Intensity-modulated radiotherapy versus stereotactic body radiotherapy for prostate cancer (PACE-B): 2-year toxicity results from an open-label, randomised, phase 3, non-inferiority trial

Urethra-Sparing Prostate Cancer Stereotactic Body Radiation Therapy: Sexual Function and Radiation Dose to the Penile Bulb, the Crura, and the Internal Pudendal Arteries From a Randomized Phase 2 Trial

PURPOSE

Erectile dysfunction (ED) is a common side effect after prostate cancer stereotactic body radiation therapy (SBRT). We aimed to assess the correlation between the dose to the penile bulb (PB), internal pudendal arteries (IPA), and crura with the development of ED after ultrahypofractionation as part of a phase 2 clinical trial of urethra-sparing prostate SBRT.

METHODS AND MATERIALS

Among the 170 patients with localized prostate cancer from 9 centers included in the trial, 90 men with Common Terminology Criteria for Adverse Events version 4.03 grade 0 to 1 ED (ED-) at baseline treated with 36.25 Gy in 5 fractions were selected for the present analysis. Doses delivered to the PB, crura, and IPA were analyzed and correlated with grade 2 to 3 ED (ED+) development. The effect on quality of life, assessed by the European Organisation for Research and Treatment of Cancer (EORTC QLQ-PR25) questionnaire, was reported.

RESULTS

After a median follow-up of 6.5 years, 43% (n = 39) of the patients developed ED+, and 57% (n = 51) remained ED-. The dose delivered to the crura was significantly higher in ED+ patients than in ED- patients (7.7 vs 3.6 Gy [P = .014] for the Dmean and 18.5 vs 7.2 Gy [P = .015] for the D2%, respectively). No statistically significant difference between ED+ and ED- patients was observed for the dose delivered to the PB and IPA. The median ED+-free survival was worse in patients receiving a crura Dmean ≥ 4.7 versus < 4.7 Gy (51.5% vs 71.7%, P = .005) and a crura D2% > 12 versus ≤ 12 Gy (54.9% vs 68.9%, P = .015). No ED+-free survival differences were observed for doses delivered to the PB and IPA. Decline in EORTC QLQ-PR25 sexual functioning was significantly more pronounced in patients with higher doses to the crura.

CONCLUSIONS

By keeping a Dmean and D2% to crura below 4.7 and 12 Gy, respectively, the risk of developing ED+ after prostate SBRT may be significantly reduced.

Long-Term Quality-of-Life Outcomes After Prostate Radiation Therapy With or Without High-Dose-Rate Brachytherapy Boost: Post Hoc Analysis of TROG 03.04 RADAR

PURPOSE

Adding high-dose-rate brachytherapy (BT) boost to external beam radiation therapy (EBRT) improves biochemical control but may affect patient-reported quality of life (QOL). We sought to determine long-term QOL outcomes for EBRT+BT versus EBRT alone.

METHODS AND MATERIALS

This was a post hoc analysis of the Trans-Tasman Radiation Oncology Group 03.04 Randomized Androgen Deprivation and Radiotherapy (TROG 03.04 RADAR) trial. Only patients who received 74 Gy conventionally fractionated EBRT (n = 260) or 46 Gy conventionally fractionated EBRT plus 19.5 Gy in 3 fractions high-dose-rate BT boost (n = 237) were included in this analysis. The primary endpoint was patient-reported QOL measured using the European Organisation for Research and Treatment of Cancer QOL (EORTC QLQ-C30) and prostate-specific QOL module (EORTC QLQ-PR25) questionnaires. We evaluated temporal changes in QOL scores, rates of symptom resolution, and the proportion of men who had decrements from baseline of >2 × the threshold for minimal clinically important change (2 × MCIC) for each domain.

RESULTS

At 5, 17, and 29 months after radiation therapy, the EBRT+BT group had 2.5 times (95% confidence interval [CI], 1.4-4.2; P < .001), 2.9 times (95% CI, 1.7-4.9; P < .001), and 2.6 times (95% CI, 1.4-4.6; P = .002) greater odds of reporting 2 × MCIC in urinary QOL score compared with EBRT. There were no differences beyond 29 months. EBRT+BT led to a slower rate of urinary QOL symptom score resolution up to 17 months after radiation therapy compared with EBRT (P < .001) but not at later intervals. In contrast, at the end of the radiation therapy period and at 53 months after radiation therapy, the EBRT+BT group had 0.65 times (95% CI, 0.44-0.96; P = .03) and 0.51 times (95% CI, 0.32-0.79; P = .003) the odds of reporting 2 × MCIC in bowel QOL symptom scores compared with EBRT. There were no significant differences in the rate of bowel QOL score resolution. There were no significant differences in global health status or sexual activity scores between the 2 groups.

CONCLUSIONS

There were no persistent differences in patient-reported QOL measures between EBRT alone and EBRT+BT. BT boost does not appear to negatively affect long-term, patient-reported QOL.

Ultrahypofractionated Radiation Therapy for Prostate Cancer Including Seminal Vesicles in the Target Volume: A Treatment-planning Study Based on the HYPO-RT-PC Fractionation Schedule

Purpose

Ultrahypofractionated (UHF) radiation therapy (RT) has become a treatment alternative for patients with localized prostate cancer. In more advanced cases, seminal vesicles (SVs) are routinely included in the target volume. The Scandinavian HYPO-RT-PC trial, which compared 42.7 Gy in 7 fractions (fr) to conventional fractionation (CF), did not include SVs in the clinical target volume. The primary objective of the present work was to implement a ultrahypofractionated-simultaneous integrated boost (UHF-SIB) for prostate cancer RT, incorporating SVs into the target volume based on this fractionation schedule. A secondary objective was to analyze the unintentional dose coverage of SVs from state-of-the-art volumetric modulated arc therapy treatments to the prostate gland only.

Methods and Materials

Two different equieffective UHF-SIB treatment schedules to SVs were derived based on the CF clinical schedule (50.0 Gy/25 fr to elective SVs and 70.0 Gy/35 fr to verified SV-invasion (SVI)) using the linear quadric model with α/β = 2 Gy and 3 Gy. The dose to the prostate was 42.7 Gy/7 fr in both schedules, with 31.2 Gy/37.8 Gy (α/β = 2 Gy) and 32.7 Gy/40.1 Gy (α/β = 3 Gy) to elective SV/verified SVI. Volumetric modulated arc therapy plans to the proximal 10 mm and 20 mm were optimized, and dose-volume metrics for target volumes and organs at risk were evaluated.

Results

Dose metrics were overall lower for UHF-SIB compared with CF. QUANTEC-based volume criteria were 2% to 7% lower for the rectum and 2% to 4% lower for the bladder in the UHF-SIB. The D98% to elective SV was 7 to 12 Gy3 lower with UHF-SIB, and the corresponding data for verified SVI were approximately 2 to 3 Gy3. The SV(10 mm) V90%/(29.5 Gy) for prostate-only treatments (42.7 Gy) were as follows: median (IQR), 99% (87-100) and 78% (58-99) for the clinical target volume and planning target volume, respectively.

Conclusions

UHF RT based on the HYPO-RT-PC fractionation schedule, with a SIB technique, to the prostate and the base of the SV can be planned with lower doses (EQD2) to organs at risk, compared with CF. The unintentional dose to the proximal parts of SVs in prostate-only treatment can be substantial.

The expanding role of radiation oncology across the prostate cancer continuum

Radiotherapy is used in the treatment of prostate cancer in a variety of disease states with significant reliance on imaging to guide clinical decision-making and radiation delivery. In the definitive setting, the choice of radiotherapy treatment modality, dose, and fractionation for localized prostate cancer is determined by the patient's initial risk stratification and other clinical considerations. Radiation is also an option as salvage therapy in patients with locoregionally recurrent disease after prior definitive radiation or surgery. In recent years, the role of radiation has expanded for patients with metastatic disease, including prostate-directed radiotherapy in de novo low volume metastatic disease, metastasis-directed therapy for oligorecurrent disease, and palliative management of symptomatic metastases in the advanced setting. Here we review the expanding role of radiation in the treatment of prostate cancer in the definitive, locoregionally recurrent, and metastatic settings, as well as highlight the role of imaging in clinical reasoning, radiation planning, and treatment delivery.

Magnetic resonance image-guided adaptive radiotherapy enables safe CTV-to-PTV margin reduction in prostate cancer: a cine MRI motion study

Introduction

We aimed to establish if stereotactic body radiotherapy to the prostate can be delivered safely using reduced clinical target volume (CTV) to planning target volume (PTV) margins on the 1.5T MR-Linac (MRL) (Elekta, Stockholm, Sweden), in the absence of gating.

Methods

Cine images taken in 3 orthogonal planes during the delivery of prostate SBRT with 36.25 Gray (Gy) in 5 fractions on the MRL were analysed. Using the data from 20 patients, the percentage of radiotherapy (RT) delivery time where the prostate position moved beyond 1, 2, 3, 4 and 5 mm in the left-right (LR), superior-inferior (SI), anterior-posterior (AP) and any direction was calculated.

Results

The prostate moved less than 3 mm in any direction for 90% of the monitoring period in 95% of patients. On a per-fraction basis, 93% of fractions displayed motion in all directions within 3 mm for 90% of the fraction delivery time. Recurring motion patterns were observed showing that the prostate moved with shallow drift (most common), transient excursions and persistent excursions during treatment.

Conclusion

A 3 mm CTV-PTV margin is safe to use for the treatment of 5 fraction prostate SBRT on the MRL, without gating. In the context of gating this work suggests that treatment time will not be extensively lengthened when an appropriate gating window is applied.

Neutrophil-to-lymphocyte ratio for the prediction of soft tissue sarcomas response to pre-operative radiation therapy

PURPOSE/OBJECTIVE

This study aims to assess the prognostic value of the neutrophil-to-lymphocyte ratio (NLR) in soft tissue sarcomas (STS) treated with pre-operative hypofractionated radiotherapy (HFRT).

MATERIALS/METHODS

This retrospective analysis included patients treated with pre-operative HFRT of 30 Gy in 5 fractions between 2016 and 2023. Clinical, demographic, and complete blood count (CBC) data were collected. NLR was calculated by dividing the absolute neutrophil count by the absolute lymphocyte count. Only patients with CBCs conducted within 6 months after radiotherapy were included. Cox proportional-hazard regression models were used to assess the impact of NLR and different variables on outcomes. Kaplan Meier were used to illustrate survival curves. A p-value < 0.05 was considered significant, and 95 % confidence intervals (CI) were employed.

RESULTS

A total of 40 patients received HFRT and had CBCs within 6 months after radiotherapy. There were 17 (42.5 %) females and 23 (57.5 %) males with a mean age of 66 years. The mean largest tumor size dimension was 7.1 cm, and the mean NLR post-RT was 5.3. The most frequent histological subtypes were myxofibrosarcoma (17.5 %), pleomorphic spindle cell sarcoma (10 %), leiomyosarcoma (7.5 %), and myxoid liposarcoma (5 %). The median follow-up period was 15.4 months. From all patients, 14 patients had disease progression, 12 metastatic disease and 3 died of disease. Multivariable Cox proportional-hazards regression analysis displayed that a higher post-RT NLR was associated with worse disease-free survival (DFS) (HR: 1.303 [1.098-1.548], p = 0.003), and distant metastasis-free survival (DMFS) (HR: 1.38 [1.115-1.710], p = 0.003). Moreover, post-NLR ≥ 4 as a single variable was associated with worse DFS, DMFS, but not worse local recurrence or overall survival.

CONCLUSION

This study is the first to evaluate NLR as a prognostic biomarker in STS patients treated with pre-operative radiotherapy. A higher NLR after pre-operative radiotherapy was associated with increased disease progression.

Photon vs proton hypofractionation in prostate cancer: A systematic review and meta-analysis

BACKGROUND

High-level evidence on hypofractionated proton therapy (PT) for localized and locally advanced prostate cancer (PCa) patients is currently missing. The aim of this study is to provide a systematic literature review to compare the toxicity and effectiveness of curative radiotherapy with photon therapy (XRT) or PT in PCa.

METHODS

PubMed, Embase, and the Cochrane Library databases were systematically searched up to April 2022. Men with a diagnosis of PCa who underwent curative hypofractionated RT treatment (PT or XRT) were included. Risk of grade (G) ≥ 2 acute and late genitourinary (GU) OR gastrointestinal (GI) toxicity were the primary outcomes of interest. Secondary outcomes were five-year biochemical relapse-free survival (b-RFS), clinical relapse-free, distant metastasis-free, and prostate cancer-specific survival. Heterogeneity between study-specific estimates was assessed using Chi-square statistics and measured with the I2 index (heterogeneity measure across studies).

RESULTS

A total of 230 studies matched inclusion criteria and, due to overlapped populations, 160 were included in the present analysis. Significant lower rates of G ≥ 2 acute GI incidence (2 % vs 7 %) and improved 5-year biochemical relapse-free survival (95 % vs 91 %) were observed in the PT arm compared to XRT. PT benefits in 5-year biochemical relapse-free survival were maintained for the moderate hypofractionated arm (p-value 0.0122) and among patients in intermediate and low-risk classes (p-values < 0.0001 and 0.0368, respectively). No statistically relevant differences were found for the other considered outcomes.

CONCLUSION

The present study supports that PT is safe and effective for localized PCa treatment, however, more data from RCTs are needed to draw solid evidence in this setting and further effort must be made to identify the patient subgroups that could benefit the most from PT.

Sexual Structure Sparing for Prostate Cancer Radiotherapy: A Systematic Review

CONTEXT

Erectile dysfunction represents a major side effect of prostate cancer (PCa) treatment, negatively impacting men's quality of life. While radiation therapy (RT) advances have enabled the mitigation of both genitourinary and gastrointestinal toxicities, no significant improvement has been showed in sexual quality of life over time.

OBJECTIVE

The primary aim of this review was to assess sexual structures' dose-volume parameters associated with the onset of erectile dysfunction.

EVIDENCE ACQUISITION

We searched the PubMed database and ClinicalTrials.gov until January 4, 2023. Studies reporting the impact of the dose delivered to sexual structures on sexual function or the feasibility of innovative sexual structure-sparing approaches were deemed eligible.

EVIDENCE SYNTHESIS

Sexual-sparing strategies have involved four sexual organs. The mean penile bulb doses exceeding 20 Gy are predictive of erectile dysfunction in modern PCa RT trial. Maintaining a D100% of ≤36 Gy on the internal pudendal arteries showed preservation of erectile function in 88% of patients at 5 yr. Neurovascular bundle sparing appears feasible with magnetic resonance-guided radiation therapy, yet its clinical impact remains unanswered. Doses delivered to the testicles during PCa RT usually remain <2 Gy and generate a decrease in testosterone levels ranging from -4.6% to -17%, unlikely to have any clinical impact.

CONCLUSIONS

Current data highlight the technical feasibility of sexual sparing for PCa RT. The proportion of erectile dysfunction attributable to the dose delivered to sexual structures is still largely unknown. While the ability to maintain sexual function over time is impacted by factors such as age or comorbidities, only selected patients are likely to benefit from sexual-sparing RT.

PATIENT SUMMARY

Technical advances in radiation therapy (RT) made it possible to significantly lower the dose delivered to sexual structures. While sexual function is known to decline with age, the preservation of sexual structures for prostate cancer RT is likely to be beneficial only in selected patients.

Conditional Risk and Predictive Factors Associated with Late Toxicity for Prostate Cancer Patients Treated with External Beam Radiotherapy Alone on Randomized Trial RTOG 0126

PURPOSE

The objective of this study was to characterize the conditional risk of developing a grade 2+ urinary or gastrointestinal toxicity for patients treated with external beam radiotherapy on RTOG 0126. A secondary objective was to analyze baseline patient and treatment characteristics and determine their relevance in predicting toxicity both at the time of trial enrollment and later points of follow up.

METHODS AND MATERIALS

1,532 patients with localized prostate cancer were enrolled between March 2002 and August 2008, of whom 1,499 were eligible and included in data analysis with a median follow up of 8.4 years (range 0.02-13). Patients were treated with either 3DCRT or IMRT according to institutional practice without the addition of androgen deprivation and randomized to receive either standard dose radiotherapy of 70.2 Gy or dose escalated radiotherapy of 79.2 Gy of radiotherapy to the prostate only with standard fractionation. UVA and MVA analyses were determine if initial factors were predictive of late toxicity at time of treatment and at later timepoints.

RESULTS

As patients proceed further from completion of radiotherapy without the development of toxicity, the subsequent risk of both grade 2+ GU and GI toxicity decreased with time. At time of enrollment the risk of developing a grade 2+ toxicity over the next 5 years was 9.57 and 17.89% respectively. After five years of toxicity free survival, the risk of developing a grade 2+ GU or GI toxicity in the subsequent five years was 3.02% and 1.54% respectively. Baseline treatment and patient related factors predicted late toxicity both at trial enrollment and after two years of toxicity free survivorship. Baseline urinary dysfunction and dose escalated radiotherapy were associated with increased late GU toxicity. Acute GI toxicity and dose escalated radiotherapy were associated with increased risk of late GI toxicity. Treatment with IMRT was associated with reduced risk of either toxicity.

CONCLUSIONS

The conditional risk of grade 2+ toxicities decrease as patients proceed further from treatment with most toxicities occurring in the first few years after treatment completion. Baseline patient and treatment characteristics remain relevant at both enrollment and later time points.

Stereotactic Body Radiotherapy (SBRT) to Localised Prostate Cancer in the Era of MRI-Guided Adaptive Radiotherapy: Doses Delivered in the HERMES Trial Comparing Two- and Five-Fraction Treatments

HERMES is a phase II trial of MRI-guided daily-adaptive radiotherapy (MRIgART) randomising men with localised prostate cancer to either 2-fractions of SBRT with a boost to the tumour or 5-fraction SBRT. In the context of this highly innovative regime the dose delivered must be carefully considered. The first ten patients recruited to HERMES were analysed in order to establish the dose received by the targets and organs at risk (OARS) in the context of intrafraction motion. A regression analysis was performed to measure how the volume of air within the rectum might further impact rectal dose secondary to the electron return effect (ERE). One hundred percent of CTV target objectives were achieved on the MRI taken prior to beam-on-time. The post-delivery MRI showed that high-dose CTV coverage was achieved in 90% of sub-fractions (each fraction is delivered in two sub-fractions) in the 2-fraction cohort and in 88% of fractions the 5-fraction cohort. Rectal D1 cm3 was the most exceeded constraint; three patients exceeded the D1 cm3 < 20.8 Gy in the 2-fraction cohort and one patient exceeded the D1 cm3 < 36 Gy in the 5-fraction cohort. The volume of rectal gas within 1 cm of the prostate was directly proportional to the increase in rectal D1 cm3, with a strong (R = 0.69) and very strong (R = 0.90) correlation in the 2-fraction and 5-fraction cohort respectively. Dose delivery specified in HERMES is feasible, although for some patients delivered doses to both target and OARs may vary from those planned.

Meta-Analysis of 5-Fraction Preoperative Radiotherapy for Soft Tissue Sarcoma

OBJECTIVES

Studies investigating preoperative 5-fraction radiation therapy (RT) for soft tissue sarcoma (STS) are limited. We performed a meta-analysis to determine the efficacy and safety of this treatment paradigm.

METHODS

This study-level meta-analysis was conducted using Bayesian methods. Statistical estimation for risk of outcome rates was conducted by posterior mean and 95% highest posterior density (HPD) intervals. Studies with 2-year local control (LC) and description of major wound complications (MWC) per the CAN-NCIC-SR2 study were included and served as the primary endpoints. Secondary endpoints included rates of acute and late toxicity. A total of 10 studies were identified and 7 met the inclusion criteria. Subgroup analyses were performed for ≥30 Gy vs <30 Gy.

RESULTS

A total of 209 patients from 7 studies were included. Five studies used ≥30 Gy (n=144), and 2 studies <30 Gy (n=64). Median follow-up was 29 months (range: 21 to 57 mo). Primary tumor location was lower extremity in 68% and upper extremity in 22%. Most tumors were intermediate or high grade (95%, 160/169), and 50% (79/158) were >10 cm. The two-year LC for the entire cohort was 96.9%, and the rate of MWC was 30.6%. There was a trend toward improved LC with ≥ 30 Gy (95% HPD: 0.95 to 0.99 vs 0.84 to 0.99). There was no difference in MWC (95% HPD: 0.18 to 0.42 vs 0.17 to 0.55) or late toxicity between the groups.

CONCLUSION

Preoperative 5-fraction RT for STS demonstrates excellent 2-year LC with MWC and toxicity similar to standard fractionation preoperative RT. Multi-institutional trials with a universal RT protocol are warranted.

Online Adaptive MR-Guided Ultrahypofractionated Radiotherapy of Prostate Cancer on a 1.5 T MR-Linac: Clinical Experience and Prospective Evaluation

The use of hypofractionated radiotherapy in prostate cancer has been increasingly evaluated, whereas accumulated evidence demonstrates comparable oncologic outcomes and toxicity rates compared to normofractionated radiotherapy. In this prospective study, we evaluate all patients with intermediate-risk prostate cancer treated with ultrahypofractionated (UHF) MRI-guided radiotherapy on a 1.5 T MR-Linac within our department and report on workflow and feasibility, as well as physician-recorded and patient-reported longitudinal toxicity. A total of 23 patients with intermediate-risk prostate cancer treated on the 1.5 T MR-Linac with a dose of 42.7 Gy in seven fractions (seven MV step-and-shoot IMRT) were evaluated within the MRL-01 study (NCT04172753). The duration of each treatment step, choice of workflow (adapt to shape-ATS or adapt to position-ATP) and technical and/or patient-sided treatment failure were recorded for each fraction and patient. Acute and late toxicity were scored according to RTOG and CTC V4.0, as well as the use of patient-reported questionnaires. The median follow-up was 12.4 months. All patients completed the planned treatment. The mean duration of a treatment session was 38.2 min. In total, 165 radiotherapy fractions were delivered. ATS was performed in 150 fractions, 5 fractions were delivered using ATP, and 10 fractions were delivered using both ATS and ATP workflows. Severe acute bother (G3+) regarding IPS-score was reported in five patients (23%) at the end of radiotherapy. However, this tended to normalize and no G3+ IPS-score was observed later at any point during follow-up. Furthermore, no other severe genitourinary (GU) or gastrointestinal (GI) acute or late toxicity was observed. One-year biochemical-free recurrence survival was 100%. We report the excellent feasibility of UHF MR-guided radiotherapy for intermediate-risk prostate cancer patients and acceptable toxicity rates in our preliminary study. Randomized controlled studies with long-term follow-up are warranted to detect possible advantages over current state-of-the-art RT techniques.

Navigating the evolving diagnostic and therapeutic landscape of low- and intermediate-risk prostate cancer

ABSTRACT

In this nonsystematic review of the literature, we explored the changing landscape of detection and treatment of low- and intermediate-risk prostate cancer (PCa). Through emphasizing improved cancer assessment with histology classification and genomics, we investigated key developments in PCa detection and risk stratification. The pivotal role of prostate magnetic resonance imaging (MRI) in the novel diagnostic pathway is examined, alongside the benefits and drawbacks of MRI-targeted biopsies for detection and tumor characterization. We also delved into treatment options, particularly active surveillance for intermediate-risk PCa. Outcomes are compared between intermediate- and low-risk patients, offering insights into tailored management. Surgical techniques, including Retzius-sparing surgery, precision prostatectomy, and partial prostatectomy for anterior cancer, are appraised. Each technique has the potential to enhance outcomes and minimize complications. Advancements in technology and radiobiology, including computed tomography (CT)/MRI imaging and positron emission tomography (PET) fusion, allow for precise dose adjustment and daily target monitoring with imaging-guided radiotherapy, opening new ways of tailoring patients' treatments. Finally, experimental therapeutic approaches such as focal therapy open new treatment frontiers, although they create new needs in tumor identification and tracking during and after the procedure.

Stereotactic Body Radiation Therapy for the Curative Treatment of Prostate Cancer in Ultralarge (≥100 cc) Glands

PURPOSE

Historically, toxicity concerns have existed in patients with large prostate glands treated with radiation therapy, particularly brachytherapy. There are questions whether this risk extends to stereotactic body radiation therapy (SBRT). In this retrospective review, we examine clinical outcomes of patients with prostate glands ≥100 cc treated curatively with SBRT.

METHODS AND MATERIALS

We retrospectively analyzed a large institutional database to identify patients with histologically confirmed localized prostate cancer in glands ≥100 cc, who were treated with definitive-robotic SBRT. Prostate volume (PV) was determined by treatment planning magnetic resonance imaging. Toxicity was measured using Common Terminology Criteria for Adverse Events, version 5.0. Many patients received the Expanded Prostate Cancer Index Composite Quality of Life questionnaires. Minimum follow-up (FU) was 2 years.

RESULTS

Seventy-one patients were identified with PV ≥100 cc. Most had grade group (GG) 1 or 2 (41% and 37%, respectively) disease. All patients received a total dose of 3500 to 3625 cGy in 5 fractions. A minority (27%) received androgen deprivation therapy (ADT), which was used for gland size downsizing in only 10% of cases. Nearly half (45%) were taking GU medications for urinary dysfunction before RT. Median toxicity FU was 4.0 years. Two-year rates of grade 1+ genitourinary (GU), grade 1+ gastrointestinal (GI), and grade 2+ GU toxicity were 43.5%, 15.9%, and 30.4%, respectively. Total grade 3 GU toxicities were very limited (2.8%). There were no grade 3 GI toxicities. On logistic regression analysis, pretreatment use of GU medications was significantly associated with increased rate of grade 2+ GU toxicity (odds ratio, 3.19; P = .024). Furthermore, PV (analyzed as a continuous variable) did not have an effect on toxicity, quality of life, or oncologic outcomes.

CONCLUSIONS

With early FU, ultra large prostate glands do not portend increased risk of high-grade toxicity after SBRT but likely carry an elevated risk of low-grade GU toxicity.

Stereotactic ultrahypofractionated MR-guided radiotherapy for localized prostate cancer - Acute toxicity and patient-reported outcomes in the prospective, multicenter SMILE phase II trial

Background

Due to superior image quality and daily adaptive planning, MR-guided stereotactic body radiation therapy (MRgSBRT) has the potential to further widen the therapeutic window in radiotherapy of localized prostate cancer. This study reports on acute toxicity rates and patient-reported outcomes after MR-guided adaptive ultrahypofractionated radiotherapy for localized prostate cancer within the prospective, multicenter phase II SMILE trial.

Materials and methods

A total of 69 patients with localized prostate cancer underwent MRgSBRT with daily online plan adaptation. Inclusion criteria comprised a tumor stage ≤ T3a, serum PSA value ≤ 20 ng/ml, ISUP Grade group ≤ 4. A dose of 37.5 Gy was prescribed to the PTV in five fractions on alternating days with an optional simultaneous boost of 40 Gy to the dominant intraprostatic lesion defined by multiparametric MRI. Acute genitourinary (GU-) and gastrointestinal (GI-) toxicity, as defined by CTCAE v. 5.0 and RTOG as well as patient-reported outcomes according to EORTC QLQ-C30 and -PR25 scores were analyzed at completion of radiotherapy, 6 and 12 weeks after radiotherapy and compared to baseline symptoms.

Results

There were no toxicity-related treatment discontinuations. At the 12-week follow-up visit, no grade 3 + toxicities were reported according to CTCAE. Up until the 12-week visit, in total 16 patients (23 %) experienced a grade 2 GU or GI toxicity. Toxicity rates peaked at the end of radiation therapy and subsided within the 12-week follow-up period. At the 12-week follow-up visit, no residual grade 2 GU toxicities were reported and 1 patient (1 %) had residual grade 2 enteritic symptoms. With exception to a significant improvement in the emotional functioning score following MRgSBRT, no clinically meaningful changes in the global health status nor in relevant subscores were reported.

Conclusion

Daily online-adaptive MRgSBRT for localized prostate cancer resulted in an excellent overall toxicity profile without any major negative impact on quality of life.

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.

Late Toxicity of Prostate Ultrahypofractionated Radiation Therapy Compared With Moderate Hypofractionation in a Randomized Trial

PURPOSE

We report late toxicity, quality of life (QOL), and urinary symptom score with prostate cancer radiation therapy in a randomized trial comparing moderate hypofractionation and ultrahypofrationation.

METHODS AND MATERIALS

Patients with intermediate and high-risk prostate cancer were randomized to either Arm 1 (70 Gy/28 fractions) or Arm 2 (36.25 Gy/5 weekly fractions). Late toxicity was evaluated using the Common Terminology Criteria for Adverse Events and Radiation Therapy Oncology Group/Subjective, Objective, Management, Analytical scales. QOL was assessed with the Expanded Prostate Inventory Composite-26 Short Form and urinary function with the International Prostate Symptom Score.

RESULTS

Eighty participants were randomized. Two from Arm 1 withdrew, leaving 36 patients in Arm 1 and 42 in Arm 2. There were no significant differences in baseline characteristics, except for worse International Prostate Symptom Score in Arm 2. No difference was observed in freedom from grade 3 or worse toxicity between treatments (P = .921), with only a single grade 3 event in each arm. There was no significant difference in freedom from grade 2 or worse toxicity (P = .280). No difference was observed in freedom from grade 2 or worse genitorurinary toxicity, with cumulative probabilities of 69.0% and 87.0% at 5 years for Arms 1 and 2, respectively (0.132). No difference was observed in freedom from grade 2 or worse gastrointestinal toxicity, with cumulative probabilities of 74.0% in Arm 1 and 80.0% in Arm 2 (P = .430). There were no significant differences in Expanded Prostate Inventory Composite-26 Short Form QOL between arms.

CONCLUSIONS

Ultrahypofrationation, delivered weekly, is well tolerated with no significant differences in freedom from late toxicity compared with moderate hypofractionation.

Dose-response of localized renal cell carcinoma after stereotactic body radiation therapy: A meta-analysis

BACKGROUND

Stereotactic ablative radiation therapy (SBRT) is an emerging treatment option for primary renal cell carcinoma (RCC), particularly in patients who are unsuitable for surgery. The aim of this review is to assess the effect of increasing the biologically equivalent dose (BED) via various radiation fractionation regimens on clinical outcomes.

METHODS

A literature search was conducted in PubMed (Medline), EMBASE, and the Cochrane Library for studies published up to October 2023. Studies reporting on patients with localized RCC receiving SBRT were included to determine its effectiveness on local control, progression-free survival, and overall survival. A random effects model was used to meta-regress clinical outcomes relative to the BED for each study and heterogeneity was assessed by I2.

RESULTS

A total of 724 patients with RCC from 22 studies were included, with a mean age of 72.7 years (range: 44.0-81.0). Local control was excellent with an estimate of 99 % (95 %CI: 97-100 %, I2 = 19 %), 98 % (95 %CI: 96-99 %, I2 = 8 %), and 94 % (95 %CI: 90-97 %, I2 = 11 %) at one year, two years, and five years respectively. No definitive association between increasing BED and local control, progression-free survival and overall survival was observed. No publication bias was observed.

CONCLUSIONS

A significant dose response relationship between oncological outcomes and was not identified, and excellent local control outcomes were observed at the full range of doses. Until new evidence points otherwise, we support current recommendations against routine dose escalation beyond 25-26 Gy in one fraction or 42-48 Gy in three fractions, and to consider de-escalation or compromising target coverage if required to achieve safe organ at risk doses.

MRI-guided radiotherapy in twenty fractions for localised prostate cancer; results from the MOMENTUM study

Background and purpose

MRI-guided radiotherapy (MRIgRT) offers multiple potential advantages over CT-guidance. This study examines the potential clinical benefits of MRIgRT for men with localised prostate cancer, in the setting of moderately hypofractionated radiotherapy. We evaluate two-year toxicity outcomes, early biochemical response and patient-reported outcomes (PRO), using data obtained from a multicentre international registry study, for the first group of patients with prostate cancer who underwent treatment on a 1.5 T MR-Linac.

Materials and methods

Patients who were enrolled within the MOMENTUM study and received radical treatment with 60 Gy in 20 fractions were identified. PSA levels and CTCAE version 5.0 toxicity data were measured at follow-up visits. Those patients who consented to PRO data collection also completed EQ-5D-5L, EORTC QLQ-C30 and EORTC QLQ-PR25 questionnaires.

Results

Between November 2018 and June 2022, 146 patients who had MRIgRT for localised prostate cancer on the 1.5 T MR-Linac were eligible for this study. Grade 2 and worse gastro-intestinal (GI) toxicity was reported in 3 % of patients at three months whilst grade 2 and worse genitourinary (GU) toxicity was 7 % at three months. There was a significant decrease in the median PSA at 12 months. The results from both the EQ-5D-5L data and EORTC global health status scale indicate a decline in the quality of life (QoL) during the first six months. The mean change in score for the EORTC scale showed a decrease of 11.4 points, which is considered clinically important. QoL improved back to baseline by 24 months. Worsening of hormonal symptoms in the first six months was reported with a return to baseline by 24 months and sexual activity in all men worsened in the first three months and returned to baseline at 12 months.

Conclusion

This study establishes the feasibility of online-MRIgRT for localised prostate on a 1.5 T MR-Linac with low rates of toxicity, similar to that published in the literature. However, the clinical benefits of MRIgRT over conventional radiotherapy in the setting of moderate hypofractionation is not evident. Further research will focus on the delivery of ultrahypofractionated regimens, where the potential advantages of MRIgRT for prostate cancer may become more discernible.

ONE SHOT - single shot radiotherapy for localized prostate cancer: 18-month results of a single arm, multicenter phase I/II trial

PURPOSE

To assess in a prospective, multicenter, single-arm phase I/II study the early safety and efficacy profile of single fraction urethra-sparing stereotactic body radiotherapy (SBRT) for men with localized prostate cancer.

MATERIAL AND METHODS

Patients with low- and intermediate-risk localized prostate cancer without significant tumor in the transitional zone were recruited. A single-fraction of 19 Gy was delivered to the prostate, with 17 Gy dose-reduction to the urethra. Intrafraction motion was monitored using intraprostatic electromagnetic transponders with intra-fraction correction of displacements exceeding 3 mm. Genitourinary (GU), gastrointestinal (GI), and sexual toxicity during the first 18 months were evaluated using the CTCAE v4.0 grading scale. Quality of life was assessed using the International Prostate Symptom Score, the Expanded Prostate Cancer Index composite 26 score, and the International Index of Erectile Function score.

RESULTS

Among the 45 patients recruited in 5 centers between 2017 and 2022, 43 received the single fraction without protocol deviations, and 34 had a minimal follow-up of 18 months. The worst GU toxicity was observed at day-5 after SBRT (42.5 % and 20 % with grade 1 and 2, respectively), returning to baseline at week-12 and month-6 (<3% with grade 2), with a 12 % grade 2 flare at month 18. Gl toxicity was mild in the acute phase, with no grade ≥ 2 events (12 % grade 1 at month 6). Grade-3 proctitis was observed in one patient at month 12, with < 3 % grade 2 toxicity at month 18. Mean GU and GI bother scores showed a decline at day 5, a complete recovery at month 6, and a flare between month 12 and 18. Mean PSA dropped from 6.2 ng/ml to 1.2 ng/ml at month 18 and 0.7 ng/ml at month 24. After a median follow-up time of 26 months, 3 biochemical failures (7 %) were observed at month 17, 21 and 30.

CONCLUSIONS

In this multicenter phase I/II trial, we demonstrated that a 19 Gy single-fraction urethra-sparing SBRT is feasible and associated with an acceptable toxicity rate, mostly returning to the baseline at week-12 and with a symptoms flare between months 12 and 18. Longer follow-up is needed to assess the potential long-term adverse effects and the disease control efficacy.

Brand D, Lee E, Loblaw A, Tolan S, van As N, Tree AC. Developing and validating a simple urethra surrogate model to facilitate dosimetric analysis to predict genitourinary toxicity

Purpose

The urethra is a critical structure in prostate radiotherapy planning; however, it is impossible to visualise on CT. We developed a surrogate urethra model (SUM) for CT-only planning workflow and tested its geometric and dosimetric performance against the MRI-delineated urethra (MDU).

Methods

The SUM was compared against 34 different MDUs (within the treatment PTV) in patients treated with 36.25Gy (PTV)/40Gy (CTV) in 5 fractions as part of the PACE-B trial. To assess the surrogate's geometric performance, the Dice similarity coefficient (DSC), Hausdorff distance (HD), mean distance to agreement (MDTA) and the percentage of MDU outside the surrogate (UOS) were calculated. To evaluate the dosimetric performance, a paired t-test was used to calculate the mean of differences between the MDU and SUM for the D99, D98, D50, D2 and D1. The D(n) is the dose (Gy) to n% of the urethra.

Results

The median results showed low agreement on DSC (0.32; IQR 0.21-0.41), but low distance to agreement, as would be expected for a small structure (HD 8.4mm (IQR 7.1-10.1mm), MDTA 2.4mm (IQR, 2.2mm-3.2mm)). The UOS was 30% (IQR, 18-54%), indicating nearly a third of the urethra lay outside of the surrogate. However, when comparing urethral dose between the MDU and SUM, the mean of differences for D99, D98 and D95 were 0.12Gy (p=0.57), 0.09Gy (p=0.61), and 0.11Gy (p=0.46) respectively. The mean of differences between the D50, D2 and D1 were 0.08Gy (p=0.04), 0.09Gy (p=0.02) and 0.1Gy (p=0.01) respectively, indicating good dosimetric agreement between MDU and SUM.

Conclusion

While there were geometric differences between the MDU and SUM, there was no clinically significant difference between urethral dose-volume parameters. This surrogate model could be validated in a larger cohort and then used to estimate the urethral dose on CT planning scans in those without an MRI planning scan or urinary catheter.

Feasibility and Acute Toxicity of Hypo-Fractionated Radiotherapy on 0.35T MR-LINAC: The First Prospective Study in Spain

This observational, descriptive, longitudinal, and prospective basket-type study (Registry #5289) prospectively evaluated the feasibility and acute toxicity of hypo-fractionated radiotherapy on the first 0.35T MR-LINAC in Spain. A total of 37 patients were included between August and December 2023, primarily with prostate tumors (59.46%), followed by pancreatic tumors (32.44%). Treatment regimens typically involved extreme hypo-fractionated radiotherapy, with precise dose delivery verified through quality assurance measures. Acute toxicity assessment at treatment completion revealed manageable cystitis, with one case persisting at the three-month follow-up. Gastrointestinal toxicity was minimal. For pancreatic tumors, daily adaptation of organ-at-risk (OAR) and gross tumor volume (GTV) was practiced, with median doses to OAR within acceptable limits. Three patients experienced gastrointestinal toxicity, mainly nausea. Overall, the study demonstrates the feasibility and safety of extreme hypo-fractionated radiotherapy on a 0.35T MR-LINAC, especially for challenging anatomical sites like prostate and pancreatic tumors. These findings support the feasibility of MR-LINAC-based radiotherapy in delivering precise treatments with minimal toxicity, highlighting its potential for optimizing cancer treatment strategies.

EAU-EANM-ESTRO-ESUR-ISUP-SIOG Guidelines on Prostate Cancer-2024 Update. Part I: Screening, Diagnosis, and Local Treatment with Curative Intent

BACKGROUND AND OBJECTIVE

The European Association of Urology (EAU)-European Association of Nuclear Medicine (EANM)-European Society for Radiotherapy and Oncology (ESTRO)-European Society of Urogenital Radiology (ESUR)-International Society of Urological Pathology (ISUP)-International Society of Geriatric Oncology (SIOG) guidelines provide recommendations for the management of clinically localised prostate cancer (PCa). This paper aims to present a summary of the 2024 version of the EAU-EANM-ESTRO-ESUR-ISUP-SIOG guidelines on the screening, diagnosis, and treatment of clinically localised PCa.

METHODS

The panel performed a literature review of all new data published in English, covering the time frame between May 2020 and 2023. The guidelines were updated, and a strength rating for each recommendation was added based on a systematic review of the evidence.

KEY FINDINGS AND LIMITATIONS

A risk-adapted strategy for identifying men who may develop PCa is advised, generally commencing at 50 yr of age and based on individualised life expectancy. The use of multiparametric magnetic resonance imaging in order to avoid unnecessary biopsies is recommended. When a biopsy is considered, a combination of targeted and regional biopsies should be performed. Prostate-specific membrane antigen positron emission tomography imaging is the most sensitive technique for identifying metastatic spread. Active surveillance is the appropriate management for men with low-risk PCa, as well as for selected favourable intermediate-risk patients with International Society of Urological Pathology grade group 2 lesions. Local therapies are addressed, as well as the management of persistent prostate-specific antigen after surgery. A recommendation to consider hypofractionation in intermediate-risk patients is provided. Patients with cN1 PCa should be offered a local treatment combined with long-term intensified hormonal treatment.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The evidence in the field of diagnosis, staging, and treatment of localised PCa is evolving rapidly. These PCa guidelines reflect the multidisciplinary nature of PCa management.

PATIENT SUMMARY

This article is the summary of the guidelines for "curable" prostate cancer. Prostate cancer is "found" through a multistep risk-based screening process. The objective is to find as many men as possible with a curable cancer. Prostate cancer is curable if it resides in the prostate; it is then classified into low-, intermediary-, and high-risk localised and locally advanced prostate cancer. These risk classes are the basis of the treatments. Low-risk prostate cancer is treated with "active surveillance", a treatment with excellent prognosis. For low-intermediary-risk active surveillance should also be discussed as an option. In other cases, active treatments, surgery, or radiation treatment should be discussed along with the potential side effects to allow shared decision-making.

Moderate hypofractionated radiotherapy for prostate cancer: 3-year toxicity results of a multicentre randomized phase 3, non-inferiority trial

BACKGROUND AND PURPOSE

Moderate hypofractionated radiotherapy (HFRT) is a standard treatment for prostate cancer patients. We compared 2 moderate HFRT regimens, with a biologically equivalent dose of 80 Gy in 2 Gy fractions, with a modest simultaneous integrated boost to the dominant intraprostatic lesion.

MATERIAL AND METHODS

This is a multicenter, non-inferiority, randomized phase 3 trial with acute toxicity as the primary endpoint, comparing: 56 Gy in 4 weeks (16x3.5 Gy, 4 days/week, Arm A) with 67 Gy in 5 weeks (25x2.68 Gy, 5 days/week, Arm B). The H0 hypothesis is that both regimens are equivalent in terms of acute grade ≥ 2 gastro-intestinal toxicity, defined as a difference in acute grade ≥ 2 gastro-intestinal toxicity of ≤ 10 %. Here we report on acute and late toxicity.

RESULTS

We included 170 patients in Arm A and 172 patients in Arm B. The median follow-up time for all patients was 42 months. Acute grade ≥ 2 gastrointestinal toxicity was reported by 24 % of patients in both groups. Acute grade 2 and 3 urinary toxicity was observed in 52 % and 9 % of patients in Arm A and 53 % and 7 % in Arm B. Late grade 2 and grade ≥ 3 gastrointestinal toxicity occurred in 19 % and 4 % of patients in Arm A compared with 15 % and 4 % in Arm B. Late grade 2 and grade ≥ 3 urinary toxicity was observed in 37 % and 10 % of patients in Arm A and 36 % and 6 % in Arm B.

CONCLUSION

This analysis confirms that both HFRT regimens are safe and equivalent in terms of acute grade ≥ 2 gastrointestinal toxicity.

Evaluation of the trend of set-up errors during the treatment period using set-up margin in prostate radiotherapy

Accurate information on set-up error during radiotherapy is essential for determining the optimal number of treatments in hypofractionated radiotherapy for prostate cancer. This necessitates careful control by the radiotherapy staff to assess the patient's condition. This study aimed to develop an evaluation method of the temporal trends in a patient's specific prostate movement during treatment using image matching and margin values. This study included 65 patients who underwent prostate volumetric modulated arc therapy (mean treatment time, 87.2 s). Set-up errors were assessed using bone, inter-, and intra-fraction marker matching across 39 fractions. The set-up margin was determined by dividing the four periods into 39 fractions using Stroom's formula and correlation coefficient. The intra-fraction set-up error was biased in the anterior-superior (AS) direction during treatment. The temporal trend of set-up errors during radiotherapy slightly increased based on bone matching and inter-fraction marker matching, with a 1.6-mm difference in the set-up margin fractions 11 to 20. The correlation coefficient of the mean prostate movement during treatment significantly decreased in the superior-inferior direction, while remaining high in the left-right and anterior-posterior directions. Image matching contributed significantly to the improvement of set-up errors; however, careful attention is needed for prostate movement in the AS direction, particularly during short treatment times. Understanding the trend of set-up errors during the treatment period is essential in numerical information sharing on patient condition and evaluating the margins for tailored hypo-fractionated radiotherapy, considering the facility's image-guided radiation therapy technology.

Risk-Tailoring Radiotherapy for Endometrial Cancer: A Narrative Review

Endometrial cancer is the most common gynecologic cancer in the United States and it contributes to the second most gynecologic cancer-related deaths. With upfront surgery, the specific characteristics of both the patient and tumor allow for risk-tailored treatment algorithms including adjuvant radiotherapy and systemic therapy. In this narrative review, we discuss the current radiation treatment paradigm for endometrial cancer with an emphasis on various radiotherapy modalities, techniques, and dosing regimens. We then elaborate on how to tailor radiotherapy treatment courses in combination with other cancer-directed treatments, including chemotherapy and immunotherapy. In conclusion, this review summarizes ongoing research that aims to further individualize radiotherapy regimens for individuals in an attempt to improve patient outcomes.

Simultaneous Focal Boost With Stereotactic Radiation Therapy for Localized Intermediate- to High-Risk Prostate Cancer: Primary Outcomes of the SPARC Phase 2 Trial

PURPOSE

Dose-escalated radiation therapy is associated with better biochemical control at the expense of toxicity. Stereotactic body radiation therapy (SBRT) with dose escalation to the dominant intraprostatic lesion (DIL) provides a logical approach to improve outcomes in high-risk disease while limiting toxicity. This study evaluated the toxicity and quality of life (QoL) with CyberKnife-based SBRT and simultaneous integrated boost in localized prostate cancer.

METHODS AND MATERIALS

Eligible participants included newly diagnosed, biopsy-proven unfavorable intermediate- to high-risk localized prostate cancer (at least 1 of the following: Gleason ≥4+3, magnetic resonance imaging(MRI)-defined T3a N0, prostate-specific antigen ≥20) with up to 2 MRI-identified DILs. Participants received 36.25 Gy in 5 fractions on alternative days with a simultaneous boost to DIL up to 47.5 Gy as allowed by organ-at-risk constraints delivered by CyberKnife. All participants received androgen deprivation therapy. The primary outcome measure was acute grade 2+ genitourinary toxicity. Acute and late genitourinary and gastrointestinal toxicity using Radiation Therapy Oncology Group scoring, biochemical parameters, International Prostate Symptom Score, International Index of Erectile Function 5, and EQ-5D QoL outcomes were assessed.

RESULTS

Between 2013 and 2023, 20 participants were enrolled with a median follow-up of 30 months. The median D95 dose to DIL was 47.43 Gy. Cumulative acute grade 2+ genitourinary and gastrointestinal toxicity were 25% and 30%, respectively. One patient developed acute grade 3 genitourinary toxicity (5%). There is no late grade 3 genitourinary or gastrointestinal toxicity to date. International Prostate Symptom Score and urinary QoL scores recovered to baseline by 6 months. Patient-reported outcomes showed no significant change in EQ-5D QoL scores at 12 weeks and 1 year. There are no cases of biochemical relapse reported to date.

CONCLUSIONS

CyberKnife SBRT-delivered dose of 36.25 Gy to the prostate with a simultaneous integrated boost up to 47.5 Gy is well tolerated. Acute and late genitourinary and gastrointestinal toxicity rates are comparable to other contemporary SBRT trials and series with focal boost.

Extreme-hypofractionated RT with concomitant boost to the DIL in PCa: a 5-year update on oncological and patient-reported outcomes for the phase II trial "GIVE ME FIVE"

AIM

The present work reports updated oncological results and patients-reported outcomes at 5 years of phase II trial "Short-term high precision RT for early prostate cancer with SIB to the dominant intraprostatic lesion (DIL) for patients with early-stage PCa".

METHODS

Data from patients enrolled within AIRC IG-13218 (NCT01913717) trial were analyzed. Clinical and GU/GI toxicity assessment and PSA measurements were performed every 3 months for at least 2 years after RT end. QoL of enrolled patients was assessed by IPSS, EORTC QLQ-C30, EORTC QLQ-PR25, and IIEF-5. Patients' score changes were calculated at the end of RT and at 1, 12, and 60 months after RT.

RESULTS

A total of 65 patients were included. At a median follow-up of 5 years, OS resulted 86%. Biochemical and clinical progression-free survival at 5 years were 95%. The median PSA at baseline was 6.07 ng/ml, while at last follow-up resulted 0.25 ng/ml. IPSS showed a statistically significant variation in urinary function from baseline (p = 0.002), with the most relevant deterioration 1 month after RT, with a recovery toward baseline at 12 months (p ≤ 0.0001). A numerical improvement in QoL according to the EORTC QLQ-C30 has been reported although not statistically significant. No change in sexual activity was recorded after RT.

CONCLUSIONS

The study confirms that extreme hypofractionation with a DIL boost is safe and effective, with no severe effects on the QoL. The increasing dose to the DIL does not worsen the RT toxicity, thus opening the possibility of an even more escalated treatment.

Impact of Interfractional Bladder and Trigone Displacement and Deformation on Radiation Exposure and Subsequent Acute Genitourinary Toxicity: A Post Hoc Analysis of Patients Treated with Magnetic Resonance Imaging-Guided Prostate Stereotactic Body Radiation Therapy in a Phase 3 Randomized Trial

PURPOSE

Emerging data suggest that trigone dosimetry may be more associated with poststereotactic body radiation therapy (SBRT) urinary toxicity than whole bladder dosimetry. We quantify the dosimetric effect of interfractional displacement and deformation of the whole bladder and trigone during prostate SBRT using on-board, pretreatment 0.35T magnetic resonance images (MRI).

METHODS AND MATERIALS

Seventy-seven patients treated with MRI-guided prostate SBRT (40 Gy/5 fractions) on the MRI arm of a phase 3 single-center randomized trial were included. Bladder and trigone structures were contoured on images obtained from a 0.35T simulation MRI and 5 on-board pretreatment MRIs. Dice similarity coefficient (DSC) scores and changes in volume between simulation and daily treatments were calculated. Dosimetric parameters including Dmax, D0.03 cc, Dmean, V40 Gy, V39 Gy, V38 Gy, and V20 Gy for the bladder and trigone for the simulation and daily treatments were collected. Both physician-scored (Common Terminology Criteria for Adverse Events, version 4.03 scale) as well as patient-reported (International Prostate Symptom Scores and the Expanded Prostate Cancer Index Composite-26 scores) acute genitourinary (GU) toxicity outcomes were collected and analyzed.

RESULTS

The average treatment bladder volume was about 30% smaller than the simulation bladder volume; however, the trigone volume remained fairly consistent despite being positively correlated with total bladder volume. Overall, the trigone accounted for <2% of the bladder volume. Median DSC for the bladder was 0.79, whereas the median DSC of the trigone was only 0.33. No statistically significant associations between our selected bladder and trigonal dosimetric parameters and grade ≥2 GU toxicity were identified, although numerically, patients with GU toxicity (grade ≥2) had higher intermediate doses to the bladder (V20 Gy and Dmean) and larger volumes exposed to higher doses in the trigone (V40 Gy, V39 Gy, and V38 Gy).

CONCLUSIONS

The trigone exhibits little volume change, but considerable interfractional displacement/deformation. As a result, the relative volume of the trigone receiving high doses during prostate SBRT varies substantially between fractions, which could influence GU toxicity and may not be predicted by radiation planning dosimetry.

Long term update on toxicity and survival of a phase II trial of linac-based stereotactic body radiation therapy for low-intermediate risk prostate cancer

BACKGROUND

In 2016 we published a phase II study exploring safety and efficacy of Stereotactic Body Radiation Therapy (SBRT) delivered with Volumetric Modulated Arc Therapy (VMAT) and Flattening Filter Free (FFF) beams techniques in prostate cancer (PC) patients. We present herein the updated results on late toxicity and long-term survival.

METHODS

Patients enrolled in the study had a biopsy-confirmed localized PC and the features of a low- or intermediate-risk disease (National Comprehensive Network Criteria). The radiotherapy (RT) schedule consisted of 35 Gy delivered in five fractions every other day. Toxicities were registered according to the common toxicity adverse events v4.0. Biochemical recurrence was defined as an increase of prostate specific antigen after nadir, confirmed at least once. Local recurrence (LR) and distant metastases were detected either with Choline- or PSMA-PET/CT scans. Kaplan-Meier curves for Biochemical Recurrence-Free Survival (BFS), Local Control (LC), Distant Metastasis Free Survival (DMFS) and Cancer Specific Survival, were calculated by using MedCalc.

RESULTS

Ninety patients were submitted to SBRT between February 2012 and March 2015. Fifty-eight patients (64.5%) had a Gleason Score of 6, while 32 (35.5%) had a Gleason Score of 7. A late grade 1 Genito-Urinary toxicity was observed in 54.5% of patients while a grade 2 in 3.3%. A late Gastro-intestinal grade 1 toxicity was reported in 18.9% of patients, while a grade 2 in 2.2%. Erectile dysfunction was reported by 13% of patients No heavier toxicities were observed. At a median follow-up of 102 months, 5- and 8-year BFS were 93.0% and 84.4% respectively, 5- and 8-year LC were 95.2% and 87.0% respectively, 5- and 8-year DMFS were 95.3% and 88.4%, respectively.

CONCLUSIONS

This long-term update confirms that SBRT is a valid therapeutic strategy for low-intermediate risk PC. RT with VMAT and FFF warrants optimal results in terms of toxicity and disease control.

The Status and Challenges for Prostate Stereotactic Body Radiation Therapy Treatments in United States Proton Therapy Centers: An NRG Oncology Practice Survey

Purpose

To report the current practice pattern of the proton stereotactic body radiation therapy (SBRT) for prostate treatments.

Materials and Methods

A survey was designed to inquire about the practice of proton SBRT treatment for prostate cancer. The survey was distributed to all 30 proton therapy centers in the United States that participate in the National Clinical Trial Network in February, 2023. The survey focused on usage, patient selection criteria, prescriptions, target contours, dose constraints, treatment plan optimization and evaluation methods, patient-specific QA, and image-guided radiation therapy (IGRT) methods.

Results

We received responses from 25 centers (83% participation). Only 8 respondent proton centers (32%) reported performing SBRT of the prostate. The remaining 17 centers cited 3 primary reasons for not offering this treatment: no clinical need, lack of volumetric imaging, and/or lack of clinical evidence. Only 1 center cited the reduction in overall reimbursement as a concern for not offering prostate SBRT. Several common practices among the 8 centers offering SBRT for the prostate were noted, such as using Hydrogel spacers, fiducial markers, and magnetic resonance imaging (MRI) for target delineation. Most proton centers (87.5%) utilized pencil beam scanning (PBS) delivery and completed Imaging and Radiation Oncology Core (IROC) phantom credentialing. Treatment planning typically used parallel opposed lateral beams, and consistent parameters for setup and range uncertainties were used for plan optimization and robustness evaluation. Measurements-based patient-specific QA, beam delivery every other day, fiducial contours for IGRT, and total doses of 35 to 40 GyRBE were consistent across all centers. However, there was no consensus on the risk levels for patient selection.

Conclusion

Prostate SBRT is used in about 1/3 of proton centers in the US. There was a significant consistency in practices among proton centers treating with proton SBRT. It is possible that the adoption of proton SBRT may become more common if proton SBRT is more commonly offered in clinical trials.

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.

Enhancing Androgen Deprivation Therapy (ADT) integration in prostate cancer: Insights for Stereotactic Body Radiotherapy (SBRT) and brachytherapy modalities

The utilization of Androgen Deprivation Therapy (ADT) in conjunction with Stereotactic Body Radiotherapy (SBRT) and Brachytherapy (BT) boost in prostate cancer treatment is a subject of ongoing debate and evolving clinical practice. While contemporary trends lean towards underutilizing ADT with these modalities, existing evidence suggests that its omission may lead to potentially inferior oncologic outcomes. Recommendations for ADT use should be patient-centric, considering individual risk profiles and comorbidities, with a focus on achieving optimal oncologic outcomes while minimizing potential side effects. Ongoing clinical trials, such as PACE-C, SPA, SHIP 0804, and SHIP 36B, are anticipated to provide valuable insights into the optimal use and duration of ADT in both SBRT and BT settings. Until new evidence emerges, it is recommended to initiate ADT for unfavorable intermediate-risk and high-risk prostate cancer patients undergoing radiotherapy, with a minimum duration of 6 months for unfavorable intermediate-risk patients and at least 12 months for those with high-risk characteristics. The decision to incorporate ADT into these radiation therapy modalities should be individualized, acknowledging the unique needs of each patient and emphasizing a tailored approach to achieve the best possible oncologic outcomes.

Stereotactic body radiotherapy (SIB-VMAT technique) to dominant intraprostatic lesion (DIL) for localized prostate cancer: a dose-escalation trial (DESTROY-4)

PURPOSE

DESTROY-4 (DOSE-ESCALATION STUDY OF STEREOTACTIC BODY RADIATION THERAPY) was a Phase I trial aimed to evaluate the safety and the feasibility of escalating doses of stereotactic body radiation therapy (SBRT) on MRI-defined Dominant Intraprostatic Lesion (DIL) in low- and intermediate-risk pCa patients using a simultaneous integrated boost-volumetric arc therapy (SIB-VMAT) technique.

METHODS

Eligible patients included those with low- and intermediate-risk prostate carcinoma (NCCN risk classes) and an International Prostatic Symptoms Score (IPSS) ≤ 15. No restriction about DIL and prostate volumes was set. Pretreatment preparation required an enema and the placement of intraprostatic gold fiducials. SBRT was delivered in five consecutive daily fractions. For the first three patients, the DIL radiation dose was set at 8 Gy per fraction up to a total dose of 40 Gy (PTV1) and was gradually increased in succeeding cohorts to total doses of 42.5 Gy, 45.0 Gy, 47.5 Gy, and finally, 50.0 Gy, while keeping the prescription of 35 Gy/7 Gy per fraction for the entire prostate gland. Dose-limiting toxicity (DLT) was defined as grade 3 or worse gastrointestinal (GI) or genitourinary (GU) toxicity occurring within 90 days of follow-up (Common Terminology Criteria of Adverse Events scale 4.0). Patients completed quality-of-life questionnaires at defined intervals.

RESULTS

Twenty-four patients with a median age of 75 (range, 58-89) years were enrolled. The median follow-up was 26.3 months (8.9-84 months). 66.7% of patients were classified as intermediate-risk groups, while the others were low-risk groups, according to the NCCN guidelines. Enrolled patients were treated as follows: 8 patients (40 Gy), 5 patients (42.5 Gy), 4 patients (45 Gy), 4 patients (47.5 Gy), and 3 patients (50 Gy). No severe acute toxicities were observed. G1 and G2 acute GU toxicities occurred in 4 (16%) and 3 patients (12.5%), respectively. Two patients (8.3%) and 3 patients (12.5%) experienced G1 and G2 GI toxicities, respectively. Since no DLTs were observed, 50 Gy in five fractions was considered the MTD. The median nadir PSA was 0.20 ng/mL. A slight improvement in QoL values was registered after the treatment.

CONCLUSION

This trial confirms the feasibility and safety of a total SIB-VMAT dose of 35 Gy on the whole gland and 50 Gy on DIL in 5 fractions daily administered in a well-selected low- and intermediate-risk prostate carcinoma population. A phase II study is ongoing to confirm the tolerability of the schedule and assess the efficacy.

Stereotactic Body Radiation Therapy: A Radiosurgery Society Guide to the Treatment of Localized Prostate Cancer Illustrated by Challenging Cases

Traditionally, external beam radiotherapy (EBRT) for localized prostate cancer (PCa) involved lengthy courses with low daily doses. However, advancements in radiation delivery and a better understanding of prostate radiobiology have enabled the development of shorter courses of EBRT. Ultrahypofractionated radiotherapy, administering doses greater than 5 Gy per fraction, is now considered a standard of care regimen for localized PCa, particularly for intermediate-risk disease. Stereotactic body radiotherapy (SBRT), a specific type of ultrahypofractionated radiotherapy employing advanced planning, imaging, and treatment technology to deliver in five or fewer fractions, is gaining prominence as a cost-effective, convenient, and safe alternative to longer radiotherapy courses. It is crucial to address practical considerations related to patient selection, fractionation scheme, target delineation, and planning objectives. This is especially important in challenging clinical situations where clear evidence for guidance may be lacking. The Radiosurgery Society endorses this case-based guide with the aim of providing a practical framework for delivering SBRT to the intact prostate, exemplified by two case studies. The article will explore common SBRT dose/fractionation schemes and dose constraints for organs-at-risk. Additionally, it will review existing evidence and expert opinions on topics such as SBRT dose escalation, the use of rectal spacers, the role of androgen deprivation therapy in the context of SBRT, SBRT in special patient populations (e.g., high-risk disease, large prostate, high baseline urinary symptom burdens, and inflammatory bowel disease), as well as new imaging-guidance techniques like Magnetic Resonance Imaging for SBRT delivery.

Interim Toxicity Analysis From the Randomized HERMES Trial of 2- and 5-Fraction Magnetic Resonance Imaging-Guided Adaptive Prostate Radiation Therapy

PURPOSE

Ultrahypofractionated radiation therapy (UHRT) is an effective treatment for localized prostate cancer with an acceptable toxicity profile; boosting the visible intraprostatic tumor has been shown to improve biochemical disease-free survival with no significant effect on genitourinary (GU) and gastrointestinal (GI) toxicity.

METHODS AND MATERIALS

HERMES is a single-center noncomparative randomized phase 2 trial in men with intermediate or lower high risk prostate cancer. Patients were allocated (1:1) to 36.25 Gy in 5 fractions over 2 weeks or 24 Gy in 2 fractions over 8 days with an integrated boost to the magnetic resonance imaging (MRI) visible tumor of 27 Gy in 2 fractions. A minimization algorithm with a random element with risk group as a balancing factor was used for participant randomization. Treatment was delivered on the Unity MR-Linac (Elekta AB) with daily online adaption. The primary endpoint was acute GU Common Terminology Criteria for Adverse Events version 5.0 toxicity with the aim of excluding a doubling of the rate of acute grade 2+ GU toxicity seen in PACE. Analysis was by treatment received and included all participants who received at least 1 fraction of study treatment. This interim analysis was prespecified (stage 1 of a 2-stage Simon design) for when 10 participants in each treatment group had completed the acute toxicity monitoring period (12 weeks after radiation therapy).

RESULTS

Acute grade 2 GU toxicity was reported in 1 (10%) patient in the 5-fraction group and 2 (20%) patients in the 2-fraction group. No grade 3+ GU toxicities were reported.

CONCLUSIONS

At this interim analysis, the rate of GU toxicity in the 2-fraction and 5-fraction treatment groups was found to be below the prespecified threshold (5/10 grade 2+) and continuation of the study to complete recruitment of 23 participants per group was recommended.

The impact of transportation mode, socioeconomic deprivation and rurality on travel times to radiotherapy and surgical services for patients with prostate cancer: A national population-based evaluation

BACKGROUND

The distances that patients have to travel can influence their access to cancer treatment. We investigated the determinants of travel time, separately for journeys by car and public transport, to centres providing radical surgery or radiotherapy for prostate cancer.

METHODS

Using national cancer registry records linked to administrative hospital data, we identified patients who had radical surgery or radiotherapy for prostate cancer between January 2017 and December 2018 in the English National Health Service. Estimated travel times from the patients' residential area to the nearest specialist surgical or radiotherapy centre were estimated for journeys by car and by public transport.

RESULTS

We included 13,186 men who had surgery and 26,581 who had radiotherapy. Estimated travel times by public transport (74.4 mins for surgery and 69.4 mins for radiotherapy) were more than twice as long as by car (33.4 mins and 29.1mins, respectively). Patients living in more socially deprived neighbourhoods in rural areas had the longest travel times to the nearest cancer treatment centres by car (62.0 mins for surgery and 52.1 mins for radiotherapy). Conversely patients living in more affluent neighbourhoods in urban conurbations had the shortest (18.7 mins for surgery and 17.9 mins for radiotherapy).

CONCLUSION

Travel times to cancer centres vary widely according to mode of transport, socioeconomic deprivation, and rurality. Policies changing the geographical configuration of cancer services should consider the impact on the expected travel times both by car and by public transport to avoid enhancing existing inequalities in access to treatment and patient outcomes.

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.

Dosimetric benefit of online treatment plan adaptation in stereotactic ultrahypofractionated MR-guided radiotherapy for localized prostate cancer

Background

Apart from superior soft tissue contrast, MR-guided stereotactic body radiation therapy (SBRT) offers the chance for daily online plan adaptation. This study reports on the comparison of dose parameters before and after online plan adaptation in MR-guided SBRT of localized prostate cancer.

Materials and methods

32 consecutive patients treated with ultrahypofractionated SBRT for localized prostate cancer within the prospective SMILE trial underwent a planning process for MR-guided radiotherapy with 37.5 Gy applied in 5 fractions. A base plan, derived from MRI simulation at an MRIdian Linac, was registered to daily MRI scans (predicted plan). Following target and OAR recontouring, the plan was reoptimized based on the daily anatomy (adapted plan). CTV and PTV coverage and doses at OAR were compared between predicted and adapted plans using linear mixed regression models.

Results

In 152 out of 160 fractions (95%), an adapted radiation plan was delivered. Mean CTV and PTV coverage increased by 1.4% and 4.5% after adaptation. 18% vs. 95% of the plans had a PTV coverage ≥95% before and after online adaptation, respectively. 78% vs. 100% of the plans had a CTV coverage ≥98% before and after online adaptation, respectively. The D0.2cc for both bladder and rectum were <38.5 Gy in 93% vs. 100% before and after online adaptation. The constraint at the urethra with a dose of <37.5 Gy was achieved in 59% vs. 93% before and after online adaptation.

Conclusion

Online adaptive plan adaptation improves target volume coverage and reduces doses to OAR in MR-guided SBRT of localized prostate cancer. Online plan adaptation could potentially further reduce acute and long-term side effects and improve local failure rates in MR-guided SBRT of localized prostate cancer.

Electromagnetic Transmitter-Based Prostate Gating for Dose-Escalated Linac-Based Stereotactic Body Radiation Therapy: An Evaluation of Intrafraction Motion

BACKGROUND

Stereotactic Body Radiotherapy (SBRT) is as a standard treatment for prostate cancer (PCa). Tight margins and high dose gradients are needed, and the precise localization of the target is mandatory. Our retrospective study reports our experience regarding the evaluation of intrafraction prostate motion during LINAC-based SBRT evaluated with a novel electromagnetic (EM) tracking device. This device consists of an integrated Foley catheter with a transmitter connected to a receiver placed on the treatment table.

METHODS

We analyzed 31 patients who received LINAC-based SBRT using flattening filter-free (FFF) volumetric modulated arc therapy (VMAT). The patients were scheduled to be treated for primary (n = 27) or an intraprostatic recurrent PCa (n = 4). A simulation CT scan was conducted while the patients had a filled bladder (100-150 cc) and an empty rectum, and an EM tracking device was used. The same rectal and bladder conditions were employed during the treatment. The patients received 36.25 Gy delivered over five consecutive fractions on the whole prostate and 40 Gy on the nodule(s) visible via MRI, both delivered with a Simultaneous Integrated Boost approach. The CTV-to-PTV margin was 2 mm for both the identified treatment volumes. Patient positioning was verified with XVI ConeBeam-CT (CBCT) matching before each fraction. When the signals exceeded a 2 mm threshold in any of the three spatial directions, the treatment was manually interrupted. A new XVI CBCT was performed if this offset lasted >20 s.

RESULTS

We analyzed data about 155 fractions. The median and mean treatment times, calculated per fraction, were 10 m31 s and 12 m44 s (range: 6 m36 s-65 m28 s), and 95% of the fractions were delivered with a maximum time of 27 m48 s. During treatment delivery, the mean and median number of XVI CBCT operations realized during the treatment were 2 and 1 (range: 0-11). During the treatment, the prostate was outside the CTV-to-PTV margin (2 mm), thus necessitating the stoppage of the delivery +/- a reacquisition of the XVI CBCT for 11.2%, 8.9%, and 3.9% of the delivery time in the vertical, longitudinal, and lateral direction, respectively.

CONCLUSIONS

We easily integrated an EM-transmitter-based gating for prostate LINAC-based SBRT into our normal daily workflow. Using this system, a 2 mm CTV-to-PTV margin could be safely applied. A small number of fractions showed a motion exceeding the predefined 2 mm threshold, which would have otherwise gone undetected without intrafraction motion management.

Quality of Decision Making in Radiation Oncology

High-quality decision making in radiation oncology requires the careful consideration of multiple factors. In addition to the evidence-based indications for curative or palliative radiotherapy, this article explores how, in routine clinical practice, we also need to account for many other factors when making high-quality decisions. Foremost are patient-related factors, including preference, and the complex interplay between age, frailty and comorbidities, especially with an ageing cancer population. Whilst clinical practice guidelines inform our decisions, we need to account for their applicability in different patient groups and different resource settings. With particular reference to curative-intent radiotherapy, we explore decisions regarding dose fractionation schedules, use of newer radiotherapy technologies and multimodality treatment considerations that contribute to personalised patient-centred care.

Converting between the International Prostate Symptom Score (IPSS) and the Expanded Prostate Cancer Index Composite (EPIC) urinary subscales: modeling and external validation

BACKGROUND

Prostate-related quality of life can be assessed with a variety of different questionnaires. The 50-item Expanded Prostate Cancer Index Composite (EPIC) and the International Prostate Symptom Score (IPSS) are two widely used options. The goal of this study was, therefore, to develop and validate a model that is able to convert between the EPIC and the IPSS to enable comparisons across different studies.

METHODS

Three hundred forty-seven consecutive patients who had previously received radiotherapy and surgery for prostate cancer at two institutions in Switzerland and Germany were contacted via mail and instructed to complete both questionnaires. The Swiss cohort was used to train and internally validate different machine learning models using fourfold cross-validation. The German cohort was used for external validation.

RESULTS

Converting between the EPIC Urinary Irritative/Obstructive subscale and the IPSS using linear regressions resulted in mean absolute errors (MAEs) of 3.88 and 6.12, which is below the respective previously published minimal important differences (MIDs) of 5.2 and 10 points. Converting between the EPIC Urinary Summary and the IPSS was less accurate with MAEs of 5.13 and 10.45, similar to the MIDs. More complex model architectures did not result in improved performance in this study. The study was limited to the German versions of the respective questionnaires.

CONCLUSIONS

Linear regressions can be used to convert between the IPSS and the EPIC Urinary subscales. While the equations obtained in this study can be used to compare results across clinical trials, they should not be used to inform clinical decision-making in individual patients.

TRIAL REGISTRATION

This study was retrospectively registered on clinicaltrials.gov on January 14th, 2022, under the registration number NCT05192876.

Disease control outcomes of stereotactic body radiation therapy or moderate hypo-fractionation for prostate cancer: Real-world experience at two Canadian centers

BACKGROUND

Advantages of using stereotactic body radiation therapy to treat prostate cancer include short treatment times, decreased costs, and limited toxicity. Randomized trial outcomes comparing 5-fraction stereotactic body radiation therapy to conventionally fractionated radiotherapy or hypo-fractionated radiation therapy are pending.

OBJECTIVE

We report the 10-year experience with 5-fraction stereotactic body radiation therapy and hypo-fractionated radiation therapy at two Canadian centers.

MATERIAL AND METHODS

Patients with low- or intermediate-risk prostate cancer treated with stereotactic body radiation therapy alone (35-40 Gy in 5 fractions) or hypo-fractionated radiation therapy alone (60-62 Gy in 20 fractions) in the period of July 2010 and June 2020. The biochemical relapse-free survival, PSA nadir, interval time to PSA nadir, time to biochemical recurrence (2 ng/ml above PSA nadir) and overall survival were reviewed. Outcomes between treatment groups were compared after propensity-matching by patient baseline characteristics. Kaplan-Meier curves were used to assess biochemical relapse-free survival and overall survival.

RESULTS

We identified 205 and 513 patients with low or intermediate-risk prostate cancer who were treated with stereotactic body radiation therapy or hypo-fractionation, respectively. Intermediate-risk category composed 81% and 95% of the stereotactic body radiation therapy and hypo-fractionated radiation therapy cohorts, respectively. After a median follow up of 58.6 months for the stereotactic body radiation therapy cohort and 45.0 months for the hypo-fractionated cohort, biochemical relapse-free survival and overall survival were not significantly different between treatment groups. The 5-year biochemical relapse-free survival rates were 92.1% and 93.6% and overall survival rates were 96.4% and 95.0% for the stereotactic body radiation therapy and hypo-fractionated cohorts, respectively, after propensity-matching. Stereotactic body radiation therapy resulted in a significantly lower PSA nadir (0.18 ng/ml) compared to hypo-fractionated radiation therapy (0.48 ng/ml) in patients with low-risk prostate cancer. Mean time to biochemical recurrence was not different between treatment groups.

CONCLUSIONS

Stereotactic body radiation therapy is an effective treatment option for low and intermediate-risk prostate cancer with encouraging biochemical relapse-free survival and overall survival rates comparable with hypo-fractionated radiation therapy.

Ultra-hypofractionated prostate cancer radiotherapy: Dosimetric impact of real-time intrafraction prostate motion and daily anatomical changes

PURPOSE

To retrospectively assess the differences between planned and delivered dose during ultra-hypofractionated (UHF) prostate cancer treatments, by evaluating the dosimetric impact of daily anatomical variations alone, and in combination with prostate intrafraction motion.

METHODS

Prostate intrafraction motion was recorded with a transperineal ultrasound probe in 15 patients treated by UHF radiotherapy (36.25 Gy/5 fractions). The dosimetric objective was to cover 99 % of the clinical target volume with the 100 % prescription isodose line. After treatment, planning CT (pCT) images were deformably registered onto daily Cone Beam CT to generate pseudo-CT for dose accumulation (accumulated CT, aCT). The interplay effect was accounted by synchronizing prostatic shifts and beam geometry. Finally, the shifted dose maps were accumulated (moved-accumulated CT, maCT).

RESULTS

No significant change in daily CTV volumes was observed. Conversely, CTV V100% was 98.2 ± 0.8 % and 94.7 ± 2.6 % on aCT and maCT, respectively, compared with 99.5 ± 0.2 % on pCT (p < 0.0001). Bladder volume was smaller than planned in 76 % of fractions and D5cc was 33.8 ± 3.2 Gy and 34.4 ± 3.4 Gy on aCT (p = 0.02) and maCT (p = 0.01) compared with the pCT (36.0 ± 1.1 Gy). The rectum was smaller than planned in 50.3 % of fractions, but the dosimetric differences were not statistically significant, except for D1cc, found smaller on the maCT (33.2 ± 3.2 Gy, p = 0.02) compared with the pCT (35.3 ± 0.7 Gy).

CONCLUSIONS

Anatomical variations and prostate movements had more important dosimetric impact than anatomical variations alone, although, in some cases, the two phenomena compensated. Therefore, an efficient IGRT protocol is required for treatment implementation to reduce setup errors and control intrafraction motion.

Retrospective study on the toxicity induced by stereotactic body radiotherapy: overview of the reunion experience on prostate cancer in elderly patients

Introduction

Prostate cancer is the fourth most commonly diagnosed cancer among men worldwide. Various tools are used to manage disease such as conventional radiotherapy. However, it has been demonstrated that large prostate volumes were often associated with higher rates of genitourinary and gastrointestinal toxicities. Currently, the improvements in radiotherapy technology have led to the development of stereotactic body radiotherapy, which delivers higher and much more accurate radiation doses. In order to complete literature data about short-term outcome and short-term toxic effects of stereotactic body radiotherapy, we aimed to share our experience about gastrointestinal and genitourinary toxicities associated with stereotactic body radiotherapy in prostate cancer in patients over 70 years old.

Methods

We retrospectively reviewed the medical records of elderly patients with prostate cancer treated between 2021 and 2022. The elderly patients were treated with a non-coplanar robotic stereotactic body radiotherapy platform using real-time tracking of implanted fiducials. The prostate, with or without part of the seminal vesicles, was treated with a total dose of 36.25 Gy delivered in five fractions, each fraction being administered every other day.

Results

We analyzed a total of 80 elderly patients, comprising 38 low-, 37 intermediate- and 5 high-risk patients. The median follow-up duration was 12 months. We did not observe biochemical/clinical recurrence, distant metastasis, or death. Grade 2 acute genitourinary toxicity was observed in 9 patients (11.25%) and Grade 2 acute gastrointestinal toxicity in 4 patients (5.0%). We did not observe any grade 3 or more acute or late toxicities.

Conclusion

Over the follow-up period, we noted a low frequency of gastrointestinal and genitourinary toxicities induced by stereotactic body radiotherapy in the context of prostate cancer in elderly patients. Therefore, stereotactic body radiotherapy seems to represent a promising treatment option for elderly patients, with acceptable acute toxicity.

Prostate Virtual High-dose-rate Brachytherapy Boost: 5-Year Results from the PROMETHEUS Prospective Multicentre Trial

BACKGROUND AND OBJECTIVE

Despite the high efficacy of high-dose-rate brachytherapy boost (HDRB) in the management of prostate cancer (PC), use of this approach is declining. Similar dosimetry can be achieved using stereotactic body radiotherapy or "virtual HDRB" (vHDRB). The aim of the multicentre, single-arm, phase 2 PROMETHEUS trial (ACTRN12615000223538) was to evaluate the safety and efficacy of vHDRB in patients with PC.

METHODS

Patients with intermediate-risk PC or selected patients with high-risk PC were eligible for inclusion. vHDRB was given as 19-20 Gy in two fractions, delivered 1 wk apart, followed by conventionally fractionated external beam radiotherapy (EBRT) at 46 Gy in 23 fractions or 36 Gy in 12 fractions. The primary endpoint was the biochemical/clinical relapse-free rate (bcRFR). Toxicity was graded using Common Terminology Criteria for Adverse Events version 4 and quality of life (QoL) data were collected used the Expanded Prostate Cancer Index Composite-26 questionnaire.

KEY FINDINGS AND LIMITATIONS

From March 2014 to December 2018, 151 patients (74% intermediate risk, 26% high risk) with a median age of 69 yr were treated across five centres. Median follow-up was 60 mo. The 5-yr bcRFR was 94.1% (95% confidence interval [CI] 90-98%) and the local control rate was 98.7%. Acute grade 2 gastrointestinal (GI) and genitourinary (GU) toxicity occurred in 6.6% and 23.2% of patients, respectively, with no acute grade 3 toxicity. At 60 mo after treatment, the prevalence of late grade ≥2 GI toxicity was 1.7% (95% CI 0.3-6.5%) and the prevalence of late grade ≥2 GU toxicity was 3.3% (95% CI 1.1-8.8%). Between baseline and 60 mo, QoL improved for urinary obstructive and hormonal domains, was stable for the bowel domain, and deteriorated slightly for the sexual and urinary incontinence domains.

CONCLUSIONS

Delivery of gantry-based vHDRB followed by conventionally fractionated EBRT is feasible in a multicentre setting, with high 5-yr bcRFR and low toxicity. This approach is being compared with prostate ultrahypofractionated radiotherapy in the TROG 18.01 NINJA randomised trial (ACTRN12618001806257).

PATIENT SUMMARY

The PROMETHEUS trial investigated noninvasive high-dose precision radiotherapy combined with conventional radiotherapy in patients with prostate cancer. We found that this new technique was well tolerated and resulted in better cancer control outcomes than historically reported.

HypoFocal SRT Trial: Ultra-hypofractionated focal salvage radiotherapy for isolated prostate bed recurrence after radical prostatectomy; single-arm phase II study; clinical trial protocol

INTRODUCTION

Despite radical prostatectomy (RP) and radiotherapy (RT) being established treatments for localised prostate cancer, a significant number of patients experience recurrent disease. While conventionally fractionated RT is still being used as a standard treatment in the postoperative setting, ultra-hypofractionated RT has emerged as a viable option with encouraging results in patients with localised disease in the primary setting. In addition, recent technological advancements in RT delivery and precise definition of isolated macroscopic recurrence within the prostate bed using prostate-specific membrane antigen-positron emission tomography (PSMA-PET) and multiparametric MRI (mpMRI) allow the exploration of ultra-hypofractionated schedules in the salvage setting using five fractions.

METHODS AND ANALYSIS

In this single-arm prospective phase II multicentre trial, 36 patients with node-negative prostate adenocarcinoma treated with RP at least 6 months before trial registration, tumour stage pT2a-3b, R0-1, pN0 or cN0 according to the UICC TNM 2009 and evidence of measurable local recurrence within the prostate bed detected by PSMA PET/CT and mpMRI within the last 3 months, will be included. The patients will undergo focal ultra-hypofractionated salvage RT with 34 Gy in five fractions every other day to the site of local recurrence in combination with 6 months of androgen deprivation therapy. The primary outcome of this study is biochemical relapse-free survival at 2 years. Secondary outcomes include acute side effects (until 90 days after the end of RT) of grade 3 or higher based on Common Terminology Criteria for Adverse Events V.5, progression-free survival, metastasis-free survival, late side effects and the quality of life (based on European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-C30, QLQ-PR25).

ETHICS AND DISSEMINATION

The study has received ethical approval from the Ethics Commission of the Canton of Bern (KEK-BE 2022-01026). Academic dissemination will occur through publications and conference presentations.

TRIAL REGISTRATION NUMBER

NCT05746806.

Acute and long-term toxicity in primary hypofractionated external photon radiation therapy in patients with localized prostate cancer

BACKGROUND

Compelling evidence exists for the iso-effectiveness and safety of moderate hypofractionated radiotherapy (Hypo-RT) schedules [1, 2]. However, international guidelines are not congruent regarding recommendation of ultrahypofractionated radiotherapy (UHF-RT) to all risk groups.

METHODS

The current review gives an overview of clinically relevant toxicity extracted from major randomized controlled trials (RCT) trials comparing conventional to hypofractionated regimes in the primary setting of external photon radiation. Functional impairments are reported by using physician-rated and patient-reported scores using validated questionnaires.

RESULTS

The uncertain radiobiology of the urethra/bladder when applying extreme hypofractionation may have contributed to worse acute urinary toxicity score in the Scandinavian UHF-RT and worse subacute toxicity in PACE-B. The observed trend of increased acute GI toxicity in several moderate Hypo-RT trials and one UHF-RT trial, the Scandinavian Hypo-RT PC trial, could be associated to the different planning margins and radiation dose schedules.

CONCLUSION

Nevertheless, Hypo-RT has gained ground for patients with localized PCa and further improvements may be achieved by inclusion of genetically assessed radiation sensitivity. Several RCTs in Hypo-RT have shown non-inferior outcome and well-tolerated treatment toxicity by physician-rated scores. In the future, we suggest that toxicity should be measured by patient-reported outcome (PRO) using comparable questionnaires.