Association of the Placement of a Perirectal Hydrogel Spacer With the Clinical Outcomes of Men Receiving Radiotherapy for Prostate Cancer: A Systematic Review and Meta-analysis

Risk Estimation of Late Rectal Toxicity Using a Convolutional Neural Network-based Dose Prediction in Prostate Cancer Radiation Therapy

Purpose

The present study investigated the feasibility of our automatic plan generation model based on a convolutional neural network (CNN) to estimate the baseline risk of grade ≥2 late rectal bleeding (G2-LRB) in volumetric modulated arc therapy for prostate cancer.

Methods and Materials

We built the 2-dimensional U-net model to predict dose distributions using the planning computed tomography and organs at risk masks as inputs. Seventy-five volumetric modulated arc therapy plans of prostate cancer, which were delivered at 74.8 Gy in 34 fractions with a uniform planning goal, were included: 60 for training and 5-fold cross-validation, and the remaining 15 for testing. Isodose volume dice similarity coefficient, dose-volume histogram, and normal tissue complication probability (NTCP) metrics between planned and CNN-predicted dose distributions were calculated. The primary endpoint was the goodness-of-fit, expressed as a coefficient of determination (R 2) value, in predicting the percentage of G2-LRB-Lyman-Kutcher-Burman-NTCP.

Results

In 15 test cases, 2-dimensional U-net predicted dose distributions with a mean isodose volume dice similarity coefficient value of 0.90 within the high-dose region (doses ≥ 50 Gy). Rectum V50Gy, V60Gy, and V70Gy were accurately predicted (R 2 = 0.73, 0.82, and 0.87, respectively). Strong correlations were observed between planned and predicted G2-LRB-Lyman-Kutcher-Burman-NTCP (R 2 = 0.80, P < .001), with a small percent mean absolute error (mean ± 1 standard deviation, 1.24% ± 1.42%).

Conclusions

A risk estimation of LRB using CNN-based automatic plan generation from anatomic information was feasible. These results will contribute to the development of a decision support system that identifies priority cases for preradiation therapy interventions, such as hydrogel spacer implantation.

Does biodegradable peri-rectal spacer mitigate treatment toxicities in radiation therapy for localised prostate cancer-a systematic review and meta-analysis

INTRODUCTION

There is an increasing use of biodegradable peri-rectal spacer prior to radiation therapy for prostate cancer to reduce treatment-associated rectal toxicity. While data from individual trials and cohorts is maturing, there is a lack of an updated quantitative analysis that includes outcomes following peri-rectal spacer. We aim to delineate the clinical impact of peri-rectal spacer in localised prostate cancer patients treated with radiotherapy.

METHODS

In March 2024, a systematic search was performed on MEDLINE, Embase, and Cochrane Central Register of controlled trials for publications since the year 2010. Prospective and retrospective studies reporting comparative outcomes of patients with and without peri-rectal spacer prior to radiotherapy were considered. Outcomes are reported in binary fashion. Random effect meta-analysis with the use of weighted mean difference was adopted. Early (≤3 months) and late rectal toxicity stratified according to the Common Terminology Criteria for Adverse Events (CTCAE) criteria, early and late genitourinary toxicity, quality of life in bowel, sexual and urinary domains (in terms of minimal clinically important difference) were assessed.

RESULTS

The systematic review included 17 studies. There are 3 RCTs, 3 prospective cohorts, and 11 retrospective cohorts. Three thousand two hundred patients were included, with 1471 patients who received peri-rectal spacer and 1729 without. The use of spacer is associated with lower likelihood of late (1.62% vs. 9.35%, RR = 0.25, 95% CI = 0.15-0.42, P < 0.001) and early grade 2 or above late rectal toxicity (3.07% vs. 6.05%, RR = 0.53, 95% CI = 0.33-0.86, P < 0.001). No difference is observed in significant grade 3 or above GI (acute or late) events. There is no statistical difference in bowel-related bowel QoL (risk difference = -0.16, 95% CI = -0.38-0.06, P = 0.15). The perirectal spacer is not associated with negative impact to urinary or sexual domains of QoL either.

CONCLUSION

In localised prostate cancer patients treated with radiation therapy, the use of peri-rectal spacer is associated with reduced rectal toxicities.

Bowel Disorder Incidence and Rectal Spacer Use in Patients With Prostate Cancer Undergoing Radiotherapy

Importance

The polyethylene glycol-based hydrogel spacer (PHS) system temporarily separates the rectum from the prostate in patients undergoing radiotherapy (RT) for prostate cancer (PCa).

Objective

To compare incidence of bowel disorders and related procedures in patients receiving RT with and without PHS.

Design, Setting, and Participants

This retrospective cohort study used 4 datasets: Medicare 5% Standard Analytic Files, Medicare 100% Standard Analytic Files, Merative MarketScan Commercial Database, and Premier Healthcare Database. Participants included adult patients with PCa undergoing RT from 2015 to 2021.

Exposure

Placement of PHS.

Main Outcomes

All-cause bowel disorders and related procedures, identified from diagnosis and procedure codes. Results were compared with age-matched male general population without PCa or RT.

Results

Of 261 906 patients with PCa included in the study, 25 167 (9.6%) received PHS (mean [SD] age, 70.7 [6.5] years) and 236 739 did not (mean [SD] age, 71.1 [7.5] years). One year prior to RT, patients who received PHS had a lower mean (SD) Charlson Comorbidity Index score than those who did not (2.48 [1.08] vs 3.14 [1.95]; P < .001). Stereotactic RT was more common in patients who received PHS (2743 [10.9%] vs 8810 [3.7%]; P < .001), while intensity-modulated RT was less common (12 755 [50.7%] vs 142 402 [60.2%]; P < .001). After 4 years post RT, patients who received PHS had a 25% lower hazard of bowel disorders (hazard ratio [HR], 0.75 [95% CI, 0.72-0.78]; P < .001) and a 46% lower hazard of related procedures (HR, 0.54 [95% CI, 0.47-0.62]; P < .001) than patients who did not receive PHS. Patients without PHS had higher hazard compared with an age-matched general population (disorders: 17.1% [95% CI, 17.3%-17.6%] vs 10.3% [95% CI, 10.1%-10.5%]; HR, 1.35 [95% CI, 1.32-1.37]; P < .001; procedures: 2.0% [95% CI, 1.9%-2.1%] vs 0.7% [95% CI, 0.7%-0.8%]; HR, 1.92 [95% CI, 1.79-2.06]; P < .001), while patients who received PHS did not (disorders: 12.4% vs 10.3%; HR, 1.00 [95% CI, 0.98-1.05]; P = .82; procedures: 1.1% [95% CI, 1.0%-1.3%] vs 0.7% [95% CI, 0.7%-0.8%]; HR, 1.11 [95% CI, 0.96-1.29]; P = .15). Common procedures included colonoscopy, sigmoidoscopy, and rectal resection.

Conclusions and Relevance

In this cohort study of patients with PCa receiving RT, those receiving a PHS had a significantly lower incidence of all-cause bowel disorders and related procedures compared with patients who did not receive a PHS over the 4-year follow-up. The incidence among patients with PHS was similar to the general population. These findings are consistent with prior phase 3 trial results, where patients receiving PHS experienced no decline in bowel quality of life.

Efficacy and Safety of Newly Installed Spot Scanning Proton Beam Therapy for Prostate Cancer

BACKGROUND/AIM

This study aimed to analyse retrospectively the initial treatment outcomes and associated toxicities of a spot scanning proton beam therapy for prostate cancer at the Shonan-Kamakura General Hospital.

PATIENTS AND METHODS

A laterally opposing single-field uniform dose of spot-scanning proton beam was used. The doses were determined to be 60 Gy in 20 fractions for low-risk prostate cancer and 63 Gy in 21 fractions for intermediate- and high-risk prostate cancers. Genitourinary (GU) and gastrointestinal (GI) toxicities were also evaluated. Toxicity was assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

RESULTS

A total of 135 patients were treated over two years, 51 of whom underwent hydrogel spacer insertion. During the limited observation period, no patient experienced a recurrence. Grade 2 GU toxicities were observed in 17 patients, whereas grade 1 or greater GI toxicities were observed in seven patients. None of the patients in whom a hydrogel spacer was inserted experienced grade 1 or higher GI toxicity.

CONCLUSION

Proton beam therapy is safe for the treatment of prostate cancer. The insertion of a gold marker and hydrogel spacer led to a reduction in the rectal radiation dose and GI toxicity.

Radical Prostatectomy Versus Stereotactic Radiotherapy for Clinically Localised Prostate Cancer: Results of the PACE-A Randomised Trial

BACKGROUND AND OBJECTIVE

Randomised data on patient-reported outcomes (PROs) for stereotactic body radiotherapy (SBRT) and prostatectomy in localised prostate cancer are lacking. PACE-A compared patient-reported health-related quality of life after SBRT with that after prostatectomy.

METHODS

PACE is a phase 3 open-label, randomised controlled trial. PACE-A randomised men with low- to intermediate-risk localised prostate cancer to SBRT or prostatectomy (1:1). Androgen deprivation therapy (ADT) was not permitted. The coprimary outcomes were the Expanded Prostate Index Composite (EPIC-26) number of absorbent urinary pads required daily and bowel domain score at 2 yr. The secondary endpoints were clinician-reported toxicity, sexual functioning, and other PROs.

KEY FINDINGS AND LIMITATIONS

In total, 123 men were randomised (60 undergoing prostatectomy and 63 SBRT) from August 2012 to February 2022. The median follow-up time was 60.7 mo. The median age was 65.5 yr and the median prostate-specific antigen (PSA) value 7.9 ng/ml; 92% had National Comprehensive Cancer Network (NCCN) intermediate-risk disease. Fifty participants received prostatectomy and 60 received SBRT. At 2 yr, 16/32 (50%) prostatectomy and three of 46 (6.5%) SBRT participants used one or more urinary pads daily (p < 0.001; 15 and two, respectively, used one pad daily); the estimated difference was 43% (95% confidence interval [CI]: 25%, 62%). At 2 yr, bowel scores were better for prostatectomy (median [interquartile range] 100 [100-100]) than for SBRT (87.5 [79.2-100]; p < 0.001), with an estimated mean difference of 8.9 between these (95% CI: 4.2, 13.7); sexual scores were worse for prostatectomy (18 [13.8-40.3]) than for SBRT (62.5 [32.0-87.5]). The limitations were slow recruitment and incomplete 2-yr PRO response rates.

CONCLUSIONS AND CLINICAL IMPLICATIONS

SBRT was associated with less patient-reported urinary incontinence and sexual dysfunction, and slightly more bowel bother than prostatectomy. These randomised data should inform treatment decision-making for patients with localised, intermediate-risk prostate cancer.

A phase I clinical trial evaluating the application of hydrogel in reducing rectal dose during cervical cancer brachytherapy

Purpose

This study represents a prospective phase I clinical research to verify the effectiveness and reliability of hydrogel application in Chinese cervical cancer patients.

Materials and Methods

Eight patients were enrolled in the study. After completing intensity-modulated radiotherapy at 50.4 Gy/28 fractions, a 10 mL injection of hydrogel was administered to each patient through the posterior vaginal fornix under CT-guidance. Image-guided brachytherapy under CT or MRI guidance was given with a target dose of 6 Gy in 5 fractions to the high-risk clinical target volume. Rectal, sigmoid colon, and bladder D2cm3 were recorded for each brachytherapy. MRI scans were performed to measure the distance between the rectum and the cervix or tumor, as well as the spacer gel volume. Patients' QLQ-C30 and QLQ-CX24 scores were recorded to assess treatment outcomes, and all adverse events were documented.

Results

Among the eight patients, the average D2cc was 60.9 ± 3.4 Gy for the rectum, 64.7 ± 6.8 Gy for sigmoid colon and 77.1 ± 7.4 Gy for bladder, respectively. The distance between the cervix and rectum significantly increased after gel injection. None of the eight patients experienced grade 3 or higher acute toxic reactions during brachytherapy. None patient experienced late rectal toxicity. No adverse events definitively associated with the hydrogel were observed. Patients' subjective quality of life scores did not significantly change before and after gel injection. The reduction ro the volume of the hydrogel were observed during the 24 to 36  weeks after injection.

Conclusion

The application of the hydrogel effectively increased the distance between the cervix and rectum in brachytherapy for cervical cancer, limiting the rectal dose without increasing doses to other critical organs. In the short term, no severe adverse events were observed, indicating the safety and reliability of this approach. Further research is warranted to confirm its long-term safety and effectiveness.

French AFU Cancer Committee Guidelines - Update 2024-2026: Prostate cancer - Diagnosis and management of localised disease

OBJECTIVE

The aim of the Oncology Committee of the French Urology Association is to propose updated recommendations for the diagnosis and management of localized prostate cancer (PCa).

METHODS

A systematic review of the literature from 2022 to 2024 was conducted by the CCAFU on the elements of diagnosis and therapeutic management of localized PCa, evaluating references with their level of evidence.

RESULTS

The recommendations set out the genetics, epidemiology and diagnostic methods of PCa, as well as the concepts of screening and early detection. MRI, the reference imaging test for localized cancer, is recommended before prostate biopsies are performed. Molecular imaging is an option for disease staging. Performing biopsies via the transperineal route reduces the risk of infection. Active surveillance is the standard treatment for tumours with a low risk of progression. Therapeutic methods are described in detail, and recommended according to the clinical situation.

CONCLUSION

This update of French recommendations should help to improve the management of localized PCa.

Overview of Radiation Therapy in the Management of Localized and Metastatic Prostate Cancer

PURPOSE OF REVIEW

The goal is to describe the evolution of radiation therapy (RT) utilization in the management of localized and metastatic prostate cancer.

RECENT FINDINGS

Long term data for a variety of hypofractionated definitive RT dose-fractionation schemes has matured, allowing patients and providers many standard-of-care options to choose from. Post-prostatectomy, adjuvant RT has largely been replaced by an early salvage approach. Multiparametric MRI and PSMA PET have enabled increasingly targeted RT delivery to the prostate and oligometastatic tumors. Areas of active investigation include determining the value of proton beam therapy and perirectal spacers, and optimally incorporate genomic tumor profiling and next generation hormonal therapies with RT in the curative setting. The use of radiation therapy to treat prostate cancer is rapidly evolving. In the coming years, there will be continued improvements in a variety of areas to enhance the value of RT in multidisciplinary prostate cancer management.

The role of a radiopaque peri-rectal hydrogel spacer in aiding accurate daily image-guidance for prostate stereotactic radiotherapy

Introduction

Precise patient positioning with image guidance (IGRT) is essential for safe prostate radiotherapy. We present the first report of utilizing a CT-visible hydrogel spacer, used to decrease rectal radiation dose, as a surrogate fiducial marker to aid in daily IGRT with cone-beam CT (CBCT) in stereotactic radiotherapy (SABR) for prostate cancer.

Materials and methods

Prior to CT simulation, patients underwent placement of three intraprostatic gold fiducial markers and radiopaque hydrogel spacer per standard practice. At treatment, after initial setup, a CBCT was acquired and fused to the planning CT based on 3-dimensional matching of the spacer. A second alignment was then performed based on the fiducial markers. The six directional shifts (three linear and three rotational) were recorded, and the differences compared.

Results

140 individual fractions across 41 consecutive patients were evaluated. Mean/median differences between hydrogel spacer-based and fiducial-based alignment in linear (vertical, longitudinal, lateral) and rotational (rotation, pitch, roll) shifts were 0.9/0.6mm, 0.8/0.5mm, and 0.6/0.4mm, and 0.38/0, 0.62/0, and 0.35/0 degrees, respectively. No difference was observed in 9.9%, 22.9%, and 22.14% of linear shifts, and 65.7%, 65%, and 66.4% rotational shifts, respectively. Significantly smaller differences were observed in the latter 70 fractions vs. the former, and results were consistent across evaluators.

Conclusions

For precise daily IGRT with CBCT for prostate SABR, alignment using a radiopaque hydrogel spacer was highly comparable to intraprostatic fiducial markers. This represents the first report supporting an additional indication of IGRT for a CT-visible hydrogel spacer, to further enhance treatment accuracy and potentially obviate the need for the additional fiducial marker procedure.

Applications of self-assembled peptide hydrogels in anti-tumor therapy

Peptides are a class of active substances composed of a variety of amino acids with special physiological functions. The rational design of peptide sequences at the molecular level enables their folding into diverse secondary structures. This property has garnered significant attention in the biomedical sphere owing to their favorable biocompatibility, adaptable mechanical traits, and exceptional loading capabilities. Concurrently with advancements in modern medicine, the diagnosis and treatment of tumors have increasingly embraced targeted and personalized approaches. This review explores recent applications of self-assembled peptides derived from natural amino acids in chemical therapy, immunotherapy, and other adjunctive treatments. We highlighted the utilization of peptide hydrogels as delivery systems for chemotherapeutic drugs and other bioactive molecules and then discussed the challenges and prospects for their future application.

Evaluation of Delivered Doses in Proton Beam Therapy for Prostate Cancer Using Positron Emission Tomography/Computed Tomography Imaging

AIMS

Proton beams deposit energy along their paths and stop abruptly without penetrating the opposite side, making it difficult to detect their actual paths. However, confirming the path may lead to evaluating the actual doses to organs at risk in proton therapy for prostate cancer. As proton beams produce positron emitters through nuclear fragmentation reactions, theoretically, proton beam paths can be measured by positron emission tomography/computed tomography (PET/CT). Therefore, this study investigated whether conducting PET/CT examinations immediately after proton beam therapy helps to assess the doses delivered to the rectal and urinary bladder walls, which are the major sites of radiation-related toxicity.

MATERIALS AND METHODS

Between June 2022 and June 2023, 51 consecutive patients with prostate cancer who underwent proton beam therapy were enrolled and imaged with PET/CT to measure these radioactive particles and validate the actual dose delivered to the rectal and urinary bladder walls.

RESULTS

The delivered doses assessed using PET/CT after proton beam therapy strongly correlated with the planned volume for proton beam treatment.

CONCLUSIONS

PET/CT exhibited potential as a valuable tool for validating the irradiated dose to organs at risk.

A preliminary study on rectal dose reduction associated with hyaluronic acid implantation in brachytherapy for prostate cancer

Objectives

Hydrogel spacer (HS) was developed to reduce rectal toxicities caused by radiotherapy, but has been reported to cause major adverse events. Our institute has attempted to introduce a hyaluronic acid (HA) as an alternative spacer. This study aimed to compare rectal doses and geometric distributions between the HS and HA implantation in prostate cancer.

Methods

HS and HA were inserted in 20 and 18 patients undergoing high-dose brachytherapy, respectively. The rectum spacer volumes injected were 10 mL and 22 mL, respectively. In the treatment planning system, 13.5 Gy was administered with common catheter positions. The rectal dose indices were assessed between the spacer groups for dosimetry evaluation. Distances between the prostate and rectum and configurations of the spacers were compared.

Results

The mean doses irradiated to 0.1 and 2 mL of the rectum were 10.45 Gy and 6.71 Gy for HS, and 6.73 Gy and 4.90 Gy for HA (p<0.001). The mean minimum distances between the prostate and rectum were 1.23 cm and 1.79 cm for HS and HA, respectively (p<0.05). Geometrical configuration comparisons revealed that HA has a higher ability to expand the space than HS.

Conclusion

The rectal dose reduction ability of HA is significantly greater than that of HS, suggesting its potential as a new spacer.

Is motherhood still possible after pelvic carbon ion radiotherapy? A promising combined fertility-preservation approach

INTRODUCTION

Preserving the endocrine and reproductive function in young female cancer patients undergoing pelvic radiation is a significant challenge. While the photon beam radiation's adverse effects on the uterus and ovaries are well established, the impact of pelvic carbon ion radiotherapy on women's reproductive function is largely unexplored. Strategies such as oocyte cryopreservation and ovarian transposition are commonly recommended for safeguarding future fertility.

METHODS

This study presents a pioneering case of successful pregnancy after carbon ion radiotherapy for locally advanced sacral chondrosarcoma.

RESULTS

A multidisciplinary approach facilitated the displacement of ovaries and uterus before carbon ion radiotherapy, resulting in the preservation of endocrine and reproductive function.

CONCLUSION

The patient achieved optimal oncological response and delivered a healthy infant following the completion of cancer treatment.

Validation of a Quality Metric Score to Assess the Placement of Hydrogel Rectal Spacer in Patients Treated With Prostate Stereotactic Radiation Therapy

Purpose

To evaluate the quality of the interspace between the prostate and rectum and assess the effect on the dose to the rectum by measuring the spacer quality score (SQS) before and after implanting a hydrogel rectal spacer.

Methods and Materials

Thirty patients with prostate cancer were treated with stereotactic ablative body radiation therapy as part of the SPORT clinical trial. Each patient had a 10 mL polyethylene glycol hydrogel spacer inserted transperineally. Computed tomography scans were acquired before and after spacer insertion, 10MV flattening filter free (FFF) stereotactic ablative body radiation therapy (SABR) treatment plans were generated using each image set. To calculate the SQS, the prostate-rectal interspace (PRI) was measured in the anterior-posterior orientation, parallel to the anatomic midline at the prostate base, apex, and midgland on the prespacer and postspacer computed tomography. Measurements were taken in 3 transverse positions between the prostate and the rectum, and PRI scores of 0, 1, and 2 were assigned if the interspace between prostate and rectum was <0.3, 0.3 to 0.9, or ≥1 cm, respectively. The overall SQS was the lowest of the PRI scores. Differences between prespacer and postspacer PRIs and SQS were investigated by performing Fisher's exact test and differences between doses to the rectum were investigated by performing the paired samples Wilcoxon rank-sum test and Student t test.

Results

Statistically significant differences between prespacer versus postspacer patients were found when grouping patients according to their overall SQS. The PRI summary score did not reach statistical significance between prespacer and postspacer at the base but was significantly higher for the prostate midline and apex. Statistically significant differences in some rectum dose-volume metrics were found when grouping patients according to their PRIs and SQS.

Conclusions

SQS before and after the spacer insertion was evaluated and was found to be correlated with pre- and postspacer rectal dosimetry. Sources of improvement of the SQS scoring metric and limitations are discussed.

One-year clinical outcomes of MR-guided stereotactic body radiation therapy with rectal spacer for patients with localized prostate cancer

BACKGROUND AND PURPOSE

This prospective study aimed to investigate adaptive magnetic resonance (MR)-guided stereotactic body radiation therapy (MRgSBRT) with rectal spacer for localized prostate cancer (PC) and report 1-year clinical outcomes.

MATERIALS AND METHODS

Thirty-four consecutive patients with low- to high-risk localized PC that underwent 5-fraction adaptive MRgSBRT with rectal spacer were enrolled. The dosimetric comparison was performed on a risk- and age-matched cohort treated with MRgSBRT but without a spacer at a similar timepoint. Clinician-reported outcomes were based on Common Terminology Criteria for Adverse Events. Patient-reported outcomes were based on the Expanded Prostate Cancer Index Composite (EPIC) questionnaire at baseline, acute (1-3 months), subacute (4-12 months), and late (> 12 months) phases.

RESULTS

The median follow-up was 390 days (range 28-823) and the median age was 70 years (range 58-82). One patient experienced rectal bleeding soon after spacer insertion that subsided before MRgSBRT. The median distance between the midline of the prostate midgland and the rectum after spacer insertion measured 7.8 mm (range 2.6-15.3), and the median length of the spacer was 45.9 mm (range 16.8-62.9) based on T2-weighted MR imaging. The use of spacer resulted in significant improvements in target coverage (V100% > 95% = 98.6% [range 93.4-99.8] for spacer vs. 97.8% [range 69.6-99.7] for non-spacer) and rectal sparing (V95% < 3 cc = 0.7 cc [range 0-4.6] for spacer vs. 4.9 cc [range 0-12.5] for non-spacer). Nine patients (26.5%) experienced grade 1 gastrointestinal toxicities, and no grade ≥ 2 toxicities were observed. During the 1-year follow-up period, EPIC scores for the bowel domain remained stable and were the highest among all other domains.

CONCLUSIONS

MRgSBRT with rectal spacer for localized PC showed exceptional tolerability with minimal gastrointestinal toxicities and satisfactory patient-reported outcomes. Improvements in dosimetry, rectal sparing, and target coverage were achieved with a rectal spacer. Randomized trials are warranted for further validation.

Characterization of an Injectable Chitosan Hydrogel for the Tunable, Localized Delivery of Immunotherapeutics

Localized delivery of immunotherapeutics within a tumor has the potential to reduce systemic toxicities and improve treatment outcomes in cancer patients. Unfortunately, local retention of therapeutics following intratumoral injection is problematic and is insufficiently considered. Dense tumor architectures and high interstitial pressures rapidly exclude injections of saline and other low-viscosity solutions. Hydrogel-based delivery systems, on the other hand, can resist shear forces that cause tumor leakage and thus stand to improve the local retention of coformulated therapeutics. The goal of the present work was to construct a novel, injectable hydrogel that could be tuned for localized immunotherapy delivery. A chitosan-based hydrogel, called XCSgel, was developed and subsequently characterized. Nuclear magnetic resonance studies were performed to describe the chemical properties of the new entity, while cryo-scanning electron microscopy allowed for visualization of the hydrogel's cross-linked network. Rheology experiments demonstrated that XCSgel was shear-thinning and self-healing. Biocompatibility studies, both in vitro and in vivo, showed that XCSgel was nontoxic and induced transient mild-to-moderate inflammation. Release studies revealed that coformulated immunotherapeutics were released over days to weeks in a charge-dependent manner. Overall, XCSgel displayed several clinically important features, including injectability, biocompatibility, and imageability. Furthermore, the properties of XCSgel could also be controlled to tune the release of coformulated immunotherapeutics.

Functional Outcomes After Localized Prostate Cancer Treatment

Importance

Adverse outcomes associated with treatments for localized prostate cancer remain unclear.

Objective

To compare rates of adverse functional outcomes between specific treatments for localized prostate cancer.

Design, Setting, and Participants

An observational cohort study using data from 5 US Surveillance, Epidemiology, and End Results Program registries. Participants were treated for localized prostate cancer between 2011 and 2012. At baseline, 1877 had favorable-prognosis prostate cancer (defined as cT1-cT2bN0M0, prostate-specific antigen level <20 ng/mL, and grade group 1-2) and 568 had unfavorable-prognosis prostate cancer (defined as cT2cN0M0, prostate-specific antigen level of 20-50 ng/mL, or grade group 3-5). Follow-up data were collected by questionnaire through February 1, 2022.

Exposures

Radical prostatectomy (n = 1043), external beam radiotherapy (n = 359), brachytherapy (n = 96), or active surveillance (n = 379) for favorable-prognosis disease and radical prostatectomy (n = 362) or external beam radiotherapy with androgen deprivation therapy (n = 206) for unfavorable-prognosis disease.

Main Outcomes and Measures

Outcomes were patient-reported sexual, urinary, bowel, and hormone function measured using the 26-item Expanded Prostate Cancer Index Composite (range, 0-100; 100 = best). Associations of specific therapies with each outcome were estimated and compared at 10 years after treatment, adjusting for corresponding baseline scores, and patient and tumor characteristics. Minimum clinically important differences were 10 to 12 for sexual function, 6 to 9 for urinary incontinence, 5 to 7 for urinary irritation, and 4 to 6 for bowel and hormone function.

Results

A total of 2445 patients with localized prostate cancer (median age, 64 years; 14% Black, 8% Hispanic) were included and followed up for a median of 9.5 years. Among 1877 patients with favorable prognosis, radical prostatectomy was associated with worse urinary incontinence (adjusted mean difference, -12.1 [95% CI, -16.2 to -8.0]), but not worse sexual function (adjusted mean difference, -7.2 [95% CI, -12.3 to -2.0]), compared with active surveillance. Among 568 patients with unfavorable prognosis, radical prostatectomy was associated with worse urinary incontinence (adjusted mean difference, -26.6 [95% CI, -35.0 to -18.2]), but not worse sexual function (adjusted mean difference, -1.4 [95% CI, -11.1 to 8.3), compared with external beam radiotherapy with androgen deprivation therapy. Among patients with unfavorable prognosis, external beam radiotherapy with androgen deprivation therapy was associated with worse bowel (adjusted mean difference, -4.9 [95% CI, -9.2 to -0.7]) and hormone (adjusted mean difference, -4.9 [95% CI, -9.5 to -0.3]) function compared with radical prostatectomy.

Conclusions and Relevance

Among patients treated for localized prostate cancer, radical prostatectomy was associated with worse urinary incontinence but not worse sexual function at 10-year follow-up compared with radiotherapy or surveillance among people with more favorable prognosis and compared with radiotherapy for those with unfavorable prognosis. Among men with unfavorable-prognosis disease, external beam radiotherapy with androgen deprivation therapy was associated with worse bowel and hormone function at 10-year follow-up compared with radical prostatectomy.

Application of a Radiopaque Viscous Hydrogel Spacer for Prostate Cancer Radiation Therapy: A Prospective Phase 2 Study

PURPOSE

The aim of this study was to evaluate the application of a radiopaque viscous spacer (RVS) for prostate cancer radiation therapy (RT), including injection procedure, toxicity, treatment planning, image guidance, and imaging results up to 12 months after RT.

METHODS AND MATERIALS

RVS (median, 10 mL) was injected between prostate and rectal wall in 30 patients. Cone beam computed tomography (CT) was performed during the course of RT, a magnetic resonance imaging 3 and 12 months after RT. Injection and treatment tolerability were analyzed. The resulting distribution was compared with a control group of 30 patients with an initially fluid spacer.

RESULTS

Procedure- or device-related adverse events were not observed. Signs of hydrogel migration were not found in any case. The volume decreased by 25% at 3 months after RT, and small residues were detected at 12 months after RT in 3 cases (10%). The median rectal volume percentage within the 90% isodose was 3.0% (interquartile range, 1.5%-4.5%). Acute and late gastrointestinal toxicities were found in 17% and 3%, respectively (all grade 1). The median distance between prostate and rectum at the base/midplane/apex was greater for RVS in comparison to initially fluid spacer (14/12/11 mm vs 12/10/10 mm, respectively), the gel symmetry (right vs left from midline) was comparable. The application was assessed to be easier to control by the users, and visibility in cone beam CT as good.

CONCLUSIONS

The injection of a radiopaque viscous hydrogel spacer resulted in a prostate-rectum distance of >10 mm in most cases. The resulting rectum volume within the high-dose region and RT toxicity were very low. Advantages in comparison to the conventional hydrogel spacer are predominantly an improved placement control during the injection process and good visibility on CT.

Real-World Complications of the SpaceOAR Hydrogel Spacer: A Review of the Manufacturer and User Facility Device Experience Database

OBJECTIVE

To characterize adverse events related to use of the perirectal spacing agent SpaceOAR, we examined the Manufacturer and User Facility Device Experience (MAUDE) database.

METHODS

The MAUDE database was queried for "SpaceOAR" and "Augmenix" from June 2015 (when SpaceOAR was approved by the Food and Drug Administration) to October 2022. Reports were reviewed for adverse events (AEs), operative procedures performed because of the AE, and changes to the radiation plan. AEs were categorized using Common Terminology Criteria for Adverse Events (CTCAE), version 5.0.

RESULTS

Six hundred fifty-four reports were reviewed. Eighty-four were excluded and 4 reports reviewed 2 separate cases of SpaceOAR administration. Five hundred seventy-four cases were ultimately included. Three deaths were reported (0.5% of all AEs). One point six percent of cases represented CTCAE grade 4 injuries (life-threatening consequences; urgent intervention indicated), 15.9% grade 3 (severe but not immediately life-threatening; hospitalization), 24.2% grade 2 (moderate; local/noninvasive intervention), and 57% of events were CTCAE grade 1 (mild; asymptomatic or mild symptoms). Bowel diversion occurred in 29 cases (9%).

CONCLUSION

Both asymptomatic (n = 311) and debilitating (n = 12) complications of SpaceOAR hydrogel use were identified. Death, gel embolization, anaphylaxis, rectal ulcerations, and infections requiring bowel or urinary diversions were among the complications reviewed. Providers should consider these potential complications before perirectal spacer administration and during patient counseling.

Upper rectal fixation with an endorectal balloon in prostate cancer radiotherapy

Purpose

Despite the efficacy of endorectal balloon (ERB) in reducing rectal radiation dose, the effectiveness of upper rectal fixation remains to be evaluated. The purpose of this study was to evaluate the impact of ERB on upper rectal fixation in patients diagnosed with localized prostate cancer.

Materials

Cine MRI was performed in 46 patients with localized prostate cancer to assess the stability of the anterior rectal wall with and without ERB by calculating the standard deviation of the normalized signal intensity at the level of the midgland or the seminal vesicle.

Results

The standard deviation of the normalized signal intensity for the anterior rectal wall decreased significantly with the use of ERB both at the level of the midgland (p < 0.05) and the seminal vesicle (p < 0.05). The standard deviation of the anterior rectal wall at the level of the seminal vesicle was significantly higher than at the level of the midgland without ERB (p < 0.05). But with ERB, the standard deviation of the normalized signal intensity at the level of the seminal vesicle became comparable to that at the level of the midgland (p = 0.392).

Conclusion

The anterior rectal wall is stabilized by ERBs not only at the level of the midgland but also at the level of the seminal vesicle. ERBs can transform the rectum from a moving and deformable organ into a static and rigid organ.

Effect of Transperineal Versus Transrectal Prostate Biopsy on the Quality of Hydrogel Spacer Placement in Men Prior to Radiation Therapy for Prostate Cancer

OBJECTIVE

To determine whether prostate biopsy type affects spacer placement quality using a large sample of patients treated in the ambulatory setting.

METHODS

A retrospective cohort study was conducted on patients diagnosed with prostate cancer who underwent hydrogel spacer placement before primary radiation treatment between 2018 and 2023 after transperineal (TP) or transrectal (TR) prostate biopsy. Study outcomes were Spacer Quality Score (SQS) (0-2, with greater values indicating better placement), Rectal Wall Infiltration (RWI) (0-3, with lower values indicating lack of RWI), and the occurrence of other hydrogel complications.

RESULTS

A total of 395 patients were included. A pre-hydrogel TR biopsy was performed in 273 patients (69.1%), while TP biopsy was performed in 122 (30.9%). A SQS ≥1 occurred in 308 (77.9%) patients. A greater proportion of TP patients had a favorable SQS (≥1) compared to those who underwent TR (87.7 vs 73.5%, P <.002). An RWI score ≥2 was found in 180 (45.6%) patients. The proportion of patients with an unfavorable RWI score (≥2) did not differ significantly by type of biopsy performed. Patients who had an interval of >70 days between biopsy and hydrogel placement had significantly decreased odds of an RWI score ≥2 (odds ratio = 0.42, 95% confidence interval: 0.21-0.83). Only one infection was found after hydrogel placement.

CONCLUSION

The quality of hydrogel placement was significantly better in men who had undergone TP biopsy. Rectal wall infiltration was more common than previously reported but did not differ between TP and TR biopsies.

Use of Perirectal Hyaluronic Acid Spacer Prior to Radiotherapy in a Pediatric Patient With Bladder Rhabdomyosarcoma: A Case Report

Rhabdomyosarcoma (RMS) treatment involves surgery, chemotherapy, and radiotherapy. A radioprotective space between the bladder/prostate and rectum reduces postradiation complications, as reported in adult patients. Describe pediatric preradiotherapy perirectal hyaluronic acid (HA) spacer injection for bladder/prostate RMS. We present a case of a 17-month-old male with bladder/prostate RMS. Before radiotherapy, an HA spacer was injected peri-rectally. Under general anesthesia, a transrectal ultrasound was positioned and 1mL of HA spacer was injected into the perirectal space. No complications were reported at 6-month follow-up. This is the first report of pre-radiation therapy spacer injection for pediatric bladder/prostate RMS.

Increasing rectum-prostate distance using a hydrogel spacer to reduce radiation exposure during proton beam therapy for prostate cancer

SpaceOAR, a polyethylene-glycol hydrogel, reduces rectal radiation exposure during radiation therapy for prostate cancer. Previously, our group reported the modified technique of hydrogel insertion, which achieves greater separated distance at prostate-apex. This study aimed to investigate the impact of separated distance at prostate-apex and our modifier technique, on radiation exposure reduction during proton beam therapy (PBT). We included 330 patients undergoing PBT with the relative biological effectiveness (RBE) of 63 Gray (Gy) for localized prostate cancer, and categorized them into groups 0 (no spacer, n = 141), 1 (separated distance of spacer at the prostate-apex level < 7.5 mm, n = 81), and 2 (distance ≥ 7.5 mm, n = 108). The rectal volumes to receive 30-60 Gy (RBE), was estimated and described as Rectal V30-60 (ml) in 10 Gy increments. The Rectal V30-60 (ml) was significantly lower in group 2 than in group 1, and in group 1 than in group 0. After propensity score matching, the multivariate logistic regression analysis revealed that the most significant factor to reduce radiation exposure was our modified technique of hydrogel insertion. Therefore, using a hydrogel spacer to expand the prostate-rectum distance not only at prostate-mid to prostate-base level but also at the prostate-apex level can reduce the radiation exposure in PBT for prostate cancer.

Prostate-specific antigen kinetics in hypofractionated radiation therapy alone for intermediate- and high-risk localized prostate cancer

Background

This study aimed to evaluate the treatment outcomes and define the prostate-specific antigen (PSA) kinetics as potential prognostic factors in patients with intermediate- or high-risk localized prostate cancer (PCa) who underwent moderately hypofractionated radiation therapy.

Methods

The study retrospectively reviewed the medical records of 149 patients with intermediate- or high-risk localized PCa who underwent definitive radiation therapy (70 Gy in 28 fractions) without androgen deprivation therapy. Clinical outcomes were analyzed based on risk stratification (favorable-intermediate, unfavorable-intermediate, and high-risk). The biochemical failure rate (BFR) and clinical failure rate (CFR) were stratified based on the PSA nadir and the time to the PSA nadir to identify the prognostic effect of PSA kinetics. Acute and late genitourinary and gastrointestinal adverse events were analyzed.

Results

Significant differences were observed in the BFR and CFR according to risk stratification. No recurrence was observed in the favorable intermediate-risk group. The 7-year BFR and CFR for the unfavorable intermediate-risk and high-risk groups were 19.2% and 9.8%, and 31.1% and 25.3%, respectively. Patients with a PSA nadir >0.33 ng/mL or a time to the PSA nadir <36 months had a significantly greater BFR and CFR. The crude rate of grade 3 late adverse events was 3.4% (genitourinary: 0.7%; gastrointestinal: 2.7%). No grade 4-5 adverse event was reported.

Conclusion

A significant difference in clinical outcomes was observed according to risk stratification. The PSA nadir and time to the PSA nadir were strongly associated with the BFR and CFR. Therefore, PSA kinetics during follow-up are important for predicting prognosis.

The Current Trend of Radiation Therapy for Patients with Localized Prostate Cancer

A recent approach to radiotherapy for prostate cancer is the administration of high doses of radiation to the prostate while minimizing the risk of side effects. Thus, image-guided radiotherapy utilizes advanced imaging techniques and is a feasible strategy for increasing the radiation dose. New radioactive particles are another approach to achieving high doses and safe procedures. Prostate brachytherapy is currently considered as a combination therapy. Spacers are useful to protect adjacent organs, specifically the rectum, from excessive radiation exposure.

Clinical Experience and Feasibility of Using 2D-kVimage Online Intervention in the Ultrafractionated Stereotactic Radiation Treatment of Prostate Cancer

PURPOSE

This study reports clinical experience and feasibility of using a 2-dimensional (2D)-kV image system with online intervention in the ultrafractionated stereotactic body radiation treatment (UF-SBRT) of prostate cancer.

METHODS AND MATERIALS

Fifteen patients with prostate cancer who had a low- to intermediate-risk marker implanted received UF-SBRT with online 2D-kV image tracking and a manual beam interruption strategy with a 2-mm motion threshold. A total of 180 kV paired setup images and 1272 intrabeam 2D-kV images were analyzed to evaluate the setup deviation and intratreatment target deviation. Correlation of expected treatment interruptions with a set of parameters (eg, image and treatment time; direction of deviation) was performed (Spearman test). A subset of the data from 22 fractions was re-evaluated to check the differences in analysis results between using the planning position and using the pretreatment setup position as a reference. Margins based on the derived system and random errors were calculated to evaluate the feasibility of the workflow in ensuring prostate coverage during treatment.

RESULTS

Mean target motion in 3D propagated from 1.0 mm (setup at 0 minutes) to 2.0 mm (beam on at 7 minutes) to 2.4 mm (end at 13.5 minutes). Out of 75 fractions, 50 were found to require beam interruption. Interruption had a strong correlation with prostate motion along the longitudinal direction and had moderate correlation with prostate motion along the vertical direction and the prostate's treatment starting position along vertical and longitudinal directions. Using the pretreatment position as a reference for intrabeam monitoring, the magnitude of motion deviation from the reference position was reduced by 0.3 mm at a vertical direction and 0.4 mm at lateral and longitudinal directions. The calculated 3D margin to ensure target coverage was 3.7 mm, 4.6 mm, and 5.0 mm in lateral, vertical, and longitudinal directions, respectively.

CONCLUSIONS

Prostate motion propagated over time. It is feasible to use a 2D-kV online intrabeam monitoring system with a proper intervention scheme to perform UF-SBRT for prostate cancer.

Safety and efficacy associated with single-fraction high-dose-rate brachytherapy in localized prostate cancer: a systematic review and meta-analysis

OBJECTIVE

Although single-fraction high-dose-rate brachytherapy (SFHDR) for localized prostate cancer has been tried in clinical trials, relevant medical evidence is currently lacking. It is necessary to systematically analyze the safety and efficacy of SFHDR.

METHODS

Comprehensive and systematic searches for eligible studies were performed in PubMed, Embase, and the Cochrane Library databases. The primary endpoints included safety and efficacy, represented by toxic effects and biochemical recurrence-free survival (bRFS), respectively. The proportion rates were used as the effect measure for each study and were presented with corresponding 95% confidence intervals (CI) and related 95% prediction interval (PI). Restricted maximum-likelihood estimator (REML) and the Hartung-Knapp method were used in the meta-analysis.

RESULTS

Twenty-five studies met the inclusion criteria for quantitative analysis, including 1440 patients. The median age of patients was 66.9 years old (62-73 years old) and the median follow-up was 47.5 months (12-75 months). The estimates of cumulative occurrence for severe gastrointestinal (GI) and genitourinary (GU) toxic effects were 0.1% (95% CI 0-0.2%) and 0.4% (95% CI 0-1.2%), and for grade 2 toxic effects were 1.6% (95% CI 0.1-4.7%) and 17.1% (95% CI 5.4-33.5%), respectively. The estimate of 3‑year bRFS was 87.5% (95% CI 84.4-90.3%) and 71.0% (95% CI 63.0-78.3%) for 5‑year bRFS. The pooled bRFS rates for low-risk patients were 99.0% (95% CI 85.2-100.0%) at 3 years and 80.9% (95% CI 75.4-85.9%) at 5 years, and the risk group was found to be statistically correlated with bRFS (3-year bRFS, P < 0.01; 5‑year bRFS, P = 0.04).

CONCLUSION

SFHDR is associated with favorable tolerability and suboptimal clinical benefit in patients with localized prostate cancer. Ongoing and planned high-quality prospective studies are necessary to verify its safety and efficacy.

Rectal Cancer after Prostate Radiation: A Complex and Controversial Disease

A small proportion of rectal adenocarcinomas develop in patients many years after the treatment of a previous cancer using pelvic radiation, and the incidence of these rectal cancers depends on the length of follow-up from the end of radiotherapy. The risk of radiation-associated rectal cancer (RARC) is higher in patients treated with prostate external beam radiotherapy than it is in patients treated with brachytherapy. The molecular features of RARC have not been fully investigated, and survival is lower compared to non-irradiated rectal cancer patients. Ultimately, it is unclear whether the worse outcomes are related to differences in patient characteristics, treatment-related factors, or tumor biology. Radiation is widely used in the management of rectal adenocarcinoma; however, pelvic re-irradiation of RARC is challenging and carries a higher risk of treatment complications. Although RARC can develop in patients treated for a variety of malignancies, it is most common in patients treated for prostate cancer. This study will review the incidence, molecular characteristics, clinical course, and treatment outcomes of rectal adenocarcinoma in patients previously treated with radiation for prostate cancer. For clarity, we will distinguish between rectal cancer not associated with prostate cancer (RCNAPC), rectal cancer in non-irradiated prostate cancer patients (RCNRPC), and rectal cancer in irradiated prostate cancer patients (RCRPC). RARC represents a unique but understudied subset of rectal cancer, and thus requires a more comprehensive investigation in order to improve its treatment and prognosis.

Virtual HDR Boost for Prostate Cancer: Rebooting a Classic Treatment Using Modern Tech

Prostate cancer (PC) is the most common malignancy in men. Internal radiotherapy (brachytherapy) has been used to treat PC successfully for over a century. In particular, there is level-one evidence of the benefits of using brachytherapy to escalate the dose of radiotherapy compared with standard external beam radiotherapy approaches. However, the use of PC brachytherapy is declining, despite strong evidence for its improved cancer outcomes. A method using external beam radiotherapy known as virtual high-dose-rate brachytherapy boost (vHDRB) aims to noninvasively mimic a brachytherapy boost radiation dose plan. In this review, we consider the evidence supporting brachytherapy boosts for PC and the continuing evolution of vHDRB approaches, culminating in the current generation of clinical trials, which will help define the role of this emerging modality.

Seed lost to perineum from hydrogel spacer after brachytherapy for prostate cancer

Introduction

We describe a rare case of brachytherapy for prostate cancer in which a seed was lost from the perineum after a hydrogel injection.

Case presentation

A 71-year-old Japanese man was diagnosed with localized high-risk prostate cancer. Trimodality therapy with I-125 brachytherapy was selected, and combined androgen blockade therapy was initiated. Brachytherapy and hydrogel injection were performed 7 months after combined androgen blockade initiation; 6 months later, the patient visited our hospital with complaints of redness and bleeding in the perineum. Serous effusion and loss of a seed on the right side of the perineal anus were observed. Pelvic magnetic resonance imaging showed a tunnel like discharge of hydrogel from the dorsal prostate to the perineum. The fistula was incised, the seed was removed, and drainage was performed.

Conclusion

Appropriate diagnosis and treatment with careful follow-up are required in patients at high risk of infection after brachytherapy with hydrogel injection.

Comprehensive review of the use of hydrogel spacers prior to radiation therapy for prostate cancer

OBJECTIVES

To provide a comprehensive narrative review of the published data on the impact of hydrogel spacers on rectal dosimetry and toxicity and to outline the practicalities of inserting hydrogel spacers.

RESULTS

A growing body of evidence suggests that the administration of hydrogel spacers is safe and is associated with limited peri-operative morbidity. The impact on rectal dosimetry has been clearly established and use of hydrogel spacers is associated with reduced rectal morbidity. These results have been corroborated by several Phase II and III clinical trials and subsequent meta-analysis. There are several areas for future research, including the role of hydrogel spacers in prostate stereotactic beam radiotherapy and post-radiotherapy local recurrence.

CONCLUSIONS

Hydrogel spacers provide a low-morbidity method to potential reduce rectal toxicity after radiation therapy in men with prostate cancer. Data outlining sexual function and oncological outcomes are limited to date. Future studies, currently being conducted, may provide further clarification of the role of hydrogel spacers in prostate cancer management.

Safety of hydrogel spacers for rectal wall protection in patients with prostate cancer: A retrospective analysis of 200 consecutive cases

OBJECTIVE

To evaluate the safety and complications of hydrogel spacer implantation.

METHODS

This single-center historical cohort study retrospectively analyzed cases of hydrogel spacer implantation between October 2018 and March 2022. The survey items were the rates of possible hydrogel injection implementation, the success rate of hydrogel implantation including asymmetry, higher position, rectal wall infiltration, subcapsular injection, and other adverse events, and width created by the spacer. To investigate the learning curve, 1, 2, and 3 points were assigned to adverse event grades G1, G2, and G3, respectively. Spacer effectiveness obstruction, such as asymmetry was assigned 3 points. A Mann-Whitney U test was performed to assess statistically significant differences.

RESULTS

The study included a total of 200 patients with a median (range) age of 70 (44-85) years. In 10 (5%) patients, hydrogel injection implementation was not possible. Of 190 patients who underwent hydrogel spacer placement, 168 (88%) received a satisfactory placement. The median (range) width of hydrogel spacers was 13.1 (4.4-18.7) mm. Spacer asymmetry, higher position, rectal wall infiltration, and prostate subcapsular infiltration occurred in 7 (3.7%), 5 (2.6%), 12 (6.3%), and 1 (0.5%) patients, respectively. G1 and G3 adverse events occurred in 13 (7%) and 4 (2%) patients, respectively. Practitioner #1 who performed the highest number of procedures had significantly (p = 0.04) lower total scores in group B.

CONCLUSION

Spacer implantation yielded favorable outcomes with a high percentage of appropriate spacer implantation, and few major complications.

A novel hydrogel orthotopic injection model in moderately hypofractionated radiation therapy for prostate cancer: Adaptive degradation and durable imaging

Purpose

Moderately hypofractionated radiotherapy (MHRT) holds an important position in prostate cancer management. Existing hydrogel spacers can protect the rectum from radiation damage, but need improvement. We explored the application of a novel hydrogel in MHRT with adaptive degradation and durable imaging functions.

Methods and materials

The hydrogels were irradiated with 6MV x-ray to detect the radio-resistance property. Male SD rats (n=45) underwent hydrogel injection between the prostate and rectum. CT was used for investigating the novel spacer's degradation and imaging functions over three months. The hydrogel's radiation-attenuation properties and biocompatibility were further assessed.

Results

Hydrogel weight and volume remained stable for six weeks post-injection. After MHRT ended, the hydrogel showed accelerated degradation characteristics and remained in the body for at most three months. CT values of hydrogels exceeded 300 Hounsfield units (HU) throughout treatment, significantly higher than in surrounding normal tissues. A significant dose drop behind the hydrogel was observed post-implantation. Biocompatibility tests of hydrogel found it safe enough for living organisms.

Conclusions

The novel hydrogel application was fully adaptable to prostate cancer MHRT modalities, largely stable during treatment, rapidly degraded after radiotherapy ended, and consistently maintained superior imaging performance and biocompatibility. This novel spacer will be an effective tool in the era of hypofractionated radiotherapy.

Hyaluronic acid spacer in prostate cancer radiotherapy: dosimetric effects, spacer stability and long-term toxicity and PRO in a phase II study

BACKGROUND

Perirectal spacers may be beneficial to reduce rectal side effects from radiotherapy (RT). Here, we present the impact of a hyaluronic acid (HA) perirectal spacer on rectal dose as well as spacer stability, long-term gastrointestinal (GI) and genitourinary (GU) toxicity and patient-reported outcome (PRO).

METHODS

In this phase II study 81 patients with low- and intermediate-risk prostate cancer received transrectal injections with HA before external beam RT (78 Gy in 39 fractions). The HA spacer was evaluated with MRI four times; before (MR0) and after HA-injection (MR1), at the middle (MR2) and at the end (MR3) of RT. GI and GU toxicity was assessed by physician for up to five years according to the RTOG scale. PROs were collected using the Swedish National Prostate Cancer Registry and Prostate cancer symptom scale questionnaires.

RESULTS

There was a significant reduction in rectal V70% (54.6 Gy) and V90% (70.2 Gy) between MR0 and MR1, as well as between MR0 to MR2 and MR3. From MR1 to MR2/MR3, HA thickness decreased with 28%/32% and CTV-rectum space with 19%/17% in the middle level. The cumulative late grade ≥ 2 GI toxicity at 5 years was 5% and the proportion of PRO moderate or severe overall bowel problems at 5 years follow-up was 12%. Cumulative late grade ≥ 2 GU toxicity at 5 years was 12% and moderate or severe overall urinary problems at 5 years were 10%.

CONCLUSION

We show that the HA spacer reduced rectal dose and long-term toxicity.

Hyaluronic acid rectal spacer in EBRT: Usability, safety and symmetry related to user experience

OBJECTIVES

To report on the usability, safety, symmetry, and effectiveness of hyaluronic acid (HA) injected between the prostate and the rectum for patients undergoing treatment for prostate cancer with external beam radiotherapy (EBRT), and present a novel definition of rectal spacer symmetry that is reproducible and independent of patient anatomy.

PATIENTS AND METHODS

102 consecutive patients with clinical stage of T1c-3b prostate cancer underwent general anaesthesia for fiducial marker insertion and injection of HA into the perirectal space before EBRT. HA safety, symmetry, separation, and usability based on user experience were assessed.

RESULTS

HA insertion was completed with a 100% success rate independent of user experience, rated as 'easy' or 'very easy' in all cases. There were no postoperative complications reported. The mean (SD) recto-prostatic separation for all patients at the base, midgland and apex were 12 (±2) mm, 11 (±2) mm, and 9 (±1) mm respectively. The mean sagittal length of the implant was 43 (±5) mm. The implant was rated as symmetrical in 98% of cases. The mean rV70Gy was 1.6% (IQR 0.8-3.3%) for patients receiving 78-80Gy. The mean rV53Gy was 2.8% (IQR 1.2-4.8%) for patients receiving 60-62Gy. The median prostate size was 43.5 cc (IQR 32-57).

CONCLUSION

Injection of HA was able to achieve highly symmetrical recto-prostatic separation, with new users able to produce excellent separation, particularly at the apex, achieving similar dosimetry outcomes as competent and experienced users. HA is safe, easy to use, and significantly reduced mean rV70Gy and rV53Gy compared to non-spacer patients.

Focal injection of a radiopaque viscous spacer before focal brachytherapy as re-irradiation for locally recurrent prostate cancer

PURPOSE

Close vicinity of the target volume and a sensitive organ may prevent an effective radiotherapy/brachytherapy. A liquid hydrogel spacer cannot be placed well focally in specific small areas or fatty tissue. The purpose of this study was to report the injection technique and results of a radiopaque viscous hydrogel spacer.

METHODS

The radiopaque viscous spacer was applied focally using transrectal ultrasound guidance before focal brachytherapy in re-irradiated areas in two patients. The technical feasibility of the injection between the recurrence and the rectum / bladder, the resulting distance, visibility in different imaging modalities, stability within several months, dose distribution, toxicity and tumor control up to 18 months after treatment was analyzed.

RESULTS

After hydrodissection, the needle was moved from the base towards the apex during injection of each syringe, respectively. The viscous spacer could be successfully injected focally and resulted in a planned distancing of the target volume (right lobe and seminal vesicle area) and the rectum of at least 1 cm and additional distancing to the bladder of at least 5 mm. Both brachytherapy treatments were performed without relevant toxicities. The PSA nadirs indicated a satisfactory short-term response to the treatment.

CONCLUSIONS

The viscous hydrogel spacer can be injected focally at a specific prostate lobe or seminal vesicles. A viscous spacer remains stable within fatty tissue in any areas that are accessible by an ultrasound guided needle injection to create a distance between the high brachytherapy dose within the target and the organ at risk.

Laparoscopic spacer placement for bulky lymph node metastasis of cervical cancer: A case report

•

Spacers focus high-dose radiotherapy towards the target lesion.

•

Laparoscopic insertion of spacers allows for rapid initiation of radiotherapy.

•

Spacers may be applied to patients requiring multidisciplinary treatment beyond standard therapy.

Dose-escalated radiotherapy to 82 Gy for prostate cancer following insertion of a peri-rectal hydrogel spacer: 3-year outcomes from a phase II trial

BACKGROUND

Dose-escalation to above 80 Gy during external beam radiotherapy for localised prostate cancer leads to improved oncological outcomes but also substantially increased rectal toxicity. The aim of this study was to demonstrate the safety and efficacy of escalating the dose to 82 Gy following insertion of a peri-rectal hydrogel spacer (HS) prior to radiotherapy.

METHODS

This was a single arm, open-label, prospective study of men with localised prostate cancer who were prescribed a course of intensity modulated radiotherapy escalated to 82 Gy in 2 Gy fractions following insertion of the SpaceOAR™ HS (Boston Scientific, Marlborough, MA). Patients were prescribed a standard course of 78 Gy in 2 Gy fractions where rectal dose constraints could not be met for the 82 Gy plan. The co-primary endpoints were the rate of grade 3 gastrointestinal (GI) and genitourinary (GU) adverse events (CTCAE, v4), and patient-reported quality of life (QoL) (EORTC QLQ-C30 and PR25 modules), up to 37.5 months post-treatment.

RESULTS

Seventy patients received treatment on the study, with 64 (91.4%) receiving an 82 Gy treatment course. The median follow-up time post-treatment was 37.4 months. The rate of radiotherapy-related grade 3 GI and GU adverse events was 0% and 2.9%, respectively. There were 2 (2.9%) grade 3 adverse events related to insertion of the HS. Only small and transient declines in QoL were observed; there was no clinically or statistically significant decline in QoL beyond 13.5 months and up to 37.5 months post-treatment, compared to baseline. No late RTOG-defined grade ≥ 2 GI toxicity was observed, with no GI toxicity observed in any patient at 37.5 months post-treatment. Nine (12.9%) patients met criteria for biochemical failure within the follow-up period.

CONCLUSIONS

Dose-escalation to 82 Gy, facilitated by use of a hydrogel spacer, is safe and feasible, with minimal toxicity up to 37.5 months post-treatment when compared to rates of rectal toxicity in previous dose-escalation trials up to 80 Gy. Trials with longer follow-up of oncological and functional outcomes are required to robustly demonstrate a sustained widening of the therapeutic window. Trial registration Australian New Zealand Clinical Trials Registry, ACTRN12621000056897 , 22/01/2021. Retrospectively registered.

Delphi study to identify consensus on patient selection for hydrogel rectal spacer use during radiation therapy for prostate cancer in the UK

OBJECTIVES

To identify consensus on patient prioritisation for rectal hydrogel spacer use during radiation therapy for the treatment of prostate cancer in the UK.

DESIGN

Delphi study consisting of two rounds of online questionnaires, two virtual advisory board meetings and a final online questionnaire.

SETTING

Radical radiation therapy for localised and locally advanced prostate cancer in the UK.

PARTICIPANTS

Six leading clinical oncologists and one urologist from across the UK.

INTERVENTIONS

Rectal hydrogel spacer.

PRIMARY AND SECONDARY OUTCOME MEASURES

None reported.

RESULTS

The panel reached consensus on the importance of minimising toxicity for treatments with curative intent and that even low-grade toxicity-related adverse events can significantly impact quality of life. There was agreement that despite meeting rectal dose constraints, too many patients experience rectal toxicity and that rectal hydrogel spacers in eligible patients significantly reduces toxicity-related adverse events. However, as a consequence of funding limitations, patients need to be prioritised for spacer use. A higher benefit of spacers can be expected in patients on anticoagulation and in patients with diabetes or inflammatory bowel disease, but consensus could not be reached regarding patient groups expected to benefit less. While radiation therapy regimen is not a main factor determining prioritisation, higher benefit is expected in ultrahypofractionated regimens.

CONCLUSION

There is a strong and general agreement that all patients with prostate cancer undergoing radical radiation therapy have the potential to benefit from hydrogel spacers. Currently, not all patients who could potentially benefit can access hydrogel spacers, and access is unequal. Implementation of the consensus recommendations would likely help prioritise and equalise access to rectal spacers for patients in the UK.

The Swedish national guidelines on prostate cancer, part 1: early detection, diagnostics, staging, patient support and primary management of non-metastatic disease

OBJECTIVE

There is now an unprecedented amount of evidence to consider when revising prostate cancer guidelines. We believe that there is a value in publishing summaries of national clinical guidelines in English for others to read and comment on.

METHODS

This is part 1 of a summary of the Swedish prostate cancer guidelines that were published in June 2022. It covers the early detection, diagnostics, staging, patient support and management of the non-metastatic disease. Part 2 covers recurrence after local treatment and management of the metastatic disease.

RESULTS

The 2022 Swedish guidelines include several new recommendations: rectal iodine-povidone to reduce post-biopsy infections, external beam radiation with focal boost to the tumour, use of a pre-rectal spacer to reduce rectal side effects after external beam radiotherapy in some expert centres, 6 months' concomitant and adjuvant rather than neoadjuvant and concomitant hormonal treatment together with radiotherapy for unfavourable intermediate and high-risk disease, and adjuvant abiraterone plus prednisolone together with a GnRH agonist for a subgroup of men with very high-risk disease. The Swedish guidelines differ from the European by having more restrictive recommendations regarding genetic testing and pelvic lymph node dissection, the risk group classification, recommending ultra-hypofractionated (7 fractions) external radiotherapy for intermediate and selected high-risk cancers, by not recommending any hormonal treatment together with radiotherapy for favourable intermediate-risk disease, and by recommending bicalutamide monotherapy instead of a GnRH agonist for some patient groups.

CONCLUSIONS

The 2022 Swedish prostate cancer guidelines include several new recommendations and some that differ from the European guidelines.

Acute, Subchronic, and Chronic Complications of Radical Prostatectomy Versus Radiotherapy With Hormone Therapy in Older Adults With High-Risk Prostate Adenocarcinoma

Purpose

To compare acute, subchronic, and chronic complications between older patients with high-risk localized prostate cancer (HR-LPC) receiving radical prostatectomy (RP) and high-dose intensity-modulated radiotherapy (IMRT) combined with long-term hormone therapy (HT).

Patients and Methods

We recruited older patients (≥80 years) with HR-LPC from the Taiwan Cancer Registry database. After propensity score matching, logistic regression analysis was used to compare the acute, subchronic, and chronic complication rates between patients who underwent RP (the RP group) and high-dose IMRT combined with long-term HT (the IMRT+HT group).

Results

Benign prostatic hyperplasia (BPH) symptoms and urinary incontinence (UI) were the most common complications over 5 years (BPH symptoms: RP, 17.69%; IMRT+HT, 29.58%; UI: RP, 10.47%; IMRT+HT, 5.50%). Compared with the RP group, the IMRT+HT group had higher odds of BPH symptoms and lower odds of UI and hernia after the 5-year follow-up period. The impotence rates were significantly higher in the IMRT+HT group than in the RP group at 3 months and 1 year after treatment and became nonsignificant after 2 years. At 5 years after treatment, the IMRT+HT group had lower risks of UI (adjusted odds ratio [aOR], 0.50; 95% confidence interval [CI], 0.28–0.88) and hernia (aOR, 0.21; 95% CI, 0.11–0.82) and a higher risk of BPH symptoms (aOR, 4.15; 95% CI, 2.82–7.37) than the RP group.

Conclusion

IMRT+HT was associated with lower UI and hernia risks than RP. By contrast, RP was associated with fewer complications of BPH over the follow-up period and less impotence during the first year after treatment. Our findings provide important and valuable references for shared decision-making for optimal therapy selection among older men with HR-LPC.

Vaginal Sparing Radiotherapy Using IMPT and Daily Dilator Placement for Women with Anal Cancer

Sexual dysfunction is a common toxicity and detrimental for the quality of life of women treated with chemoradiotherapy for anal cancer. Sexual dysfunction occurs because the vagina is closely approximated to the anal canal and typically receives substantial doses of radiation. Strategies for mitigation have largely been focused on posttreatment therapy and symptom management. The use of daily vaginal dilator placement during radiotherapy to mitigate dose to the vagina has been previously explored with modest gains, while proton therapy is under active investigation for the treatment of anal cancer. Use of proton therapy for anal cancer reduces dose to some organs at risk but may inadvertently increase vaginal toxicity if the proton beam terminates in the vaginal tissue. Herein, we present the case histories of 2 women treated for squamous cell carcinoma of the anal canal with the novel combination of intensity-modulated proton therapy and daily vaginal dilator placement to maximally reduce dose to the vagina and protect it from areas of increased energy deposition at the end of the proton range.

Radiation therapy for prostate cancer: What's the best in 2021

Radiotherapy is highly involved in the management of prostate cancer. Its features and potential applications experienced a radical evolution over last decades, as they are associated to the continuous evolution of available technology and current oncological innovations. Some application of radiotherapy like brachytherapy have been recently enriched by innovative features and multidisciplinary dedications. In this report we aim to put some questions regarding the following issues regarding multiple aspects of modern application of radiation oncology: the current application of radiation oncology; the modern role of stereotactic body radiotherapy (SBRT) for both the management of primary lesions and for lymph-nodal recurrence; the management of the oligometastatic presentations; the role of brachytherapy; the aid played by the application of the organ at risk spacer (spacer OAR), fiducial markers, electromagnetic tracking systems and on-line Magnetic Resonance guided radiotherapy (MRgRT), and the role of the new opportunity represented by radiomic analysis.

Quantitative evaluation of volume change of perirectal hydrogel spacer by Dixon-based water-only images

Purpose

There are no detailed data on volume changes of SpaceOAR hydrogel spacer. The purpose of this study was to quantitatively evaluate the volume changes of SpaceOAR during radiation therapy for prostate cancer.

Materials

The volume of SpaceOAR in seven prostate cancer patients was quantitatively measured every two weeks by Dixon-based water-only MRI scans.

Results

The volume of SpaceOAR increased and remained increased for 11 weeks after placement in all cases. The day to reach the maximum volume was 49.9 +/- 9.2 (mean +/- standard deviation [SD]) days after placement. The maximum rate of increase in Space OAR volume was 20% +/- 9% (mean +/- SD).

Conclusions

The volume of SpaceOAR was shown to be greater than the initial volume for 11 weeks after placement, with an increase of up to 20%. Therefore, care should be taken when creating a radiation treatment planning and positioning a patient during radiation therapy.

SpaceOAR hydrogel spacer injection prior to stereotactic body radiation therapy for men with localized prostate cancer: A systematic review

BACKGROUND

Conventionally fractionated radiotherapy is a common treatment for men with localized prostate cancer. A growing consensus suggests that stereotactic body radiation therapy (SBRT) is similarly effective but less costly and more convenient for patients. The SpaceOAR hydrogel rectal spacer placed between the prostate and rectum reduces radiation-induced rectal injury in patients receiving conventionally fractionated radiotherapy, but spacer efficacy with SBRT is unclear. The purpose of this research was to assess the clinical utility of the hydrogel rectal spacer in men receiving SBRT for prostate cancer.

METHODS

We performed systematic searches of Medline, Embase, and the Cochrane Central Register of Controlled Trials for studies in men who received the SpaceOAR hydrogel spacer prior to SBRT (≥5.0 Gy fractions) for treatment of localized prostate center. Rectal irradiation results were compared to controls without spacer implant; all other outcomes were reported descriptively owing to lack of comparative data incuding perirectal separation distance, rectal irradiation on a dosimetric curve, gastrointestinal (GI) toxicity, and freedom from biochemical failure. GI toxicity was reported as the risk of a grade 2 or 3+ bowel complication in early (≤3 months) and late (>3 months) follow-up.

RESULTS

In 11 studies with 780 patients, SBRT protocols ranged from 7 to 10 Gy per fraction with total dose ranging from 19 to 45 Gy. Perirectal distance achieved with the rectal spacer ranged from 9.6 to 14.5 mm (median 10.8 mm). Compared to controls receiving no spacer, SpaceOAR placement reduced the radiation delivered to the rectum by 29% to 56% across a dosimetric profile curve. In early follow-up, grade 2 GI complications were reported in 7.0% of patients and no early grade 3+ GI complications were reported. In late follow-up, the corresponding rates were 2.3% for grade 2 and 0.3% for grade 3 GI toxicity. Over 16 months median follow-up, freedom from biochemical failure ranged from 96.4% to 100% (pooled mean 97.4%).

CONCLUSIONS

SpaceOAR hydrogel spacer placed between the prostate and rectum prior to SBRT is a promising preventative strategy that increases the distance between the prostate and rectum, reduces rectal radiation exposure, and may lower the risk of clinically important GI complications.

SAbR for High-Risk Prostate Cancer-A Prospective Multilevel MRI-Based Dose Escalation Trial

PURPOSE

Radiation dose intensification improves outcome in men with high-risk prostate cancer (HR-PCa). A prospective trial was conducted to determine safety, feasibility, and maximal tolerated dose of multilevel magnetic resonance imaging (MRI)-based 5-fraction SAbR in patients with HR-PCa.

METHODS AND MATERIALS

This phase I clinical trial enrolled patients with HR-PCa with grade group ≥4, prostate-specific antigen (PSA) ≥20 ng/mL, or radiographic ≥T3, and well-defined prostatic lesions on multiparametric MRI (mpMRI) into 4 dose-escalation cohorts. The initial cohort received 47.5 Gy to the prostate, 50 Gy to mpMRI-defined intraprostatic lesion(s), and 22.5 Gy to pelvic lymph nodes in 5 fractions. Radiation doses were escalated for pelvic nodes to 25 Gy and mpMRI lesion(s) to 52.5 Gy and then 55 Gy. Escalation was performed sequentially according to rule-based trial design with 7 to 15 patients per cohort and a 90-day observation period. All men received peri-rectal hydrogel spacer, intraprostatic fiducial placement, and 2 years of androgen deprivation. The primary endpoint was maximal tolerated dose according to a 90-day acute dose-limiting toxicity (DLT) rate <33%. DLT was defined as National Cancer Institute Common Toxicity Criteria for Adverse Events ≥grade 3 treatment-related toxicity. Secondary outcomes included acute and delayed gastrointestinal (GI)/genitourinary (GU) toxicity graded with Common Toxicity Criteria for Adverse Events.

RESULTS

Fifty-five of the 62 enrolled patients were included in the analysis. Dose was escalated through all 4 cohorts without observing any DLTs. Median overall follow-up was 18 months, with a median follow-up of 42, 24, 12, and 7.5 months for cohorts 1 to 4 respectively. Acute and late grade 2 GU toxicities were 25% and 20%, while GI were 13% and 7%, respectively. Late grade 3 GU and GI toxicities were 2% and 0%, respectively.

CONCLUSIONS

SAbR dose for HR-PCa was safely escalated with multilevel dose painting of 47.5 Gy to prostate, 55 Gy to mpMRI-defined intraprostatic lesions, and 25 Gy to pelvic nodal region in 5 fractions. Longer and ongoing follow-up will be required to assess late toxicity.