4%) is equivalent to those after radical prostatectomy. Due to a high rate of recurrences, urethrotomy has a limited importance after irradiation.

Nontraumatic posterior urethral stenosis

INTRODUCTION

Posterior urethral stenoses and contractures are complications after treatment of benign prostatic hyperplasia (BPH), localised prostate cancer (PCa), and orthotopic neobladder formation, compromising prognosis and functional outcomes.

OBJECTIVES

To identify factors related to aetiology, prevention and treatment of non-traumatic posterior urethral stenosis and contractures.

ACQUISITION OF EVIDENCE

Review of the published evidence related to posterior urethral stenosis and contractures after PCa treatment, BPH therapies and orthotopic neobladder formation. PubMed database search with English and Spanish papers considered. Cohort studies, case series, prospective and retrospective studies and review papers were included.

SYNTHESIS OF EVIDENCE

Posterior urethral stenoses and contractures are common, leading to significant morbidity. A worsening on voiding quality should rise some concerns. Careful surgical and/or radiotherapic techniques prevent their development. Endoscopic therapies are the initial approach, with complex urethroplasties often required. Subsequent urinary incontinence, the most important sequelae, may need artificial sphincters.

CONCLUSIONS

Non-traumatic posterior urethral stenoses could be important complications, potentially compromising the outcomes of initial therapy. They could require complex surgeries leading to urinary incontinence.

Magnetic resonance imaging-guided functional anatomy approach to prostate brachytherapy

PURPOSE

To provide an MRI based functional anatomy guide to prostate brachytherapy.

METHODS AND MATERIALS

We performed a narrative review of periprostatic functional anatomy and the significance of this anatomy in prostate brachytherapy treatment planning.

RESULTS

MRI has improved delineation of gross tumor and critical periprostatic structures that have been implicated in toxicity. Furthermore, MRI has revealed the significant anatomic variants and the dynamic nature of these structures that can have significant implications for treatment planning and dosimetry.

CONCLUSIONS

The MRI-based functional anatomy approach to prostate brachytherapy takes into account extent of disease, its relation to the patient's individual anatomy, and functional baseline to optimize the therapeutic ratio of prostate cancer treatment.

American Brachytherapy Society Task Group Report: Combination of brachytherapy and external beam radiation for high-risk prostate cancer

PURPOSE

To review outcomes for high-risk prostate cancer treated with combined modality radiation therapy (CMRT) utilizing external beam radiation therapy (EBRT) with a brachytherapy boost.

METHODS AND MATERIALS

The available literature for high-risk prostate cancer treated with combined modality radiation therapy was reviewed and summarized.

RESULTS

At this time, the literature suggests that the majority of high-risk cancers are curable with multimodal treatment. Several large retrospective studies and three prospective randomized trials comparing CMRT to dose-escalated EBRT have demonstrated superior biochemical control with CMRT. Longer followup of the randomized trials will be required to determine if this will translate to a benefit in metastasis-free survival, disease-specific survival, and overall survival. Although greater toxicity has been associated with CMRT compared to EBRT, recent studies suggest that technological advances that allow better definition and sparing of critical adjacent structures as well as increasing experience with brachytherapy have improved implant quality and the toxicity profile of brachytherapy. The role of androgen deprivation therapy is well established in the external beam literature for high-risk disease, but there is controversy regarding the applicability of these data in the setting of dose escalation. At this time, there is not sufficient evidence for the omission of androgen deprivation therapy with dose escalation in this population. Comparisons with surgery remain limited by differences in patient selection, but the evidence would suggest better disease control with CMRT compared to surgery alone.

CONCLUSIONS

Due to a series of technological advances, modern combination series have demonstrated unparalleled rates of disease control in the high-risk population. Given the evidence from recent randomized trials, combination therapy may become the standard of care for high-risk cancers.

Urethral strictures after radiation therapy for prostate cancer

Urethral stricture after radiation therapy for localized prostate cancer is a delicate problem as the decreased availability of tissue healing and the close relation to the sphincter complicates any surgical approach. We here review the pathophysiology, dosimetry, and the disease specific aspects of urethral strictures after radiotherapy. Moreover we discuss different treatment option such as direct vision internal urethrotomy as well as techniques for open reconstruction with and without tissue transfer.

Urethroplasty in radiation-induced strictures

PURPOSE OF REVIEW

In patients presenting with urethral stricture disease, the mainstay of definitive treatment is urethroplasty. Until recently, it was unclear if urethroplasty was a feasible option in patients with urethral stricture secondary to pelvic radiation exposure. We review the feasibility and outcomes for urethroplasty in patients with radiation-induced urethral stricture.

RECENT FINDINGS

Urethroplasty in patients exposed to radiation can be technically challenging secondary to stricture location and tissue damage; however, it still has an acceptable success rate with durable outcomes. Most radiation-induced strictures are limited in length, located in the bulbomembranous region, and are amenable to excision and primary anastomosis. There are higher rates of postoperative urinary incontinence in this cohort when compared with outcomes for urethroplasty without radiation exposure; however, erectile function appears to be preserved.

SUMMARY

Recent studies highlight that urethroplasty has acceptable success rates in men with radiation-induced urethral stricture. Patients in this cohort need to be counseled on the potential for urinary incontinence following urethroplasty.

Obstructive urination problems after high-dose-rate brachytherapy boost treatment for prostate cancer are avoidable

Background

Aiming at improving treatment individualization in patients with prostate cancer treated with combination of external beam radiotherapy and high-dose-rate brachytherapy to boost the dose to prostate (HDRB-B), the objective was to evaluate factors that have potential impact on obstructive urination problems (OUP) after HDRB-B.

Patients and methods

In the follow-up study 88 patients consecutively treated with HDRB-B at the Institute of Oncology Ljubljana in the period 2006-2011 were included. The observed outcome was deterioration of OUP (DOUP) during the follow-up period longer than 1 year. Univariate and multivariate relationship analysis between DOUP and potential risk factors (treatment factors, patients’ characteristics) was carried out by using binary logistic regression. ROC curve was constructed on predicted values and the area under the curve (AUC) calculated to assess the performance of the multivariate model.

Results

Analysis was carried out on 71 patients who completed 3 years of follow-up. DOUP was noted in 13/71 (18.3%) of them. The results of multivariate analysis showed statistically significant relationship between DOUP and anti-coagulation treatment (OR 4.86, 95% C.I. limits: 1.21-19.61, p = 0.026). Also minimal dose received by 90% of the urethra volume was close to statistical significance (OR = 1.23; 95% C.I. limits: 0.98-1.07, p = 0.099). The value of AUC was 0.755.

Conclusions

The study emphasized the relationship between DOUP and anticoagulation treatment, and suggested the multivariate model with fair predictive performance. This model potentially enables a reduction of DOUP after HDRB-B. It supports the belief that further research should be focused on urethral sphincter as a critical structure for OUP.

Management of radiation-induced urethral strictures

Radiation as a treatment option for prostate cancer has been chosen by many patients. One of the side effects encountered are radiation-induced urethral strictures which occur in up to 11% of patients. Radiation damage has often left the irradiated field fibrotic and with poor vascularization which make these strictures a challenging entity to treat. The mainstay of urologic management remains an urethroplasty procedure for which several approaches exist with variable optimal indication. Excision and primary anastomoses are ideal for shorter bulbar strictures that comprise the majority of radiation-induced urethral strictures. One advantage of this technique is that it does not require tissue transfers and success rates of 70-95% have consistently been reported. Substitution urethroplasty using remote graft tissue such as buccal mucosa are indicated if the length of the stricture precludes a tension-free primary anastomosis. Despite the challenge of graft survival in radiation-damaged and poorly vascularized recipient tissue, up to 83% of patients have been treated successfully although the numbers described in the literature are small. The most extensive repairs involve the use of tissue flaps, for example gracilis muscle, which may be required if the involved periurethral tissue is unable to provide sufficient vascular support for a post-operative urethral healing process. In summary, radiation-induced urethral strictures are a challenging entity. Most strictures are amenable to excision and primary anastomosis (EPA) with encouraging success rates but substitution urethroplasty may be indicated when extensive repair is needed.

High dose rate brachytherapy for prostate cancer: Standard of care and future direction

High dose rate brachytherapy is a highly conformal method of radiation dose escalation for prostate cancer and one of several treatment options for men with localised disease. The large doses per fraction exploit the low alpha/beta ratio of prostate cancer cells so that biological radiation dose delivered is substantially greater than that achieved with conventional external beam delivery. This review article presents contemporary data on the rationale for high dose rate brachytherapy including treatment technique and future directions.

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.