Long-term survival and toxicity in patients treated with high-dose intensity modulated radiation therapy for localized prostate cancer

Quantifying dose perturbations in high-risk prostate radiotherapy due to translational and rotational motion of prostate and pelvic lymph nodes

BACKGROUND

Radiotherapy of the prostate and the pelvic lymph nodes (LN) is a part of the standard of care treatment for high-risk prostate cancer. The independent translational and rotational (i.e., six-degrees-of-freedom, [6DoF]) motion of the prostate and LN target during and between fractions can perturb the dose distribution. However, no standard dose reconstruction method accounting for differential 6DoF target motion is available.

PURPOSE

We present a framework for monitoring motion-induced dose perturbations for two independently moving target volumes in 6DoF. The framework was used to determine the dose perturbation for the prostate and the LN target caused by differential 6DoF motion for a cohort of high-risk prostate cancer patients. As a potential first step toward real-time dose-guided high-risk prostate radiotherapy, we furthermore investigated if the dose reconstruction was fast enough for real-time application for both targets.

METHODS

Twenty high-risk prostate cancer patients were treated with 3-arc volumetric modulated arc therapy (VMAT). Kilovoltage intrafraction monitoring (KIM) with triggered kilovoltage (kV) images acquired every 3 throughout 7-10 fractions per patient was used for retrospective 6DoF intrafraction prostate motion estimation. The 6DoF interfraction LN motion was determined from a pelvic bone match between the planning CT and a post-treatment cone beam CT (CBCT). Using the retrospectively extracted motion, real-time 6DoF motion-including dose reconstruction was simulated using the in-house developed software DoseTracker. A data stream with the 6DoF target positions and linac parameters was broadcasted at a 3-Hz frequency to DoseTracker. In a continuous loop, DoseTracker calculated the target dose increments including the specified motion and, for comparison, without motion. The motion-induced change in D99.5% for the prostate CTV (ΔD99.5%) and in D98% for the LN CTV (ΔD98%) was calculated using the final cumulative dose of each fraction and averaged over all imaged fractions. The real-time reconstructed dose distribution of DoseTracker was benchmarked against a clinical treatment planning system (TPS) and it was investigated whether the calculation speed was fast enough to keep up with the incoming data stream.

RESULTS

Translational motion was largest in cranio-caudal (CC) direction (prostate: [-5.9, +8.4] mm; LN: [-9.9; +11.0] mm) and anterior-posterior (AP) direction (prostate:[-5.6; +6.9] mm; LN: [-9.6; +11.0] mm). The pitch was the largest rotation (prostate: [-22.5; +25.2] deg; LN: [-3.9; +5.5] deg). The prostate CTV ΔD99.5% was [-16.2; +2.5]% for single fractions and [-3.0; +1.7]% when averaged over all imaged fractions. The LN CTV ΔD98% was [-19.8; +1.2]% for single fractions and [-3.1; +0.9]% after averaging. Mean (Standard deviation) absolute dose errors in DoseTracker of 107.8% (Std: 1.9%) for the prostate and 105.5% (Std:1.4%) for the LN were corrected during dose reconstruction by automatically calculated normalization factors. It resulted in accurate calculation of the motion-induced dose errors with relative differences between DoseTracker and TPS dose calculations of -0.1% (Std: 0.5%) (prostate CTV ΔD99.5%) and -0.2% (Std: 0.5%) (LN CTV ΔD98%). The DoseTracker calculation was fast enough to keep up with the incoming inputs for all but two out of 107 184 dose calculations.

CONCLUSION

Using the developed framework for dose perturbation monitoring, we found that the differential 6DoF target motion caused substantial dose perturbation for individual fractions, which largely averaged out after several fractions. The framework was shown to provide reliable dose calculations and a sufficiently high-dose reconstruction speed to be applicable in real-time.

Proton therapy toxicity outcomes for localized prostate cancer: Long-term results at a comprehensive cancer center

Background

Proton therapy (PT) has unique biologic properties with excellent clinical outcomes for the management of localized prostate cancer. Here, we aim to characterize the toxicity of PT for patients with localized prostate cancer and propose mitigation strategies using a large institutional database.

Methods

We reviewed medical records of 2772 patients with localized prostate cancer treated with definitive PT between May 2006 through January 2020. Disease risk was stratified according to National Comprehensive Cancer Network guidelines as low [LR, n = 640]; favorable-intermediate [F-IR, n = 849]; unfavorable-intermediate [U-IR, n = 851]; high [HR, n = 315]; or very high [VHR, n = 117]. Descriptive statistics and Kaplan-Meier estimates assessed toxicity and freedom from biochemical relapse (FFBR).

Results

Median follow-up was 7.0 years. The median dose was 78 Gy(RBE)(range: 72-79.2 Gy) in 2.0 Gy(RBE) fractions; 63 % of patients received 78 Gy(RBE) in 39 fractions, and 29 % received 76 Gy(RBE) in 38 fractions. Overall rates of late grade ≥3 GU and GI toxicity were 0.87 % and 1.01 %, respectively. Two patients developed grade 4 late GU toxicity and seven patients with grade 4 late GI toxicity. All patients experiencing severe late grade 4 toxicities were treated to 78 Gy(RBE) in 39 fractions with 80 Gy(RBE) dose to the anterior rectal wall and/or bladder neck. The 10-year FFBR rates for patients with LR to U-IR disease were compared between those treated with 76 and 78 Gy(RBE); the rates were 94.5 % (95 % confidence interval [CI] 92.4-96.0 %) and 93.2 % (95 % CI 91.3-95.7 %), respectively (log-rank p = 0.22).

Conclusions

Proton therapy is associated with low rates of late grade ≥3 GU and GI toxicity. While rare, late grade 4 toxicities occurred in nine (0.3 %) patients. De-escalation to a total dose of 76 Gy(RBE) yields excellent clinical outcomes for patients with LR to U-IR disease with the potential for significant reductions in grade ≥3 late toxicity.

Exploring predictive molecules of acute adverse events in response to volumetric‑modulated arc therapy for prostate cancer using urinary metabolites

Volumetric-modulated arc therapy (VMAT) is a radiotherapy technique used to treat patients with localized prostate cancer, which is frequently associated with acute adverse events (AEs) that can affect subsequent treatment. Notably, the radiation dose of VMAT can be tailored to each patient. In the present study, a retrospective analysis was performed to predict acute AEs in response to a therapeutic high radiation dose rate based on urinary metabolomic molecules, which are easily collected as noninvasive biosamples. Urine samples from 11 patients with prostate cancer who were treated with VMAT (76 Gy/38 fractions) were collected. The study found that seven patients (~64%) exhibited genitourinary toxicity (Grade 1) and four patients had no AEs. A total of 630 urinary metabolites were then analyzed using a mass spectrometer (QTRAP6500+; AB SCIEX), and 234 relevant molecules for biological and clinical applications were extracted from the absolute quantified metabolite values using the MetaboINDICATOR tool. In the Grade 1 acute AE group, there was a significant negative correlation (rs=-0.297, P<0.05) between the number of VMAT fractions and total phospholipase A2 activity in the urine. Additionally, patients with Grade 1 AEs exhibited a decrease in PC aa C40:1, a phospholipid. These findings suggested that specific lipids found in urinary metabolites may serve as predictive biomarkers for acute AEs in response to external radiotherapy.

[Short- and medium-term tolerance of hypofractionated prostate radiotherapy with simultaneous integrated boost]

PURPOSE

This retrospective study was conducted to ensure that irradiation of the pelvic lymph node areas associated with simultaneous hypofractionated boost to the prostate according to the protocol implemented at the university hospital of Tours (France) does not result in excess urinary and digestive toxicity in the short and medium term.

MATERIALS AND METHODS

The study population included patients with localized unfavourable intermediate or high-risk prostate cancer. The dose delivered was 65Gy in 25 fractions of 2.6Gy to the prostate and seminal vesicles, and 50Gy in 25 fractions of 2Gy to the pelvic lymph nodes. Acute toxicity events (between the start of radiotherapy and the first follow-up consultation) and medium-term toxicity events (after the first follow-up consultation) were assessed using the CTCAE version 5.0 classification.

RESULTS

Sixty-three patients were treated according to the protocol between January 1st, 2020, and October 31st, 2022. The majority of them had high-risk prostate cancer (79%). The median follow-up was 15 months. Very few patients reported grade 3-4 toxicity acutely (6% urinary and 0% digestive toxicity) or in the medium term (7% urinary and 0% and digestive toxicity).

CONCLUSION

Radiotherapy of pelvic lymph node areas with simultaneous hypofractionated boost to the prostate is feasible, with low rates of severe acute and medium-term toxicity.

Case report: Intrafraction dose-guided tracking for gastrointestinal organ-at-risk isotoxicity delivery on an MR-guided radiotherapy system

In the current era of high-precision radiation therapy, real-time magnetic resonance (MR)-guided tracking of the tumor and organs at risk (OARs) is a novel approach that enables accurate and safe delivery of high-dose radiation. Organ tracking provides a general sense of the need for daily online adaptation but lacks precise information regarding exact dosimetry. To overcome this limitation, we developed the methodology for monitoring intrafraction motion with real-time MR-guided isodose line-based tracking of an OAR in combination with anatomic tumor-based tracking and reported the first case treated with this approach. An isolated para-aortic (PA) nodal recurrence from carcinosarcoma of the endometrium was treated with an ablative dose of 50 Gy in five fractions using MR-guided radiotherapy (MRgRT). This report demonstrates the feasibility, workflow, dosimetric constraints, and treatment paradigm for real-time isodose line-based OAR tracking and gating to enable an isotoxicity delivery approach. This innovative treatment strategy effectively tracked the intrafraction motion of both the target and OAR independently and enhanced the accuracy of structure localization in time and space with a more precise dosimetric evaluation.

Spatial Distribution of Recurrence and Long-Term Toxicity Following Dose Escalation to the Dominant Intra-Prostatic Nodule for Intermediate-High-Risk Prostate Cancer: Insights from a Phase I/II Study

Objectives: We investigated spatial patterns between primary and recurrent tumor sites and assessed long-term toxicity after dose escalation stereotactic body radiation therapy (SBRT) to the dominant intra-prostatic nodule (DIN). Materials and methods: In 33 patients with intermediate-high-risk prostate cancer (PCa), doses up to 50 Gy were administered to the DIN. Recurrence sites were determined and compared to the original tumor development sites through multiparametric MRI and 68Ga-labeled prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (68Ga-PSMA-PET/CT) images. Overlap rates, categorized as 75% or higher for full overlap, and 25-74% for partial overlap, were assessed. Long-term toxicity is reported. Results: All patients completed treatment, with only one receiving concomitant androgen deprivation therapy (ADT). Recurrences were diagnosed after a median of 33 months (range: 17-76 months), affecting 13 out of 33 patients (39.4%). Intra-prostatic recurrences occurred in 7 patients (21%), with ≥75% overlap in two, a partial overlap in another two, and no overlap in the remaining three patients. Notably, five patients with intra-prostatic recurrences had synchronous bone and/or lymph node metastases, while six patients had isolated bone or lymph node metastasis without intra-prostatic recurrences. Extended follow-up revealed late grade ≥ 2 GU and GI toxicity in 18% (n = 6) and 6% (n = 2) of the patients. Conclusions: Among patients with intermediate-high-risk PCa undergoing focal dose-escalated SBRT without ADT, DIN recurrences were infrequent. When present, these recurrences were typically located at the original site or adjacent to the initial tumor. Conversely, relapses beyond the DIN and in extra-prostatic (metastatic) sites were prevalent, underscoring the significance of systemic ADT in managing this patient population. Advances in knowledge: Focal dose-escalated prostate SBRT prevented recurrences in the dominant nodule; however, extra-prostatic recurrence sites were frequent.

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.

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.

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.

Prospective results for 5-year survival and toxicity of moderately hypofractionated radiotherapy with simultaneous integrated boost (SIB) in (very) high-risk prostate cancer

Purpose

High-risk (HR) prostate cancer patients usually receive high-dose radiotherapy (RT) using a two-phase sequential technique, but data on a simultaneous integrated boost (SIB) technique are lacking. We prospectively evaluated the long-term results of urinary (GU) and digestive (GI) toxicity and survival data for high-dose RT using a SIB technique in HR and very high-risk (VHR) prostate cancer.

Methods

Patients were treated using an SIB technique in 34 fractions, at a dose of 54.4 Gy to the pelvis and seminal vesicles and 74.8 Gy to the prostate, combined with 36 months of androgen-depriving therapy in a prospective multicenter study. Acute and late GU and GI toxicity data were collected. Overall survival (OS), biochemical-relapse-free survival (bRFS), loco-regional-relapse-free survival (LRRFS), metastasis-free-survival (MFS) and disease-free-survival (DFS) were assessed.

Results

We recruited 114 patients. After a median follow-up of 62 months, very few patients experienced acute (M0-M3) (G3-4 GU = 3.7 %; G3-4 GI = 0.9 %) or late (M6-M60) severe toxicity (G3-4 GU = 5.6 %; G3-4 GI = 2.8 %). The occurrence of acute G2 + GU or GI toxicity was significantly related to the consequential late G2 + toxicity (p < 0.01 for both GU and GI). Medians of OS, bRFS, LRRFS, MFS and DFS were not reached. At 60 months, OS, bRFS, LRRFS, MFS and DFS were 88.2 % [82.1; 94.7], 86.0 % [79.4 %;93.2 %], 95.8 % [91.8 %;99.9 %], 87.2 % [80.9 %;94.0 %] and 84.1 % [77.2 %;91.6 %] respectively.

Conclusion

SIB RT at a dose of 54.4 Gy to the pelvis and 74.8 Gy to the prostate is feasible, leading to satisfying tumor control and reasonable toxicity in HR and VHR prostate cancer.

Proton therapy for the management of localized prostate cancer: Long-term clinical outcomes at a comprehensive cancer center

BACKGROUND AND PURPOSE

Proton therapy (PT) has emerged as a standard-of-care treatment option for localized prostate cancer at our comprehensive cancer center. However, there are few large-scale analyses examining the long-term clinical outcomes. Therefore, this article aims to evaluate the long-term effectiveness and toxicity of PT in patients with localized prostate cancer.

MATERIALS AND METHODS

Review of 2772 patients treated from May 2006 through January 2020. Disease risk was stratified according to National Comprehensive Cancer Network guidelines as low [LR, n = 640]; favorable-intermediate [F-IR, n = 850]; unfavorable-intermediate [U-IR, n = 851]; high [HR, n = 315]; or very high [VHR, n = 116]. Biochemical failure and toxicity were analyzed using Kaplan-Meier estimates and multivariate models.

RESULTS

The median patient age was 66 years; the median follow-up time was 7.0 years. Pelvic lymph node irradiation was prescribed to 28 patients (1%) (2 [0.2%] U-IR, 11 [3.5%] HR, and 15 [12.9%] VHR). The median dose was 78 Gy in 1.8-2.0 Gy(RBE) fractions. Freedom from biochemical relapse (FFBR) rates at 5 years and 10 years were 98.2% and 96.8% for the LR group; 98.3% and 93.6%, F-IR; 94.2% and 90.2%, U-IR; 94.3% and 85.2%, HR; and 86.1% and 68.5%, VHR. Two patients died of prostate cancer. Overall rates of late grade ≥ 3 GU and GI toxicity were 0.87% and 1.01%.

CONCLUSIONS

Proton therapy for localized prostate cancer demonstrated excellent clinical outcomes in this large cohort, even among higher-risk groups with historically poor outcomes despite aggressive therapy.

Treatment outcomes of simultaneous integrated boost to intraprostatic lesions with external beam radiotherapy in localized prostate cancer patients

BACKGROUND

To evaluate the treatment outcomes and toxicity of definitive radiotherapy (RT) for prostate cancer (PC) patients using the simultaneous integrated boost (SIB) technique, which delivered 78 Gy to the entire prostate and 86 Gy to the intraprostatic lesion (IPL) in 39 fractions.

MATERIALS AND METHODS

Univariable and multivariable analyses were conducted of the prognostic factors for freedom from biochemical failure (FFBF), progression-free survival (PFS), and PC-specific survival (PCSS) of 619 PC patients who received definitive RT between September 2012 and August 2021. Predictors of late Grade ≥2 genitourinary (GU) and gastrointestinal (GI) toxicities were also identified using logistic regression.

RESULTS

The median follow-up for entire cohort was 68.5 months. The 5-year FFBF, PFS, and PCSS rates were 93.2%, 83.2%, and 98.6%, respectively. They were predicted by the serum prostate-specific antigen, Gleason score (GS), clinical nodal stage, and D'Amico risk group. Only 45 patients (7.3%) developed disease recurrence 41.9 months after RT. The 5-year FFBF rates for low-, intermediate-, and high-risk disease were 98.0%, 93.1%, and 88.5%, respectively (p < 0.001). The 5-year PFS and PCSS rates according to risk groups were 91.0%, 82.1%, and 77.4% (p < 0.001), and 99.2%, 96.4%, and 95.9% (p = 0.03), and, respectively. GS > 7 and lymph node metastasis negatively predicted FFBF and PCSS in multivariable analysis. Ninety (14.6%) and 44 (7.1%) patients had acute Grade ≥2 GU and GI toxicities, respectively, and 42 (6.8%) and 27 (4.4%) patients had late Grade ≥2 GU and GI toxicities, respectively. Diabetes and transurethral resection independently predicted late Grade 2 GU toxicity, but no significant predictor of late Grade ≥2 GI toxicity was found.

CONCLUSIONS

Localized PC was effectively and safely treated with definitive RT using the SIB technique to deliver 86 Gy to the IPL in 39 fractions without severe late toxicity. This finding must be validated with long-term results.

Toxicity of dose-escalated radiotherapy up to 84 Gy for prostate cancer

PURPOSE

The outcome of radiotherapy (RT) for prostate cancer (PCA) depends on the delivered dose. While the evidence for dose-escalated RT up to 80 gray (Gy) is well established, there have been only few studies examining dose escalation above 80 Gy. We initiated the present study to assess the safety of dose escalation up to 84 Gy.

METHODS

In our retrospective analysis, we included patients who received dose-escalated RT for PCA at our institution between 2016 and 2021. We evaluated acute genitourinary (GU) and gastrointestinal (GI) toxicity as well as late GU and GI toxicity.

RESULTS

A total of 86 patients could be evaluated, of whom 24 patients had received 80 Gy and 62 patients 84 Gy (35 without pelvic and 27 with pelvic radiotherapy). Regarding acute toxicities, no > grade 2 adverse events occurred. Acute GU/GI toxicity of grade 2 occurred in 12.5%/12.5% of patients treated with 80 Gy, in 25.7%/14.3% of patients treated with 84 Gy to the prostate only, and in 51.9%/12.9% of patients treated with 84 Gy and the pelvis included. Late GU/GI toxicity of grade ≥ 2 occurred in 4.2%/8.3% of patients treated with 80 Gy, in 7.1%/3.6% of patients treated with 84 Gy prostate only, and in 18.2%/0% of patients treated with 84 Gy pelvis included (log-rank test p = 0.358).

CONCLUSION

We demonstrated that dose-escalated RT for PCA up to 84 Gy is feasible and safe without a significant increase in acute toxicity. Further follow-up is needed to assess late toxicity and survival.

Fully automated segmentation of prostatic urethra for MR-guided radiation therapy

PURPOSE

Accurate delineation of the urethra is a prerequisite for urethral dose reduction in prostate radiotherapy. However, even in magnetic resonance-guided radiation therapy (MRgRT), consistent delineation of the urethra is challenging, particularly in online adaptive radiotherapy. This paper presented a fully automatic MRgRT-based prostatic urethra segmentation framework.

METHODS

Twenty-eight prostate cancer patients were included in this study. In-house 3D half fourier single-shot turbo spin-echo (HASTE) and turbo spin echo (TSE) sequences were used to image the Foley-free urethra on a 0.35 T MRgRT system. The segmentation pipeline uses 3D nnU-Net as the base and innovatively combines ground truth and its corresponding radial distance (RD) map during training supervision. Additionally, we evaluate the benefit of incorporating a convolutional long short term memory (LSTM-Conv) layer and spatial recurrent convolution layer (RCL) into nnU-Net. A novel slice-by-slice simple exponential smoothing (SEPS) method specifically for tubular structures was used to post-process the segmentation results.

RESULTS

The experimental results show that nnU-Net trained using a combination of Dice, cross-entropy and RD achieved a Dice score of 77.1 ± 2.3% in the testing dataset. With SEPS, Hausdorff distance (HD) and 95% HD were reduced to 2.95 ± 0.17 mm and 1.84 ± 0.11 mm, respectively. LSTM-Conv and RCL layers only minimally improved the segmentation precision.

CONCLUSION

We present the first Foley-free MRgRT-based automated urethra segmentation study. Our method is built on a data-driven neural network with novel cost functions and a post-processing step designed for tubular structures. The performance is consistent with the need for online and offline urethra dose reduction in prostate radiotherapy.

Rectal retractor in prostate radiotherapy: pros and cons

Dose escalation in prostate radiotherapy (RT) have led to improved biochemical controls and reduced the risk of distant metastases. Over the past three decades, despite technological advancements in RT planning and delivery, the rectum is a dose-limiting structure in prostate RT owing to the close anatomical proximity of the anterior rectal wall (ARW) to the prostate gland. RT-induced rectal toxicities remain a clinical challenge, limiting the prescribed dose during prostate RT. To address the spatial proximity challenge by physically increasing the distance between the posterior aspect of the prostate and the ARW, several physical devices such as endorectal balloons (ERBs), rectal hydrogel spacers, and rectal retractor (RR) have been developed. Previously, various aspects of ERBs and rectal hydrogel spacers have extensively been discussed. Over recent years, given the interest in the application of RR in prostate external beam radiotherapy (EBRT), this editorial will discuss opportunities and challenges of using RR during prostate EBRT and provide information regarding which aspects of this device need attention.

Single dose Tadalafil 5 mg in Muscle Invasive Bladder Cancer (MIBC) patient induce priapism: A case report and literature review

There are several etiology related to priapism with incidence is less than 0.01%. A 47-year-old man was referred to our Emergency Room with a chief complaint of persistent and painful erection for 3 days. Previously, the patient took Tadalafil 5 mg to overcome the complaints of erectile dysfunction that he felt after undergoing (TURBT) and external radiation treatment. The patient treated with epinephrine injection and distal shunting surgical procedure Minimal and single dose of tadalafil can cause priapism as in this case. Time interval between onset and therapy affect patient outcome.

Long-term outcomes of prostate intensity-modulated radiation therapy incorporating a simultaneous intra-prostatic MRI-directed boost

Purpose/objectives

This retrospective study demonstrates the long-term outcomes of treating prostate cancer using intensity modulated (IMRT) with incorporation of MRI-directed boost.

Materials/methods

From February 2009 to February 2013, 78 men received image-guided IMRT delivering 77.4 Gy in 44 fractions with simultaneously integrated boost to 81-83 Gy to an MRI-identified lesion. Patients with intermediate-risk or high-risk prostate cancer were recommended to receive 6 and 24-36 months of adjuvant hormonal therapy, respectively.

Results

Median follow-up was 113 months (11-147). There were 18 low-risk, 43 intermediate-risk, and 17 high-risk patients per NCCN risk stratification included in this study. Adjuvant hormonal therapy was utilized in 32 patients (41%). The 10-year biochemical control rate for all patients was 77%. The 10-year biochemical control rates for low-risk, intermediate-risk, and high-risk diseases were 94%, 81%, and 88%, respectively (p = 0.35). The 10-year rates of local control, distant control, and survival were 99%, 88%, and 66%, respectively. Of 25 patients who died, only four (5%) died of prostate cancer. On univariate analysis, T-category and pretreatment PSA level were associated with distant failure rate (p = 0.02). There was no grade =3 genitourinary and gastrointestinal toxicities that persisted at the last follow-up.

Conclusions

This study demonstrated the long-term efficacy of using MRI to define an intra-prostatic lesion for SIB to 81-83Gy while treating the entire prostate gland to 77.4 Gy with IMRT. Our study confirms that modern MRI can be used to locally intensify dose to prostate tumors providing high long-term disease control while maintaining favorable long-term toxicity.

External radiotherapy for prostatic cancers

We present the update of the recommendations of the French society of oncological radiotherapy on external radiotherapy of prostate cancer. External radiotherapy is intended for all localized prostate cancers, and more recently for oligometastatic prostate cancers. The irradiation techniques are detailed. Intensity-modulated radiotherapy combined with prostate image-guided radiotherapy is the recommended technique. A total dose of 74 to 80Gy is recommended in case of standard fractionation (2Gy per fraction). Moderate hypofractionation (total dose of 60Gy at a rate of 3Gy per fraction over 4 weeks) in the prostate has become a standard of therapy. Simultaneous integrated boost techniques can be used to treat lymph node areas. Extreme hypofractionation (35 to 40Gy in five fractions) using stereotactic body radiotherapy can be considered a therapeutic option to treat exclusively the prostate. The postoperative irradiation technique, indicated mainly in case of biological recurrence and lymph node involvement, is detailed.

Bladder surface dose modeling in prostate cancer radiotherapy: An analysis of motion-induced variations and the cumulative dose across the treatment

PURPOSE

To introduce a novel surface-based dose mapping method to improve quantitative bladder dosimetric assessment in prostate cancer (PC) radiotherapy.

METHODS

Based on the planning and daily pre and postfraction MRIs of 12 PC patients, bladder surface models (SMs) were generated on manually delineated contours and regionally aligned via surface-based registration. Subsequently, bladder surface dose models (SDMs) were created using face-wise dose sampling. To determine the bladder intrafractional and interfractional motion and dose variation, we performed a pose analysis between pre and postfraction bladder SMs, as well as surface mapping for fractional SMs. Discrepancies between the received dose, accumulated from daily SDMs, and the planned dose were then assessed on the corresponding SDMs. Complementary to the surface dose mapping, dose surface histogram (DSH)-based comparisons were also performed.

RESULTS

The intrafraction pose analysis revealed a significant (p < 0.05) bladder expansion, as well as an anterior/superior drift during the treatment. The intrafraction motion substantially altered dose to mid-bladder body, but not the bladder surface areas distal to or contiguous with the target. A similar pattern of dose variations was also detected by interfraction comparisons. With surface registration to the common SM, the cumulative bladder dose significantly differs from the planned dose. The discrepancy is evident in the mid-posterior range that corresponds to a mid- to high-dose region. The received DSH significantly differs from the planned DSH after permutation correction (p = 0.0122), while the overall surface-based comparison after multiple comparison correction is nonsignificant (p = 0.0800).

CONCLUSIONS

We developed a novel surface-based intra and interdose mapping framework applied to a unique daily MR dataset for image-guided radiotherapy. The framework identified significant intrafraction bladder positional changes, localized the intra and interfraction variations, and quantified planned versus received dose differences on the bladder surface. The result indicates the importance of adopting the motion-integrated bladder SDM for bladder dose management.

Ten Year Results of Extensive Nodal Radiotherapy and Moderately Hypofractionated Simultaneous Integrated Boost in Unfavorable Intermediate-, High-, and Very High-Risk Prostate Cancer

Simple Summary

Several phase III randomized trials of moderate hypofractionation, including a higher proportion of high-risk prostate cancer patients treated only to the prostate, failed to demonstrate the superiority of hypofractionated regimens. There is only one randomized phase III trial, of moderately hypofractionated high-dose radiotherapy to the prostate-only versus pelvic irradiation and prostate boost, with a sufficiently long follow-up. It demonstrated better biochemical and disease-free survival when lymph nodal radiotherapy was added. Here we present the 10-year results of our experience based on an Institutional protocol adopted after a phase I–II study, on patients with unfavorable intermediate- (UIR), high- (HR), and very high-risk (VHR) prostate cancer (PCa) treated with pelvic lymph nodal irradiation (WPRT) and moderately hypofractionated high-dose (HD) simultaneous integrated boost (SIB) to the prostate. Prognostic factors for relapse, as well as acute and late gastro-intestinal (GI) and genito-urinary (GU) toxicity were also analyzed.

Abstract

Aims: To report 10-year outcomes of WPRT and HD moderately hypofractionated SIB to the prostate in UIR, HR, and VHR PCa. Methods: From 11/2005 to 12/2015, 224 UIR, HR, and VHR PCa patients underwent WPRT at 51.8 Gy/28 fractions and SIB at 74.2 Gy (EQD2 88 Gy) to the prostate. Androgen deprivation therapy (ADT) was prescribed in up to 86.2% of patients. Results: Median follow-up was 96.3 months (IQR: 71–124.7). Median age was 75 years (IQR: 71.3–78.1). At last follow up, G3 GI–GU toxicity was 3.1% and 8%, respectively. Ten-year biochemical relapse-free survival (bRFS) was 79.8% (95% CI: 72.3–88.1%), disease-free survival (DFS) 87.8% (95% CI: 81.7–94.3%), overall survival (OS) 65.7% (95% CI: 58.2–74.1%), and prostate cancer-specific survival (PCSS) 94.9% (95% CI: 91.0–99.0%). Only two patients presented local relapse. At univariate analysis, VHR vs. UIR was found to be a significant risk factor for biochemical relapse (HR: 2.8, 95% CI: 1.17–6.67, p = 0.021). After model selection, only Gleason Score ≥ 8 emerged as a significant factor for biochemical relapse (HR = 2.3, 95% CI: 1.12–4.9, p = 0.023). Previous TURP (HR = 3.5, 95% CI: 1.62–7.54, p = 0.001) and acute toxicity ≥ G2 (HR = 3.1, 95% CI = 1.45–6.52, p = 0.003) were significant risk factors for GU toxicity ≥ G3. Hypertension was a significant factor for GI toxicity ≥ G3 (HR = 3.63, 95% CI: 1.06–12.46, p = 0.041). ADT (HR = 0.31, 95% CI: 0.12–0.8, p = 0.015) and iPsa (HR = 0.37, 95% CI: 0.16–0.83, p = 0.0164) played a protective role. Conclusions: WPRT and HD SIB to the prostate combined with long-term ADT, in HR PCa, determine good outcomes with acceptable toxicity.

Retrospective comparison of rectal toxicity between carbon-ion radiotherapy and intensity-modulated radiation therapy based on treatment plan, normal tissue complication probability model, and clinical outcomes in prostate cancer

This retrospective study assessed the treatment planning data and clinical outcomes for 152 prostate cancer patients: 76 consecutive patients treated by carbon-ion radiation therapy and 76 consequtive patients treated by moderate hypo-fractionated intensity-modulated photon radiation therapy. These two modalities were compared using linear quadratic model equivalent doses in 2 Gy per fraction for rectal or rectal wall dose-volume histogram, 3.6 Gy per fraction-converted rectal dose-volume histogram, normal tissue complication probability model, and actual clinical outcomes. Carbon-ion radiation therapy was predicted to have a lower probability of rectal adverse events than intensity-modulated photon radiation therapy based on dose-volume histograms and normal tissue complication probability model. There was no difference in the clinical outcome of rectal adverse events between the two modalities compared in this study.

Clinical predictors of severe late urinary toxicity after curative intensity-modulated radiation therapy for localized prostate cancer

Intractable late urinary toxicity is a serious complication after radiotherapy for patients with localized prostate cancer (LPC). We assessed clinical factors correlated with severe late urinary toxicity in LPC treated with curative image-guided intensity-modulated radiation therapy (IMRT). A total of 452 patients with LPC treated with IMRT between 2002 and 2016 were retrospectively analyzed. Among them, 432 patients received androgen deprivation therapy (ADT). The median total irradiated doses were 80 (range, 76-80) Gy. Each daily dose was 2 Gy per fraction. The median follow-up was 83 (range, 4-210) months. Late urinary toxicity was scored according to the National Cancer Institute Common Terminology Criteria for Adverse Events, Version 4.03. Grade 3 late urinary toxicity was observed in 27 patients. No cases with grade ≥ 4 late urinary toxicity were observed. The 5-, 10-, and 12.5-year grade 3 late urinary toxicity-free survival rates were 97%, 91.8% and 88.1%, respectively. Age, risk classification, total irradiated dose, ADT duration, antithrombotic therapy (AT), cardiovascular disease, hypertension (HT), diabetes mellitus (DM), dyslipidemia (DL), prior transurethral resection of the prostate (TURP) and prior high-intensity focused ultrasound (HIFU) were investigated for correlations with grade 3 late urinary toxicity. In univariate analysis, AT and prior HIFU and no other studied factors, were correlated with grade 3 late urinary toxicity. AT and prior HIFU appear to be predictive of grade 3 late urinary toxicity. Patients with LPC with these relevant clinical factors should be carefully followed up by sharing detailed information with the urology department.

Risk Factors of Biochemical Failure in Locally Advanced Carcinoma Prostate Treated With Definitive External Beam Radiotherapy and Androgen Deprivation Therapy: Experience From Tertiary Care Center in North India

Background Locally advanced prostate cancer (LACAP), despite external beam radiotherapy (EBRT) along with antiandrogen therapy (ADT) has risk of prostate-specific antigen (PSA) progression. Furthermore, number of studies have emphasized on different prognostic factors. The purpose of our study is to analyze risk factors for biochemical failure (BF) in these patients treated at our institute. Methods Our study is a single-institution retrospective observational done at a tertiary care center in North India. Between January 2018 and December 2020, we retrospectively identified 34 patients managed at our institute as per multidisciplinary board (MBD). Demographic, clinical, radiological, pathological and treatment-related parameters were assessed as potential risk factors. End-point of the study was to find significant risk factors for BF. Statistical analysis was done on SPSS, version 20 (IBM Corp., Armonk, NY). Results All eligible patients received EBRT with ADT as per institution policy. Mean follow-up period was 20 months during which two (5.9%) patients had BF at a mean of 30 months after EBRT. Four-year PSA-progression-free survival rate was 73%. On univariate analysis, prognostic factors associated with high risk of BF were Gleason score and clinical T stage. Conclusion In summary, prognostic factors for high risk of BF leading to clinical progression are Gleason score 9 or 10 and clinical T3b stage.

The 2019 Genitourinary Pathology Society (GUPS) White Paper on Contemporary Grading of Prostate Cancer

CONTEXT.—

Controversies and uncertainty persist in prostate cancer grading.

OBJECTIVE.—

To update grading recommendations.

DATA SOURCES.—

Critical review of the literature along with pathology and clinician surveys.

CONCLUSIONS.—

Percent Gleason pattern 4 (%GP4) is as follows: (1) report %GP4 in needle biopsy with Grade Groups (GrGp) 2 and 3, and in needle biopsy on other parts (jars) of lower grade in cases with at least 1 part showing Gleason score (GS) 4 + 4 = 8; and (2) report %GP4: less than 5% or less than 10% and 10% increments thereafter. Tertiary grade patterns are as follows: (1) replace "tertiary grade pattern" in radical prostatectomy (RP) with "minor tertiary pattern 5 (TP5)," and only use in RP with GrGp 2 or 3 with less than 5% Gleason pattern 5; and (2) minor TP5 is noted along with the GS, with the GrGp based on the GS. Global score and magnetic resonance imaging (MRI)-targeted biopsies are as follows: (1) when multiple undesignated cores are taken from a single MRI-targeted lesion, an overall grade for that lesion is given as if all the involved cores were one long core; and (2) if providing a global score, when different scores are found in the standard and the MRI-targeted biopsy, give a single global score (factoring both the systematic standard and the MRI-targeted positive cores). Grade Groups are as follows: (1) Grade Groups (GrGp) is the terminology adopted by major world organizations; and (2) retain GS 3 + 5 = 8 in GrGp 4. Cribriform carcinoma is as follows: (1) report the presence or absence of cribriform glands in biopsy and RP with Gleason pattern 4 carcinoma. Intraductal carcinoma (IDC-P) is as follows: (1) report IDC-P in biopsy and RP; (2) use criteria based on dense cribriform glands (>50% of the gland is composed of epithelium relative to luminal spaces) and/or solid nests and/or marked pleomorphism/necrosis; (3) it is not necessary to perform basal cell immunostains on biopsy and RP to identify IDC-P if the results would not change the overall (highest) GS/GrGp part per case; (4) do not include IDC-P in determining the final GS/GrGp on biopsy and/or RP; and (5) "atypical intraductal proliferation (AIP)" is preferred for an intraductal proliferation of prostatic secretory cells which shows a greater degree of architectural complexity and/or cytological atypia than typical high-grade prostatic intraepithelial neoplasia, yet falling short of the strict diagnostic threshold for IDC-P. Molecular testing is as follows: (1) Ki67 is not ready for routine clinical use; (2) additional studies of active surveillance cohorts are needed to establish the utility of PTEN in this setting; and (3) dedicated studies of RNA-based assays in active surveillance populations are needed to substantiate the utility of these expensive tests in this setting. Artificial intelligence and novel grading schema are as follows: (1) incorporating reactive stromal grade, percent GP4, minor tertiary GP5, and cribriform/intraductal carcinoma are not ready for adoption in current practice.

Magnetic resonance imaging-guided stereotactic body radiotherapy for prostate cancer (mirage): a phase iii randomized trial

Background

Stereotactic body radiotherapy (SBRT) is becoming increasingly used in treating localized prostate cancer (PCa), with evidence showing similar toxicity and efficacy profiles when compared with longer courses of definitive radiation. Magnetic resonance imaging (MRI)-guided radiotherapy has multiple potential advantages over standard computed tomography (CT)-guided radiotherapy, including enhanced prostate visualization (abrogating the need for fiducials and MRI fusion), enhanced identification of the urethra, the ability to track the prostate in real-time, and the capacity to perform online adaptive planning. However, it is unknown whether these potential advantages translate into improved outcomes. This phase III randomized superiority trial is designed to prospectively evaluate whether toxicity is lower after MRI-guided versus CT-guided SBRT.

Methods

Three hundred men with localized PCa will be randomized in a 1:1 ratio to SBRT using CT or MRI guidance. Randomization will be stratified by baseline International Prostate Symptom Score (IPSS) (≤15 or > 15) and prostate gland volume (≤50 cc or > 50 cc). Five fractions of 8 Gy will be delivered to the prostate over the course of fourteen days, with or without hormonal therapy and elective nodal radiotherapy (to a dose of 5 Gy per fraction) as per the investigator’s discretion. The primary endpoint is the incidence of physician-reported acute grade ≥ 2 genitourinary (GU) toxicity (during the first 90 days after SBRT), as assessed by the CTCAE version 4.03 scale. Secondary clinical endpoints include incidence of acute grade ≥ 2 gastrointestinal (GI) toxicity, 5-year cumulative incidences of physician-reported late grade ≥ 2 GU and GI toxicity, temporal changes in patient-reported quality of life (QOL) outcomes, 5-year biochemical recurrence-free survival and the proportion of fractions of MRI-guided SBRT in which online adaptive radiotherapy is used.

Discussion

The MIRAGE trial is the first randomized trial comparing MRI-guided with standard CT-guided SBRT for localized PCa. The primary hypothesis is that MRI-guided SBRT will lead to an improvement in the cumulative incidence of acute grade ≥ 2 GU toxicity when compared to CT-guided SBRT. The pragmatic superiority design focused on an acute toxicity endpoint will allow an early comparison of the two technologies.

Trial registration

Clinicaltrials.gov identifier: NCT04384770. Date of registration: May 12, 2020.

https://clinicaltrials.gov/ct2/show/NCT04384770

Protocol version

Version 2.1, Aug 28, 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08281-x.

Dosimetric impact of rectum and bladder anatomy and intrafractional prostate motion on hypofractionated prostate radiation therapy

OBJECTIVE

The objective of this study was to evaluate the dosimetric impact on hypofractionated prostate radiation therapy of two geometric uncertainty sources: rectum and bladder filling and intrafractional prostate motion.

MATERIALS AND METHODS

This prospective study included 544 images (375 pre-treatment cone-beam CT [CBCT] and 169 post-treatment CBCT) from 15 prostate adenocarcinoma patients. We recalculated the dose on each pre-treatment CBCT once the positioning errors were corrected. We also recalculated two dose distributions on each post-treatment CBCT, either using or not intrafractional motion correction. A correlation analysis was performed between CBCT-based dose and rectum and bladder filling as well as intrafraction prostate displacements.

RESULTS

No significant differences were found between administered and planned rectal doses. However, we observed an increase in bladder dose due to a lower bladder filling in 66% of treatment fractions. These differences were reduced at the end of the fraction since the lower bladder volume was compensated by the filling during the treatment session. A statistically significant reduction in target volume coverage was observed in 27% of treatment sessions and was correlated with intrafractional prostate motion in sagittal plane > 4 mm.

CONCLUSIONS

A better control of bladder filling is recommended to minimize the number of fractions in which the bladder volume is lower than planned. Fiducial mark tracking with a displacement threshold of 5 mm in any direction is recommended to ensure that the prescribed dose criteria are met.

Dosimetric and clinical outcomes of SpaceOAR in men undergoing external beam radiation therapy for localized prostate cancer: A systematic review

SpaceOAR, an absorbable polyethylene glycol hydrogel, increases the space between the prostate and rectum to reduce the radiation received by the rectum during prostate cancer radiation therapy. The objective of this systematic review was to evaluate controlled studies on the dosimetric and clinical outcomes of SpaceOAR in men undergoing external beam radiation therapy for localized prostate cancer. Eight studies were included in the review. All of the studies showed SpaceOAR to reduce the radiation dose volume to the rectum over numerous dosimetry levels. Of the four studies that assessed toxicity, one reported SpaceOAR to significantly decrease acute Grade 1 diarrhoea and two reported SpaceOAR to significantly decrease late Grade 1 and Grade ≥2 rectal toxicities. Two studies assessed cumulative incidence of toxicity at 3 years in which one reported SpaceOAR to significantly decrease urinary incontinence and Grade ≥1 and Grade ≥2 rectal toxicities, and the other reported SpaceOAR to significantly decrease Grade 1 diarrhoea and Grade 2 proctitis. Moreover, one study reported that fewer SpaceOAR patients experienced 10-point declines in bowel quality of life at 3 years, but another study reported no significant difference in 10-point declines in bowel quality of life between the SpaceOAR and control groups at 5 years. With the current research available, SpaceOAR may be beneficial to those who did not meet the standard rectal dose-volume criteria, have higher risk factors of developing rectal toxicities post-radiation, or wish to decrease the length and costs of radiotherapy by increasing the dose of radiation per fraction.

Consensus Statement on Proton Therapy for Prostate Cancer

Proton therapy is a promising but controversial treatment in the management of prostate cancer. Despite its dosimetric advantages when compared with photon radiation therapy, its increased cost to patients and insurers has raised questions regarding its value. Multiple prospective and retrospective studies have been published documenting the efficacy and safety of proton therapy for patients with localized prostate cancer and for patients requiring adjuvant or salvage pelvic radiation after surgery. The Particle Therapy Co-Operative Group (PTCOG) Genitourinary Subcommittee intends to address current proton therapy indications, advantages, disadvantages, and cost effectiveness. We will also discuss the current landscape of clinical trials. This consensus report can be used to guide clinical practice and research directions.

Hypofractionated versus conventionally fractionated image-guided volumetric-modulated arc radiotherapy for localized prostate cancer: a phase II randomized trial from China

Purpose: To determine the safety of hypofractionated imaging-guided (IG) volumetric-modulated arc radiotherapy (IG-VMAT; 70 Gy/28 fractions over 5.5 weeks) versus conventionally fractionated regimen (IG-VMAT; 80 Gy/40 fractions over 8 weeks) in Chinese patients with localized prostate cancer.

Method: In this randomized non-comparative phase II trial, 92 patients with localized prostate cancer were assigned to receive either hypofractionated IG-VMAT (HFRT; 70 Gy/2.5Gy/28f) or conventionally fractionated IG-VMAT (CFRT; 80 Gy/2Gy/40f). Primary endpoint was grade 2 or higher late gastrointestinal (GI) and genitourinary (GU) toxicity at 2 years. The GI/GU toxicity and biochemical relapse–free survival (bRFS) were compared between the two treatment groups.

Results: Median follow-up was 26 months. The incidence of grade 2 or higher late GI/GU toxicity was low in both groups; the 5-year cumulative incidence of Radiation Therapy Oncology Group grade 2 or higher GI/GU toxicity at 2 years was 7.6% with HFRT versus 10.3% with CFRT (P = 0.707). Biochemical control was not significantly different between the two groups; the 2-year bRFS was 94.6% for HFRT versus 95.0% for CFRT (P = 0.704).

Conclusion: Hypofractionated IG-VMAT appears to be equivalent to conventionally fractionated IG-VMAT in terms of toxicity in Chinese patients with localized prostate cancer.

Clinical iterative model development improves knowledge-based plan quality for high-risk prostate cancer with four integrated dose levels

BACKGROUND

Manual volumetric modulated arc therapy (VMAT) treatment planning for high-risk prostate cancer receiving whole pelvic radiotherapy (WPRT) with four integrated dose levels is complex and time consuming. We have investigated if the radiotherapy planning process and plan quality can be improved using a well-tuned model developed through a commercial system for knowledge-based planning (KBP).

MATERIAL AND METHODS

Treatment plans from 69 patients treated for high-risk prostate cancer with manually planned VMAT were used to develop an initial KBP model (RapidPlan, RP). Prescribed doses were 50, 60, 67.5, and 72.5 Gy in 25 fractions to the pelvic lymph nodes, prostate and seminal vesicles, prostate gland, and prostate tumour(s), respectively. This RP model was in clinical use from July 2019 to February 2020, producing another set of 69 clinically delivered treatment plans for a new patient group, which were used to develop a second RP model. Both models were validated on an independent group of 40 patients. Plan quality was compared by D _98% and the Paddick conformity index for targets, mean dose (D _mean) and generalised equivalent uniform dose (gEUD) for bladder, bowel bag and rectum, and number of monitor units (MU).

RESULTS

Target coverage and conformity was similar between manually created and RP treatment plans. Compared to the manually created treatment plans, the final RP model reduced average D _mean and gEUD with 2.7 Gy and 1.3 Gy for bladder, 1.2 Gy and 0.9 Gy for bowel bag, and 2.7 Gy and 0.8 Gy for rectum, respectively (p < .05). For rectum, the interpatient variation (i.e., 95% confidence interval) of DVHs was reduced by 23%.

CONCLUSION

KBP improved plan quality and consistency among treatment plans for high-risk prostate cancer. Model tuning using KBP-based clinical plans further improved model outcome.

Brachytherapy boost (BT-boost) or stereotactic body radiation therapy boost (SBRT-boost) for high-risk prostate cancer (HR-PCa)

Systematic review for the treatment of high-risk prostate cancer (HR-PCa, D'Amico classification risk system) with external body radiation therapy (EBRT)+brachytherapy-boost (BT-boost) or with EBRT+stereotactic body RT-boost (SBRT-boost). In March 2020, 391 English citations on PubMed matched with search terms "high risk prostate cancer boost". Respectively 9 and 48 prospective and retrospective studies were on BT-boost and 7 retrospective studies were on SBRT-boost. Two SBRT-boost trials were prospective. Only one study (ASCENDE-RT) directly compared the gold standard treatment [dose-escalation (DE)-EBRT+androgen deprivation treatment (ADT)] versus EBRT+ADT+BT-boost. Biochemical control rates at 9 years were 83% in the experimental arm versus 63% in the standard arm. Cumulative incidence of late grade 3 urinary toxicity in the experimental arm and in the standard arm was respectively 18% and 5%. Two recent studies with HR-PCa (National Cancer Database) demonstrated better overall survival with BT-boost (low dose rate LDR or high dose rate HDR) compared with DE-EBRT. These recent findings demonstrate the superiority of EBRT+BT-boost+ADT versus DE-EBRT+ADT for HR-PCa. It seems that EBRT+BT-boost+ADT could now be considered as a gold standard treatment for HR-PCa. HDR or LDR are options. SBRT-boost represents an attractive alternative, but the absence of randomised trials does not allow us to conclude for HR-PCa. Prospective randomised international phase III trials or meta-analyses could improve the level of evidence of SBRT-boost for HR-PCa.

Markers of Toxicity and Response to Radiation Therapy in Patients With Prostate Cancer

The main treatment modalities for localized prostate cancer are surgery and radiation. Surgery removes the whole prostate gland, whereas with radiation therapy the irradiated prostate remains within the patient's body. Biomarkers specific to the prostate gland should become undetectable after surgery, but this is not the case when radiation therapy is used, as residual prostate cells may still be metabolically active. Here, we review the role of tumor markers of toxicity and response to radiation therapy in patients with prostate cancer, including prostate specific antigen, human kallikrein 2, osteopontin, prostate cancer associated 3, citrulline, and others.

Hypofractionated Radiation Therapy to the Prostate Bed With Intensity-Modulated Radiation Therapy (IMRT): A Phase 2 Trial

PURPOSE

Postoperative radiation therapy (RT) is a common therapy used for patients with prostate cancer. Although clinical trials have established the safety and efficacy of hypofractionation as a primary therapy, there are limited data in a postoperative setting. We conducted a prospective trial to evaluate the safety and feasibility of postoperative hypofractionated RT to the prostate bed.

METHODS AND MATERIALS

In this phase 2 trial, patients submitted to radical prostatectomy were treated with hypofractionated RT to the prostate bed (adjuvant or salvage). The prescribed dose was 51 Gy in 15 fractions (3.4 Gy per fraction), using intensity modulated and image guided radiation therapy techniques. The primary endpoint was the rate of acute genitourinary (GU) grade ≥2 toxicity. Secondary endpoints included acute gastrointestinal (GI) and late GU/GI toxicities, biochemical failure-free survival (BFFS), metastasis-free survival, cancer-specific survival, overall survival, and health-related quality of life.

RESULTS

Of 64 enrolled patients, 61 received radiation therapy (57 salvage and 4 adjuvant radiation therapy). After a median follow-up of 16 months, 11.5% of patients experienced acute grade ≥2 GU symptoms and 13.1% experienced acute grade ≥2 GI symptoms. The late grade ≥2 GU toxicity rate was 8.2%, and 1 patient (1.6%) developed both acute and late grade 3 GU toxicity. The late grade ≥2 GI toxicity rate was 11.5%, and no grade 3 GI adverse events were reported. The short follow-up limits our ability to perform a robust oncologic endpoint assessment; however, the 2-year BFFS, use of subsequent salvage therapy, and the development of metastasis were 95.1%, 0%, and 0%, respectively.

CONCLUSIONS

Hypofractionated RT to the prostate bed in 15 treatments was safe, with an acceptable GU and GI toxicity profile. Further study in large, randomized trials is warranted.

Absence of prostate oedema obviates the need for delay between fiducial marker insertion and radiotherapy simulation

INTRODUCTION

Fiducial markers (FMs) are commonly inserted into the prostate for image guided radiation therapy. This study aimed to quantify prostate oedema immediately following FM insertion compared to prostate volumes measured a week later, at the time of simulation for radiation therapy.

METHODS

Thirty patients underwent a verification computed tomography (VCT) scan in treatment position immediately after the fiducial insertion and their planning computed tomography scan (PCT) one week after. Patient data sets were retrospectively evaluated, comparing prostate volumes and planning target volumes (PTV). Volumes were delineated by a single radiation oncologist, blinded to whether the scan was VCT or PCT. Distances between the FMs were measured on both scans. Descriptive statistics described the data, DICE similarity co-efficient (DSC) calculated, and paired t-tests were used to compare paired data.

RESULTS

The median prostate volume was 35.09 cc and 36.31 cc for VCT and PCT data sets, respectively, and median PTV was 118.56 cc and 127.04 cc for VCT and PCT, respectively. There was no significant difference in prostate volumes (P = 0.3037) or PTV (P = 0.1279), with a DSC of 0.87 (range 0.76-0.91) and 0.91 (range 0.85 to 0.95), respectively. Similarly, there was no significant difference in distance between fiducial markers (P > 0.05).

CONCLUSION

This study demonstrates no statistically significant difference in prostate or PTV volumes (P > 0.05) between the CT acquired at fiducial marker insertion compared with the CT acquired a week later. Therefore, oedema is not significant enough to justify a delay between FM insertion and simulation.

Proton Therapy for Localized Prostate Cancer: Long-Term Results From a Single-Center Experience

PURPOSE

Although proton therapy is controversial, it has been used to treat localized prostate cancer over the past 2 decades. The purpose of this study is to examine the long-term efficacy and toxicity of proton therapy for localized prostate cancer.

METHODS AND MATERIALS

This was a retrospective observational study of 2021 patients from 2003 to 2014 at a single institution. Patients were classified using the risk groups defined by the National Comprehensive Cancer Network guidelines, version 4.2019. Ninety-eight percent of the patients received 74 Gy (relative biological effectiveness) in 37 fractions. Fifty-one and 6% of the patients received neoadjuvant and adjuvant androgen deprivation therapy, respectively. The outcomes were the time of freedom from biochemical relapse and the time to late toxicity by the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. The outcomes were estimated using the Kaplan-Meier method and were analyzed using multivariable Cox proportional hazards models.

RESULTS

The median follow-up period was 84 months (interquartile range, 60-110). The 5- and 10-year freedom from biochemical relapse rates were 100% and 100%, 99% and 88%, 93% and 86%, 90% and 79%, 88% and 68%, and 76% and 63% for the very low, low, favorable intermediate, unfavorable intermediate, high, and very high-risk groups, respectively. Patients with higher risk experienced biochemical relapse after shorter periods. The 5-year rates of grade 2 or higher late genitourinary and gastrointestinal toxicity were 2.2% and 4.0%, respectively. The results of multivariable analyses indicate that younger patients more often experienced biochemical relapse.

CONCLUSIONS

This study demonstrates the favorable biochemical controls of proton therapy even in advanced localized prostate cancer patients with a low incidence of late toxicities, supporting the feasibility of conducting prospective clinical trials. The risk groups defined by the National Comprehensive Cancer Network guidelines, version 4.2019, are useful to classify patients with localized prostate cancer. Our findings might suggest the necessity to develop a treatment strategy that accounts for the patient's age.

National survey of radiation oncologists' practice patterns regarding hormone-naïve prostate cancer with bone metastases

OBJECTIVE

To explore radiation oncologists' attitudes and practice patterns of radiotherapy for hormone-naïve prostate cancer with bone metastases in Japan.

METHODS

An internet-based survey was distributed to board-certified radiation oncologists of the Japanese Society of Radiation Oncology. Three hypothetical cases were assumed: hormone-naïve prostate cancer with single, three or multiple non-symptomatic bone metastases. The respondents described their attitude regarding such cases, treatment methods and the radiotherapy dose fractionation that they would recommend.

RESULTS

Among the 1013 board-certified radiation oncologists in Japan, 373 (36.8%) responded to the questionnaire. Most of the respondents (85.0%) believed that radiotherapy may be applicable as a primary treatment for hormone-naïve prostate cancer with bone metastases in some circumstances. For Case 1 (single bone metastasis), 55.0% of the respondents recommended radiotherapy for the prostate and bone metastasis. For Case 2 (three bone metastases), only 24.4% recommended radiotherapy for all lesions, and 31.4% recommended radiotherapy for the prostate only. For Case 3 (multiple bone metastases), 49.1% of the respondents stated that there was no indication for radiotherapy. However, 34% of the respondents still preferred to administer radiotherapy for the prostate. The radiotherapy techniques and dose fractionations varied widely among the respondents.

CONCLUSION

Most of the respondent radiation oncologists believed that radiotherapy may be beneficial for hormone-naïve prostate cancer with bone metastases.

Management of Isolated Local Failures Following Stereotactic Body Radiation Therapy for Low to Intermediate Risk Prostate Cancer

Background: Stereotactic body radiation therapy (SBRT) is a safe and effective treatment option for patients with low to intermediate risk prostate cancer (1). SBRT results in very low PSA nadirs secondary to the delivery of high biologically effective doses. Studies reporting on the diagnosis, confirmation, and management of salvageable isolated local failures (ILF) are limited. This study aims to determine the incidence and management approach of ILF after SBRT in a large single institution cohort. Method: All patients with low or intermediate risk localized prostate cancer treated with SBRT at Georgetown University Hospital were eligible for this study. Treatment was delivered using robotic SBRT with doses of 35-36.25 Gy in five fractions. ILF were diagnosed using multiparametric MRI and/or biopsy prompted by rising PSA levels after achieving long-term nadir. Patient's characteristics were extracted from a prospective institutional quality of life trial (IRB 2009-510). Type of salvage therapy and post-salvage PSA were determined on subsequent follow-up and chart review. Results: Between December 2008 to August 2018, 998 men with low to intermediate risk prostate cancer were eligible for inclusion in this analysis. Twenty-four patients (low risk, n = 5; intermediate risk, n = 19) were found to have ILF within the prostate on either MRI (n = 19) and/or biopsy (n = 20). Median pre-treatment PSA was 7.55 ng/ml. Median time to diagnosis of ILF was 72 months (24-110 months) with median PSA at the time of ILF of 2.8 ng/ml (0.7-33 ng/ml). Median PSA doubling time was 17 months (5-47 months). Thirteen patients with biopsy proven ILF proceeded with salvage therapy (cryotherapy n = 12, HIFU n = 1). Of 12 patients who underwent cryotherapy, 7 had a post-treatment PSA of <0.1 ng/ml. One patient experienced a urethral-cutaneous fistula (grade 3 toxicity). Conclusion: The incidence of isolated local recurrence is rare in our cohort. Diagnosis and management of isolated local failures post-SBRT continues to evolve. Our report highlights the importance of early utilization of MRI and confirmatory biopsy at relatively low PSA levels and long PSA doubling time (1). Additionally, undetectable PSA levels after salvage therapy supports the role of early treatment in ILF (1). Further research is needed to determine appropriate patient selection and salvage modality in this population.

Favorable Biochemical Freedom From Recurrence With Stereotactic Body Radiation Therapy for Intermediate and High-Risk Prostate Cancer: A Single Institutional Experience With Long-Term Follow-Up

Purpose/Objective(s): The current study reports long-term overall survival (OS) and biochemical freedom from recurrence (BFFR) after stereotactic body radiation therapy (SBRT) for men with intermediate and high-risk prostate cancer in a single community hospital setting with early adoption. Materials/Methods: Ninety-seven consecutive men with intermediate and high-risk prostate cancer treated with SBRT between 2007 and 2015 were retrospectively studied. Categorical variables for analysis included National Comprehensive Cancer Network risk group, race, Gleason grade group, T stage, use of androgen deprivation therapy, and planning target volume dose. Continuous variables for analysis included pretreatment prostate-specific antigen (PSA), percent cores positive, age at diagnosis, PSA nadir, prostate volume, percent prostate that received 40 Gy, and minimum dose to 0.03 cc of prostate (Dmin). BFFR was assessed using the Phoenix nadir +2 definition. OS and BFFR were estimated using Kaplan-Meier (KM) methodology with comparisons accomplished using log-rank statistics. Multivariable analysis (MVA) was accomplished with a backwards selection Cox proportional-hazards model with statistical significance taken at the p < 0.05 level. Results: Median FU is 78.4 months. Five- and ten-year OS KM estimates are 90.9 and 73.2%, respectively, with 19 deaths recorded. MVA reveals pretreatment PSA (p = 0.032), percent prostate 40 Gy (p = 0.003), and race (p = 0.031) were predictive of OS. Five- and nine-year BFFR KM estimates are 92.1 and 87.5%, respectively, with 10 biochemical failures recorded. MVA revealed PSA nadir (p < 0.001) was the only factor predictive of BFFR. Specifically, for every one-unit increase in PSA nadir, there was a 4.2-fold increased odds of biochemical failure (HR = 4.248). No significant differences in BFFR were found between favorable intermediate, unfavorable intermediate, and high-risk prostate cancer (p = 0.054) with 7-year KM estimates of 96.6, 81.0, and 85.7%, respectively. Conclusions: Favorable OS and BFFR can be expected after SBRT for intermediate and high-risk prostate cancer with non-significant differences seen for BFFR between favorable intermediate, unfavorable intermediate, and high-risk groups. Our 5-year BFFR compares favorably with the HYPO-RT-PC trial of 84%. PSA nadir was predictive of biochemical failure. This study is ultimately limited by the small absolute number of high-risk patients included.

Dual Role of Bacteria in Carcinoma: Stimulation and Inhibition

Although what unifies the carcinogenic microorganisms has not been determined by multiple studies, the role of bacteria in the development of neoplasms has not been properly elucidated. In this review, we discuss links between the bacterial species and cancer, with focus on immune responses for the stimulation of tumor cells such as induction of inflammation. Finally, we will describe the potential therapeutic strategies of bacteria on target tumors to improve treatment while mitigating adverse reactions. Cancer is a series of genetic changes that transform normal cells into tumor cells. These changes come from several reasons, including smoking, drinking alcohol, sunlight, exposure to chemical or physical factors, and finally chronic infection with microorganisms, including bacteria. In fact, bacterial infections are not carcinogenic, but recently it was discovered that the association between bacteria and cancer is through two mechanisms, the first stimulating chronic inflammation and the second producing carcinogenic metabolites. While bacteria are carcinogenic agents also, they have a dual role eliminating and removing tumor cells. However, the traditional cancer treatments that include chemotherapy, radiotherapy, surgery, and immunotherapy increase the chances of survival, and there are many side effects of these therapies, including the high toxicity of tissues and normal cells, could not penetrate the tumor cells, and resistance of these therapies by tumor cells. Therefore, the world has turned to an alternative solution, which is the use of genetically engineered microorganisms; thus, the use of living bacteria targeting cancerous cells is the unique option to overcome these challenges. Bacterial therapies, whether used alone or combination with chemotherapy, give a positive effect to treat multiple conditions of cancer. Also, bacteria can be used as vectors for drug, gene, or therapy, and this is a great step to treat cancer. Thus, we review the mechanisms underlying the interaction of the microbiota residents with cancer. Cancer-associated bacteria differ from those in healthy human and are linked with gene-expression profile. We also discuss how live bacteria interact with tumor microenvironments to induce tumor regression through colonization and spread. Finally, we provide past and ongoing clinical trials that include bacteria targeting tumors.

A-blockers for the management of lower urinary tract symptoms in patients with prostate cancer treated with external beam radiotherapy: a randomized controlled study

BACKGROUND

This is a prospective study aiming to assess the efficacy of α-blockers in treating radiotherapy-induced symptoms of the lower urinary tract and its possible prophylactic role on acute urinary retention (AUR) in patients undergoing radical external beam radiotherapy (EBRT) for localized prostate cancer (PCa).

METHODS

Overall, 108 patients with localized PCa were recruited and randomly assigned in to two groups; 54 patients of Group 1 received tamsulosin 0.4 mg once daily with the initiation of EBRT and for 6 months and 54 patients of Group 2 served as the control group. All patients received radical EBRT and had post-void volume (Vres) assessment. The International Prostate Symptom Score (IPSS) questionnaire and evaluation of episodes of AUR were performed after the end of radiotherapy, at 3 and at 6 months.

RESULTS

The incidence of AUR was significantly (p = 0.027) lower in group 1 compared to group 2. No independent predictive factors for AUR were identified in regression analysis. The IPSS changes in univariate and multivariate analysis at 3 months showed significant correlation with α-blockers only, while at 6 months showed significant correlation with Vres assessments (at 3 and 6 months) and with α-blockers. Side effects due to medication were mild and none of the patients discontinued the treatment.

CONCLUSIONS

The selective use of α-blocker appears to prevent AUR in EBRT-treated patients. Although the administration of α-blockers might relieve patient-reported symptoms, there are no established independent predictive factors to distinguish patients who may benefit.

Prostatic irradiation-induced sexual dysfunction: A review and multidisciplinary guide to management in the radical radiotherapy era (Part II on Urological Management)

Prostate cancer is the most common malignancy in men and the second leading cause of cancer-related death in men. Radiotherapy is a curative option that is administered via external beam radiation, brachytherapy, or in combination. Sexual dysfunction is a common toxicity following radiotherapy, similar to men undergoing radical prostatectomy, but the etiology is different. The pathophysiology of radiation-induced sexual dysfunction is multi-factorial, and the toxicity is a major cause of impaired quality of life among long-term prostate cancer survivors. Management of a patient's sexual function during and after radiotherapy requires multidisciplinary coordination of care between radiation oncology, urology, psychiatry, pharmacy, and dermatology. This review provides a framework for clinicians to better understand prostatic radiotherapy-induced sexual dysfunction diagnosis, evaluation, and a patient-centered approach to toxicity preventive strategies and management.

Multi-Institutional Analysis of Synchronous Prostate and Rectosigmoid Cancers

Purpose: To perform a multi-institutional analysis of patients with synchronous prostate and rectosigmoid cancers.

Materials and Methods: A retrospective review of Duke University and Durham Veterans Affairs Medical Center records was performed for men with both prostate and rectosigmoid adenocarcinomas from 1988 to 2017. Synchronous presentation was defined as symptoms, diagnosis, or treatment of both cancers within 12 months of each other. The primary study endpoint was overall survival. Univariate and multivariable Cox regression was performed.

Results: Among 31,883 men with prostate cancer, 330 (1%) also had rectosigmoid cancer and 54 (16%) of these were synchronous. Prostate cancer was more commonly the initial diagnosis (59%). Fifteen (28%) underwent prostatectomy or radiotherapy before an established diagnosis of rectosigmoid cancer. Stage I, II–III, or IV rectosigmoid cancer was present in 26, 57, and 17% of men, respectively. At a median follow-up of 43 months, there were 18 deaths due rectosigmoid cancer and two deaths due to prostate cancer. Crude late grade ≥3 toxicities include nine (17%) gastrointestinal and six (11%) genitourinary. Two anastomotic leaks following low anterior resection occurred in men who received a neoadjuvant radiotherapy prostate dose of 70.6–76.4 Gy. Rectosigmoid cancer stages II–III (HR 4.3, p = 0.02) and IV (HR 16, p < 0.01) as well as stage IV prostate cancer (HR 31, p < 0.01) were associated with overall survival on multivariable analysis.

Conclusions: Synchronous rectosigmoid cancer is a greater contributor to mortality than prostate cancer. Men aged ≥45 with localized prostate cancer should undergo colorectal cancer screening prior to treatment to evaluate for synchronous rectosigmoid cancer.

Prostatic irradiation-induced sexual dysfunction: a review and multidisciplinary guide to management in the radical radiotherapy era (Part I defining the organ at risk for sexual toxicities)

Prostate cancer is the most common malignancy and the second leading cause of cancer-related death in men. Radiotherapy is a curative option that is administered via external beam radiation, brachytherapy, or in combination. Erectile, ejaculatory and orgasm dysfunction(s) is/are known potential and common toxicities associated with prostate radiotherapy. Our multidisciplinary team of physicians and/or scientists have written a three (3) part comprehensive review of the pathogenesis and management radiation-induced sexual dysfunction. Part I reviews pertinent anatomy associated with normal sexual function and then considers the pathogenesis of prostate radiation-induced sexual toxicities. Next, our team considers the associated radiobiological (including the effects of time, dose and fractionation) and physical (treatment planning and defining a novel Organ at Risk (OAR)) components that should be minded in the context of safe radiation treatment planning. The authors identify an OAR (i.e., the prostatic plexus) and provide suggestions on how to minimize injury to said OAR during the radiation treatment planning process.

Ten-Year Update of a Randomized, Prospective Trial of Conventional Fractionated Versus Moderate Hypofractionated Radiation Therapy for Localized Prostate Cancer

PURPOSE

The previously published single institution randomized prospective trial failed to show superiority in the 5-year biochemical and/or clinical disease failure (BCDF) rate with moderate hypofractionated intensity-modulated radiation therapy (H-IMRT) versus conventionally fractionated IMRT (C-IMRT). We now present 10-year disease outcomes using updated risk groups and definitions of biochemical failure.

METHODS

Men with protocol-defined intermediate- and high-risk prostate adenocarcinoma were randomly assigned to receive C-IMRT (76 Gy in 38 fractions) or H-IMRT (70.2 Gy in 26 fractions). Men with high-risk disease were all prescribed 24 months of androgen deprivation therapy (ADT) and had lymph node irradiation. Men with intermediate risk were prescribed 4 months of ADT at the discretion of the treating physician. The primary endpoint was cumulative incidence of BCDF. We compared disease outcomes and overall mortality by treatment arm, with sensitivity analyses for National Comprehensive Cancer Network (NCCN) risk group adjustment.

RESULTS

Overall, 303 assessable men were randomly assigned to C-IMRT or H-IMRT. The median follow-up was 122.9 months. Per updated NCCN risk classification, there were 28 patients (9.2%) with low-risk, 189 (62.4%) with intermediate-risk, and 86 (28.4%) with high-risk prostate cancer. The arms were equally balanced for clinicopathologic factors, except that there were more black patients in the C-IMRT arm (17.8% v 7.3%; P = .02). There was no difference in ADT use (P = .56). The 10-year cumulative incidence of BCDF was 25.9% in the C-IMRT arm and was 30.6% in the H-IMRT arm (hazard ratio, 1.31; 95% CI, 0.82 to 2.11). The two arms also had similar cumulative 10-year rates of biochemical failure, prostate cancer-specific mortality, and overall mortality; however, the 10-year cumulative incidence of distant metastases was higher in the H-IMRT arm (rate difference, 7.8%; 95% CI, 0.7% to 15.1%).

CONCLUSION

H-IMRT failed to demonstrate superiority compared with C-IMRT in long-term disease outcomes.

Protective Effect and Mechanism of Action of Rosmarinic Acid on Radiation-Induced Parotid Gland Injury in Rats

The parotid glands are damaged by oxidative stress and a series of pathophysiological changes after irradiation. Rosmarinic acid (RA) is a natural antioxidant that provides a radioprotective effect against harmful damage from ionizing radiation. The present study aims to explore the protective effects of RA on radiation-induced parotid gland injury and its underlying mechanism. Sprague-Dawley rats were irradiated with 15 Gy X-ray and treated with different concentrations of RA (30, 60, and 120 mg/kg) or amifostine (AMI, 250 mg/kg). Saliva secretion function, oxidative stress, apoptosis, the inflammatory response, and fibrosis were determined by the measurement of the salivary flow rate, enzyme-linked immunosorbent assay, transferase-mediated DUTP Nick end labeling, Western blot, quantitative real time polymerase chain reaction, and hematoxylin and eosin staining. Here, we show that RA treatment significantly attenuated reactive oxygen species by a direct hindrance effect and the indirect activation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha/nicotinamide adenine dinucleotide phosphate oxidase 4 signaling. Rosmarinic acid not only reduced apoptosis by inhibiting p53/jun N-terminal kinase activation but also reduced parotid gland tissue fibrosis by downregulating inflammatory factor levels. Compared to AMI, RA has the obvious advantages of late efficacy and convenient usage. Moreover, 60 mg/kg is the minimum effective dose of RA. Therefore, RA can potentially be applied as a therapeutic radioprotective agent to treat radiation-induced parotid gland injury in the future.

[Indications and outlooks of radiohormonal therapy of high-risk prostate cancers]

Prostate cancer is a sensitive adenocarcinoma, in more than 80% of cases, to chemical castration, due to its hormone dependence. Locally advanced and/or high-risk cancer is defined based on clinical stage, initial prostate specific antigen serum concentration value or high Gleason score. Hormone therapy associated with radiation therapy is the standard of management and improves local control, reduces the risk of distant metastasis and improves specific and overall survival. Duration of hormone therapy, dose level of radiation therapy alone or associated with brachytherapy are controversial data in the literature. The therapeutic choice, multidisciplinary, depends on the age and comorbidity of the patient, the prognostic criteria of the pathology and the urinary function of the patient. Current research focuses on optimizing local and distant control of these aggressive forms and incorporates neoadjuvant or adjuvant chemotherapy and also new hormone therapies.

Ultra-hypofractionated radiation therapy for unfavourable intermediate-risk and high-risk prostate cancer is safe and effective: 5-year outcomes of a phase II trial

OBJECTIVES

To report toxicity (primary endpoint) and biochemical disease-free survival (BDFS) outcomes of a phase II trial evaluating ultra-hypofractionated radiation therapy (UHRT), focusing on patients with unfavourable intermediate-risk and high-risk prostate cancer (PCa).

PATIENTS AND METHODS

From 2012 to 2017, 154 patients (92 with unfavourable intermediate-risk or high-risk PCa) were treated with helical TomoTherapy delivering 43.8-45.2 Gy in eight fractions over 3 weeks. Of these, 73% received hormonotherapy (51% neoadjuvant).

RESULTS

The median (range) follow-up was 48 (19-84) months. For the whole series, crude BDFS and 5-year BDFS rates were 97.4% and 94.3%, respectively. The corresponding figures for unfavourable intermediate-risk and high-risk PCa were 96.7% and 90%, respectively. The crude metastasis-free survival rate was 98% for the unfavourable intermediate-risk and high-risk group. For the whole series, the 5-year cumulative urinary/intestinal grade 2+ late toxicity was 17.8/7.4%. No grade 4-5 toxicity was observed. One patient experienced late grade 3 toxicity (urinary).

CONCLUSION

This eight-fraction UHRT regimen can be safely delivered to patients with unfavourable intermediate-risk/high-risk PCa. Its relapse rates are similar to those reported for the combination of external beam radiotherapy plus brachytherapy, however, the observed toxicity profile is milder. The disease survival rates compare favourably with historical controls in some other forms of radiotherapy, with similar side effects. Since the low rate of biochemical/metastasis relapse is encouraging, further research to confirm these results is justified.

MRI-Guided Ultrafocal Salvage High-Dose-Rate Brachytherapy for Localized Radiorecurrent Prostate Cancer: Updated Results of 50 Patients

PURPOSE

Most patients with local prostate cancer recurrence after radiation therapy undergo palliative androgen deprivation therapy because whole-gland salvage treatments have a high risk of severe toxicity. Focal treatment reduces this risk while offering a second opportunity for cure. We report updated outcomes of ultrafocal salvage high-dose-rate brachytherapy (HDR-BT).

METHODS AND MATERIALS

Prospectively collected data from the first 50 treated patients were analyzed. Disease status was assessed by 3T multiparametric magnetic resonance imaging (MRI), 18F-Choline or 68Ga-prostate-specific membrane antigen positron emission tomography/computed tomography, and systematic or tumor-targeted biopsies. Ultrafocal salvage HDR-BT (1 × 19 Gy) was performed by implanting the clinical target volume (CTV: gross tumor volume + 5 mm margin) under fused transrectal ultrasound/MRI guidance. Follow-up included toxicity grading (using Common Terminology Criteria for Adverse Events 4.0), quality of life assessment, and prostate-specific antigen (PSA) testing.

RESULTS

Median follow-up was 31 months. Median CTV D95% was 18.8 Gy. We observed 2% grade 3 genitourinary toxicity, no grade 3 gastrointestinal toxicity, and 22% newly developed grade 3 erectile dysfunction. Five of 13 patients (38%) with self-reported pretreatment potency (International Index of Erectile Function >17) remained potent. Clinically relevant quality of life deterioration was reported for only 6 of 31 items and was not statistically significant. Biochemical failure (nadir + 2) occurred in 26 patients. Among intraprostatic recurrences, 73% were in field. After 2.5 years, biochemical disease-free survival was 51% (95% confidence interval, 37%-69%), metastases-free survival was 75% (64%-89%), androgen deprivation therapy-free survival was 90% (82%-99%), and overall survival was 98% (94%-100%). Presalvage PSA, CTV size, and stage ≥T3 were significantly associated with biochemical failure. Higher-risk patients (stage ≥T3, PSA ≥10, or PSA double time ≤9 months) had 25% biochemical disease-free survival at 2.5 years versus 71% for lower-risk patients.

CONCLUSIONS

At this early stage, MRI-guided ultrafocal HDR-BT seems to be a safe salvage treatment option, with acceptable biochemical control in a well-selected group of patients and potential for effectively postponing androgen deprivation therapy.

Longitudinal model-based meta-analysis for survival probabilities in patients with castration-resistant prostate cancer

PURPOSE

The aims of this longitudinal model-based meta-analysis (MBMA) were to indirectly compare the time courses of survival probabilities and to identify corresponding potential significant covariates across approved drugs in patients with castration-resistant prostate cancer (CRPC).

METHODS

A systematic literature review for monotherapy studies in patients with CRPC was conducted up to August 8, 2018. The time courses of progression-free survival (PFS) and overall survival (OS) were fitted with parametric survival models. Covariate analyses were performed to determine the impact of treatment drugs, dosing regimens, and patient characteristics on the survival probabilities. Simulations were carried out to quantify the magnitude of covariate effects.

RESULTS

A total of 146 studies including clinical trials and real-world data on longitudinal survival probabilities in 20,712 patients with CRPC were included in our meta-database. The time courses of PFS and OS probabilities were best described by the log-logistic model. There was no significant difference in median OS and PFS between docetaxel, cabazitaxel, abiraterone acetate, and enzalutamide. There was no significant dose-response relationship in PFS or OS for docetaxel at 50 to 120 mg/m² every 3 weeks (Q3W) and cabazitaxel at 20 to 25 mg/m² Q3W. Model-based simulations indicated that PFS probability was associated with chemotherapy, Gleason score, and baseline prostate-specific antigen (BLPSA), while OS probability was associated with chemotherapy, Gleason score, visceral metastasis, Eastern Cooperative Oncology Group performance status, and BLPSA.

CONCLUSION

Our modeling and simulation framework can be applied to support indirect comparison, dose selection, and go/no-go decision-making for new agents targeting CRPC.