Surgical Treatments of Benign Prostatic Hyperplasia and Prostate Cancer Stereotactic Radiotherapy: Impact on Long-Term Genitourinary Toxicity

Urethra-sparing prostate cancer radiotherapy: Current practices and future insights from an international survey

Purpose

In prostate cancer patients, high radiation doses to the urethra have been associated with an increased risk of severe genitourinary toxicity following dose-escalated radiotherapy. Urethra-sparing techniques have emerged as a promising approach to reduce urinary toxicity. This international survey aims to evaluate current global practices in urethra-sparing and explore future directions for the implementation of this technique in external beam radiotherapy (EBRT) for prostate cancer.

Methods and materials

In April 2024, a survey consisting of 20 questions was distributed to 26 international radiation oncology experts in prostate cancer EBRT, with 23 experts participating. The survey focused on clinical scenarios which might take benefit from urethra-sparing, the definition of the urethra and urinary organs-at-risk, and urethral dose constraints.

Results

Magnetic resonance imaging with T2-weighted sequences is the preferred method for urethra contouring (83 % consensus). Based on the experts opinion, urethra-sparing should be considered for prostate cancer EBRT, regardless of pelvic irradiation, except in cases where the tumor is located within 2 mm of the urethra and/or transitional zone, or in T4 disease. Most experts would not apply specific dose constraints to the urethra for either conventional or moderate hypofractionation regimens. When delivering stereotactic body radiotherapy (SBRT), urethra-sparing with dose hotspot limitation (urethra steering) is recommended by 70 % of the experts, in particular when combined with focal boosting (91 %). Urethra dose-reduction is also the favored approach for salvage prostate reirradiation with SBRT (70 % agreement). Large variations exists regarding urethral dose constraints.

Conclusions

Urethra-sparing is a promising technique for the mitigation of urinary toxicity in prostate cancer patients undergoing EBRT, particularly recommended for ultra-hypofractionation and reirradiation with SBRT. The lack of consensus on specific urethral dose constraints and optimal sparing techniques underscores the need for further research to standardize practices in this field.

Late Urinary Toxicity After Extreme or Moderate Hypofractionated Prostate Radiation Therapy in Patients With Prior Transurethral Resection of Prostate

PURPOSE

To study the late urinary toxicity in patients with prostate cancer with prior transurethral resection of prostate (TURP) and treated with hypofractionated prostate radiation therapy.

METHODS AND MATERIALS

Patients diagnosed with prostate cancer, with a prior TURP, and treated with moderate or extreme hypofractionated intensity-modulated radiation therapy (moderate hypofractionated radiation therapy [MHRT], stereotactic body radiation therapy [SBRT]), were included in this study. Severity and duration of urinary symptoms observed during serial follow-up after at least 3 months from radiation therapy were graded per National Cancer Institute Common Terminology Criteria for Adverse Events v5.0 using information from a prospectively maintained institutional database. Impact of hypofractionation and other potential contributory factors on cumulative grade 2+ late urinary toxicity was analyzed with univariable and multivariable binary logistic regression.

RESULTS

A total of 203 eligible patients were included (MHRT = 114, 64-68 Gy/25#; SBRT = 89, 35-37.5 Gy/5#). Median time from TURP to radiation therapy was 10 months (IQR, 7-16 months), similar for MHRT and SBRT. Overall, mean cavity volume was 1.17 cc (IQR, 0.5-1.35 cc), whereas in MHRT and SBRT groups it was 1.03 cc (IQR, 0.4-1.15 cc) and 1.27 cc (IQR, 0.5-1.4 cc), respectively. At a median follow-up of 37 months, cumulative grade 3 and grade 2 late urinary toxicity was 8.4% (n = 17) and 23.2% (n = 47), respectively. Grade 3 symptoms were observed at median 29 months (IQR, 19-62 months) after radiation therapy completion, lasting for a median duration of 8 months (IQR, 2-14 months). Hematuria (6.4%) and urinary obstruction (3.4%) were the chief grade 3 symptoms. Multivariable analysis for age, diabetes, pelvic radiation therapy, fraction size, prostate volume, TURP to radiation therapy duration, and TURP cavity volume showed no significant association with late grade 2+ urinary toxicity.

CONCLUSIONS

In this large cohort of patients with prior TURP and treated with hypofractionated prostate radiation therapy, incidence of severe late urinary adverse effects was <10%, mainly hematuria or urinary obstruction. Most of these were temporary, and no significant contributory factors were identified for late urinary morbidity after TURP and radiation therapy.

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.

Genitourinary toxicity in patients receiving TURP prior to hypofractionated radiotherapy for clinically localized prostate cancer: A scoping review

BACKGROUND

When compared with conventional external beam radiotherapy, hypofractionated radiotherapy has led to less treatment sessions and improved quality of life without compromising oncological outcomes for men with prostate cancer. Evidence has shown transurethral prostatic resection prior to brachytherapy and external beam radiotherapy is associated with worsening genitourinary toxicity. However, there is no review of genitourinary toxicity when TURP occurs prior to definitive hypofractionated radiotherapy. In this review, we seek to illustrate the genitourinary outcomes for men with localized prostate cancer who underwent transurethral resection of the prostate prior to receiving definitive hypofractionated radiotherapy. Genitourinary outcomes are explored, and any predictive risk factors for increased genitourinary toxicity are described.

METHODS

PubMed, Medline (Ovid), EMBASE and Cochrane Library were all searched for relevant articles published in English within the last 25 years. This scoping review identified a total of 579 articles. Following screening by authors, 11 articles were included for analysis.

RESULTS

Five studies reported on acute and late toxicity. One article reported only acute toxicity while 5 documented late toxicity only. While most articles found no increased risk of acute toxicity, the risk of late toxicity, particularly hematuria was noted to be significant. Risk factors including poor baseline urinary function, prostate volume, number of prior transurethral prostatic resections, timing of radiotherapy following transurethral prostatic resection, volume of the intraprostatic resection cavity and mean dose delivered to the cavity were all found to influence genitourinary outcomes.

CONCLUSION

For those who have undergone prior TURP hypofractionated radiotherapy may increase the risk of late urinary toxicity, particularly hematuria. Those with persisting bladder dysfunction following TURP are at greatest risk and careful management of these men is required. Close collaboration between urologists and radiation oncologists is recommended to discuss the management of patients with residual baseline bladder dysfunction prior to commencing hypofractionated radiotherapy.

Extreme hypofractionated stereotactic radiotherapy for localized prostate Cancer: Efficacy and late urinary toxicity according to transurethral resection of the prostate history

Background and purpose

Extreme hypofractionated stereotactic body radiotherapy (SBRT) is a therapeutic alternative for localized low- or intermediate-risk prostate cancer. Despite the availability of several studies, the toxicity profile of SBRT has not been comprehensively described. This real-world evidence study assessed the efficacy and toxicities associated with this regimen, and potential prognosis factors for genitourinary toxicities.

Materials and methods

This retrospective study included 141 consecutive patients with localized prostatic adenocarcinoma treated with CyberKnife™ SBRT, as primary irradiation, at the Oscar Lambret Center between 2010 and 2020. The prescribed dose was 36.25 Gy in 5 fractions. Acute and late toxicities were graded according to the CTCAE (version 5.0). Biochemical recurrence-free survival (bRFS) and overall survival (OS) were estimated using the Kaplan-Meier method. The cumulative incidence of biochemical recurrence (cBR) was estimated using the Kalbfleisch-Prentice method.

Results

Among the included patients, 13.5 % had a history of transurethral resection of the prostate (TURP). The median follow-up was 48 months. At 5 years, bRFS, cBR, and OS were 72 % (95 %CI: 61-81), 7 % (95 %CI: 3-14), and 82 % (95 %CI: 73-89), respectively. Twenty-nine patients experienced at least one late toxicity of grade ≥ 2; genitourinary (N = 29), including 3 cases of chronic hematuria, and/or gastrointestinal (N = 1). The cumulative incidence of late urinary toxicity of grade ≥ 2 was 20.6 % at 5 years (95 %CI: 13.9-28.1). Multivariate analysis revealed that a history of TURP was significantly associated with late urinary toxicity of grade ≥ 2, after adjusting for clinical target volume (Odds Ratio = 3.06; 95%CI: 1.05-8.86; P = 0.04).

Conclusion

Extreme hypofractionated SBRT is effective for localized prostate cancer with a low risk of late toxicity. A history of TURP is associated with a higher risk of late urinary toxicity. These findings may contribute to the optimal management of patients treated with this regimen, particularly those with a history of TURP.

Stereotactic body radiation therapy for prostate cancer after surgical treatment of prostatic obstruction: Impact on urinary morbidity and mitigation strategies

In the past decade, stereotactic body radiation therapy (SBRT) has emerged as a valid treatment option for patients with localized prostate cancer. Despite the promising results of ultra-hypofractionation in terms of tolerance and disease control, the toxicity profile of SBRT for prostate cancer patients with a history of surgical treatment of benign prostate hyperplasia is still underreported. Here we present an overview of the available data on urinary morbidity for prostate cancer patients treated with SBRT after prior surgical treatments for benign prostate hyperplasia. Technical improvements useful to minimize toxicity and possible treatments for radiation-induced urethritis are discussed.

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.