Quantifying Intrafraction Motion and the Impact of Gating for Magnetic Resonance Imaging-Guided Stereotactic Radiation therapy for Prostate Cancer: Analysis of the Magnetic Resonance Imaging Arm From the MIRAGE Phase 3 Randomized Trial

PURPOSE

Real-time intrafraction tracking/gating is an integral component of magnetic resonance imaging-guided radiation therapy (MRgRT) and may have contributed to the acute toxicity reduction during prostate stereotactic body radiation therapy observed on the MRgRT-arm of the MIRAGE (MAGNETIC RESONANCE IMAGING-GUIDED Stereotactic Body Radiotherapy for Prostate Cancer) randomized trial (NCT04384770). Herein we characterized intrafraction prostate motion and assessed gating effectiveness.

METHODS AND MATERIALS

Seventy-nine patients were treated on an MR-LINAC. Real-time cine imaging was acquired at 4Hz in a sagittal plane. If >10% of the prostate area moved outside of a 3-mm gating boundary, an automatic beam hold was initiated. An in-house tool was developed to retrospectively extract gating signal for all patients and identify the tracked prostate in each cine frame for a subgroup of 40 patients. The fraction of time the prostate was within the gating window was defined as the gating duty cycle (GDC).

RESULTS

A total of 391 treatments from 79 patients were analyzed. Median GDC was 0.974 (IQR, 0.916-0.983). Fifty (63.2%) and 24 (30.4%) patients had at least 1 fraction with GDC ≤0.9 and GDC ≤0.8, respectively. Incidence of low GDC fractions among patients appeared stochastic. Patients with minimum GDC <0.8 trended toward more frequent grade 2 genitourinary toxicity compared with those with minimum GDC >0.8 (38% vs 18%, P = .065). Prostate intrafraction motion was mostly along the bladder-rectum axis and predominantly in the superior-anterior direction. Motion in the inferior-posterior direction was associated with significantly higher rate of acute grade 2 genitourinary toxicity (66.7% vs 13.9%, P = .001). Gating limited mean prostate motion during treatment delivery in fractions with a GDC <0.9 (<0.8) to 2.9 mm (2.9 mm) versus 4.1 mm (4.7 mm) for ungated motion.

CONCLUSIONS

Fractions with large intrafraction motion were associated with increased toxicity and their occurrence among patients appears stochastic. Real-time tracking/gating effectively mitigated this motion and is likely a major contributing factor of acute toxicity reduction associated with MRgRT.

Intra-fractional geometric and dose/volume metric variations of magnetic resonance imaging-guided stereotactic radiotherapy of prostate bed after radical prostatectomy

Background and purpose

Magnetic Resonance Imaging (MRI)-guided Stereotactic body radiotherapy (SBRT) treatment to prostate bed after radical prostatectomy has garnered growing interests. The aim of this study is to evaluate intra-fractional anatomic and dose/volume metric variations for patients receiving this treatment.

Materials and methods

Nineteen patients who received 30-34 Gy in 5 fractions on a 0.35T MR-Linac were included. Pre- and post-treatment MRIs were acquired for each fraction (total of 75 fractions). The Clinical Target Volume (CTV), bladder, rectum, and rectal wall were contoured on all images. Volumetric changes, Hausdorff distance, Mean Distance to Agreement (MDA), and Dice similarity coefficient (DSC) for each structure were calculated. Median value and Interquartile range (IQR) were recorded. Changes in target coverage and Organ at Risk (OAR) constraints were compared and evaluated using Wilcoxon rank sum tests at a significant level of 0.05.

Results

Bladder had the largest volumetric changes, with a median volume increase of 48.9 % (IQR 28.9-76.8 %) and a median MDA of 5.1 mm (IQR 3.4-7.1 mm). Intra-fractional CTV volume remained stable with a median volume change of 1.2 % (0.0-4.8 %). DSC was 0.97 (IQR 0.94-0.99). For the dose/volume metrics, there were no statistically significant changes observed except for an increase in bladder hotspot and a decrease of bladder V32.5 Gy and mean dose. The CTV V95% changed from 99.9 % (IQR 98.8-100 %) to 99.6 % (IQR 93.9-100 %).

Conclusion

Despite intra-fractional variations of OARs, CTV coverage remained stable during MRI-guided SBRT treatments for the prostate bed.

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.

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

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

Dosimetric predictors for genitourinary toxicity in MR-guided stereotactic body radiation therapy (SBRT): Substructure with fraction-wise analysis

BACKGROUND

MR-guided radiation therapy (MRgRT) systems provide superior soft tissue contrast than x-ray based systems and can acquire real-time cine for treatment gating. These features allow treatment planning margins to be reduced, allowing for improved critical structure sparing and reduced treatment toxicity. Despite this improvement, genitourinary (GU) toxicity continues to affect many patients.

PURPOSE

(1) To identify dosimetric predictors, potentially in combination with clinical parameters, of GU toxicity following SBRT by leveraging MRgRT to accurately monitor daily dose, beyond predicted dose calculated during planning. (2) Improve awareness of toxicity-sensitive bladder substructures, specifically the trigone and urethra.

METHODS

Sixty-nine prostate cancer patients (NCT04384770 clinical trial) were treated on a ViewRay MRIdian MRgRT system, with 40 Gy prescribed to 95% of the PTV in over five fractions. Overall, 17 (24.6%) prostate patients reported acute grade 2 GU toxicity. The CTV, PTV, bladder, bladder wall, trigone, urethra, rectum, and rectal wall were contoured on the planning and daily treatment MRIs. Planning and daily treatment DVHs (0.1 Gy increments), organ doses (min, max, mean), and organ volumes were recorded. Daily dose was estimated by transferring the planning dose distributions to the daily MRI based on the daily setup alignment. Patients were partitioned into a training (55) and testing set (14). Dose features were pre-filtered using a t-test followed by maximum relevance minimum redundancy (MRMR) algorithm. Logistic regression was investigated with regularization to select dosimetric predictors. Specifically, two approaches: time-group least absolute shrinkage and selection (LASSO), and interactive grouped greedy algorithm (IGA) were investigated. Shared features across the planning and five treatment fractions were grouped to encourage consistency and stability. The conventional flat non-temporally grouped LASSO was also evaluated to provide a solid benchmark. After feature selection, a final logistic regression model was trained. Dosimetric regression models were compared to a clinical regression model with only clinical parameters (age, baseline IPSS, prostate gland size, ADT usage, etc.) and a hybrid model, combining the best performing dosimetric features with the clinical parameters, was evaluated. Final model performance was evaluated on the testing set using accuracy, sensitivity, and specificity determined by the optimal threshold of the training set.

RESULTS

IGA had the best testing performance with an accuracy/sensitivity/specificity of 0.79/0.67/0.82, selecting 12 groups covering the bladder (V19.8 Gy, V20.5 Gy), bladder wall (19.7 Gy), trigone (15.9, 18.2, 43.3 Gy), urethra (V41.4 Gy, V41.7 Gy), CTV (V41.9 Gy), rectum (V8.5 Gy), and rectal wall (1.2, 44.1 Gy) dose features. Absolute bladder V19.8 Gy and V20.5 Gy were the most important features, followed by relative trigone 15.9  and 18.2 Gy. Inclusion of clinical parameters in the hybrid model with IGA did not significantly change regression performance.

CONCLUSION

Overall, IGA feature selection resulted in the best GU toxicity prediction performance. This exploratory study demonstrated the feasibility of identification and analysis of dosimetric toxicity predictors with awareness to sensitive substructures and daily dose to potentially provide consistent and stable dosimetric metrics to guide treatment planning. Further patient accruement is warranted to further assess dosimetric predictor and perform validation.

Racial and Ethnic Disparities in Use of Novel Hormonal Therapy Agents in Patients With Prostate Cancer

Importance

Novel hormonal therapy (NHT) agents have been shown to prolong overall survival in numerous randomized clinical trials for patients with advanced prostate cancer (PCa). There is a paucity of data regarding the pattern of use of these agents in patients from different racial and ethnic groups.

Objective

To assess racial and ethnic disparities in the use of NHT in patients with advanced PCa.

Design, Setting, and Participants

This cohort study comprised all men diagnosed with de novo advanced PCa (distant metastatic [M1], regional [N1M0], and high-risk localized [N0M0] per Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy [STAMPEDE] trial criteria) with Medicare Part A, B, and D coverage between January 1, 2011, and December 31, 2017, in a Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database including prescription drug records. Data analysis took place from January through May 2023.

Exposures

Race and ethnicity (Black [non-Hispanic], Hispanic, White, or other [Alaska Native, American Indian, Asian, Pacific Islander, or not otherwise specified and unknown]) abstracted from the SEER data fields.

Main Outcomes and Measures

The primary outcome was receipt of an NHT agent (abiraterone, enzalutamide, apalutamide, or darolutamide) using a time-to-event approach.

Results

The study included 3748 men (median age, 75 years [IQR, 70-81 years]). A total of 312 (8%) were Black; 263 (7%), Hispanic; 2923 (78%), White; and 250 (7%) other race and ethnicity. The majority of patients had M1 disease (2135 [57%]) followed by high-risk N0M0 (1095 [29%]) and N1M0 (518 [14%]) disease. Overall, 1358 patients (36%) received at least 1 administration of NHT. White patients had the highest 2-year NHT utilization rate (27%; 95% CI, 25%-28%) followed by Hispanic patients (25%; 95% CI, 20%-31%) and patients with other race or ethnicity (23%; 95% CI, 18%-29%), with Black patients having the lowest rate (20%; 95% CI, 16%-25%). Black patients had significantly lower use of NHT compared with White patients, which persisted at 5 years (37% [95% CI, 31%-43%] vs 44% [95% CI, 42%-46%]; P = .02) and beyond. However, there was no significant difference between White patients and Hispanic patients or patients with other race or ethnicity in NHT utilization (eg, 5 years: Hispanic patients, 38% [95% CI, 32%-46%]; patients with other race and ethnicity: 41% [95% CI, 35%-49%]). Trends of lower utilization among Black patients persisted in the patients with M1 disease (eg, vs White patients at 5 years: 51% [95% CI, 44%-59%] vs 55% [95% CI, 53%-58%]). After adjusting for patient, disease, and sociodemographic factors in multivariable analysis, Black patients continued to have a significantly lower likelihood of NHT initiation (adjusted subdistribution hazard ratio, 0.76; 95% CI, 0.61-0.94, P = .01).

Conclusions and Relevance

In this cohort study of Medicare beneficiaries with advanced PCa, receipt of NHT agents was not uniform by race, with decreased use observed in Black patients compared with the other racial and ethnic groups, likely due to multifactorial obstacles. Future studies are needed to identify strategies to address the disparities in the use of these survival-prolonging therapies in Black patients.

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

PURPOSE

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

METHODS AND MATERIALS

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

RESULTS

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

CONCLUSIONS

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

Developing an Online Interactive Volumetric Surface Viewer for Visualizing Spatial Distribution of Intracranial Lesions

PURPOSE/OBJECTIVE(S)

The exact location of intracranial neoplasms and metastatic lesions within the cortex may provide key insights into predicting treatment effectiveness and toxicities. Modern neuroimaging approaches have enabled precise, rapid diffeomorphic alignment from individual brains to an atlas, allowing the registration of contours and dose distributions onto a common template. However, there is a paucity of intuitive tools to perform such functions. Here, we developed an online interactive volumetric surface viewer that displays distribution of brain lesions of specific clinical features within the context of prior radiation treatment in populations of patients on a common atlas.

MATERIALS/METHODS

Data from 647 patients treated at our institution with radiotherapy for intracranial lesions were analyzed with FreeSurfer to perform intensity normalization, skull-stripping, and affine registration to Talairach coordinates. A custom-built VoxelMorph model was trained to register T1 MRIs to a common atlas. Radiation dose maps and contours on underlying CT simulation scans were rigidly aligned to the T1 MRIs. The diffeomorphic warps were then applied to the radiation dose maps and contours, including the gross tumor volumes. Surface rendering of the template atlas was performed using FreeSurfer and visualized using PyCortex. Clinical information including primary sites for brain metastases, lesion size, survival, recurrence, use of anti-epileptic medications, radiation necrosis, and neuro-cognitive toxicity was embedded into the PyCortex viewer.

RESULTS

The custom-trained VoxelMorph model enabled rapid normalization of the T1MRIs to the atlas brain. PyCortex allows for interactive visualization of the spatial distribution of lesions on the cortical surface across a rich array of clinical parameters. Initial maps have qualitatively revealed a predilection for metastases in the right hemisphere. This WebGL viewer allows intuitive clinical interrogation on a visual surface enabling population inferences. For example, one can visualize the distribution of brain metastases of a large patient cohort based on their primary tumor sites, propensity for seizure and risk for radionecrosis.

CONCLUSION

We successfully built an online interactive viewer to visualize the spatial distribution of intracranial lesions on a common reference. Our approach extends prior work allowing visual interaction of lesions and real-time generation of inference maps by combining a front-end viewer and back-end database of clinical data. This viewer may represent a critical step towards uncovering the location-dependent breakdown of the blood-brain-barrier, differentiating the propensity of primary lesions metastasizing to brain regions, and allowing the discovery of associations of previously understudied spatial neighborhoods. We plan to release a publicly available web-based viewer to further explore, interrogate, and inform future radiation treatments.

Treatment Delivery Gating of MRI-Guided Stereotactic Radiotherapy for Prostate Cancer: An Exploratory Analysis of a Phase III Randomized Trial of CT-Vs. MR-Guided Radiotherapy (MIRAGE)

PURPOSE/OBJECTIVE(S)

Compared to CT-guided radiotherapy, MRI-guided radiotherapy (MRgRT) has been shown to reduce acute physician-scored and patient-reported gastrointestinal and genitourinary (GU) toxicities associated with prostate stereotactic body radiotherapy (SBRT) in the MIRAGE randomized trial (NCT04384770). We hypothesize that real-time intrafraction tracking/gating is important and is a critical enabler of aggressive margin reduction with MRgRT.

MATERIALS/METHODS

79 patients received MRgRT on the MIRAGE trial with a planning margin of 2mm around the prostate and proximal seminal vesicles, which were treated to 40 Gy in five fractions on an MR-Linac. Tracking was performed at 4 frames/second in the sagittal plane during treatment with a gating boundary of 3mm for automatic beam hold. An in-house tool was developed to extract treatment time and beam gating status based on treatment logs and real-time cine images. The ratio of the time that the target was within the gating window/total time of target inside or outside the gating boundary was defined as the duty cycle (DC). Target contours were extracted from each frame of tracking and overlaid to create a motion-convolved target occupancy map. Minimum isotropic expansions of the prostate to cover 85%, 90% and 95% of the intrafraction motion were calculated with and without gating.

RESULTS

Median treatment time per fraction including image guidance procedure and beam delivery was 24.3 min (IQR: 22.2-27.7 min). The median time for image guidance 5.4 min (IQR: 4.2-6.7 min). A total of 391 treatment fractions were analyzed and the median DC per fraction was 0.974 (IQR: 0.926 -0.983). 89 (22.8%) and 35 (9.0%) of fractions had DC<90% and <80%, respectively, corresponding to 50/79 (62.3%) and 24/79 (30.4%) of patients having at least one fraction with a DC<90% and <80%, respectively. The minimum duty cycle of all fractions was lower among patients with grade ≥2 GU toxicity compared to those with grade 0-1 GU toxicity (mean 79.8% vs. 85.9%, p = 0.06). The proportion of patients with grade ≥2 GU toxicity was also greater in patients with a minimum gating cycle <80% (37.5% vs. 18.2%, p = 0.06). Gating significantly decreased the minimum isotropic expansion of the prostate to cover 85%, 90% and 95% of the intrafraction motion (p<0.0001 for all). Prostate intrafraction motion tended to be along the bladder-rectum axis secondary to bladder filling, rectal gas and bulk motion. Fractions with large prostate motion were mostly stochastic.

CONCLUSION

A large fraction (30%) of patients had at least of one treatment fraction with DC<80%, which correlated with increased acute GU toxicity. Gating effectively reduces the expansion needed to cover prostate intrafraction motion, and is necessary for real-time motion management given the unpredictable nature of prostate motion.

Patient-Reported Urinary and Bowel Quality of Life Outcomes Following External Beam Radiotherapy with or without High-Dose-Rate Brachytherapy Boost: Post-Hoc Analyses of TROG 03.04 (RADAR)

PURPOSE/OBJECTIVE(S)

One of the concerns with combining external beam radiotherapy (EBRT) with a high dose rate brachytherapy boost (HDRBT) for prostate cancer is increased toxicity. We aimed to evaluate long-term urinary and bowel quality of life (QoL) outcomes following EBRT vs EBRT + HDRBT using data from the TROG 03.04 trial.

MATERIALS/METHODS

Men who had dose-escalated EBRT (74 Gy) or EBRT (46 Gy) + HDRBT (19.5 Gy in 3 fractions) were included in this exploratory analysis. QoL outcomes were prospectively collected using the EORTC-QLQ-PR25 at baseline, end of radiotherapy, 12, 18, 24, 36, 60 months, and annually up to 10 years. QoL score was normalized to 0-100 with higher scores representing worse symptom burden. Minimal clinically important differences (MCIDs) were defined as differences in the respective QoL scores ≥0.5 standard deviations of the baseline QoL score. Mixed models for repeated measures were used to evaluate longitudinal changes in the QoL score between EBRT and EBRT + HDRBT arms. Logistic regression was used to evaluate differences in proportion of men with 2xMCID between EBRT and EBRT + HDRBT arms at each time point. Age, baseline QoL score, ECOG performance status, and duration of androgen deprivation therapy use (6 vs. 18 months) were adjusted for in all analyses.

RESULTS

Four hundred ninety-seven men were included in this study: 260 (52%) had EBRT and 237 (48%) had EBRT + HDRBT. The median baseline urinary QoL scores were 12.5 (IQR 4.2-19.0) and 8.3 (IQR 4.2-20.8) for men in EBRT and EBRT + HDRBT arms respectively (P = 0.5). Within the first 24 months, men in the EBRT + HDRBT arm had a slower rate of urinary QoL score resolution compared to men in the EBRT arm (P<0.001). At 12, 18, 24, and 36 months, men who had EBRT + HDRBT were 2.4 times (95% CI = 1.4-4.0; P<0.001), 3.1 times (95% CI = 1.8-5.1; P<0.001), 2.8 times (95% CI = 1.7-4.7; P<0.001), and 2.5 times (95% CI = 1.4-4.5; P = 0.002) more likely to have 2xMCID in urinary QoL scores compared to men who had EBRT alone. Beyond 24 months, there were no significant differences in the rate of urinary QoL score resolution between arms, and beyond 36 months there were no significant differences in the proportion with 2xMCID between arms. The median baseline bowel QoL score was 0 in both arms. There were no differences in the rate of bowel QoL score recovery over time between arms. Men who had EBRT + HDRBT were less likely to have 2xMCID in bowel QoL score in the immediate post-radiotherapy period (OR = 0.66; 95% CI = 0.45-0.97; P = 0.03) and at 60 months (OR = 0.51; 95% CI = 0.33-0.80; P = 0.003) compared to men who had EBRT.

CONCLUSION

EBRT + HDRBT is associated with disturbances in urinary QoL that are of greater magnitude compared to EBRT alone within the first 36 months of treatment, but the differences resolved after 36 months. EBRT + HDRBT is associated with less disturbances in bowel QoL immediately after treatment and at 60 months compared to EBRT alone.

Race-dependent association of clinical trial participation with improved outcomes for high-risk prostate cancer patients treated in the modern era

It is unclear whether cancer patients enrolled in clinical trials have improved outcomes compared with non-study patients. We compared prostate cancer-specific mortality (PCSM) in patients in a real-world setting (SEER-Medicare database) versus on a trial (NRG/RTOG 0521). The 7-year freedom from PCSM was superior in trial patients (92.4% vs. 88.1%, sHR = 1.77 [95% CI 1.05-2.97], P = 0.03). Black trial patients had significantly superior freedom from PCSM than Black real-world patients (sHR 6.52, 95% CI 1.43-29.72, P = 0.02), which was not seen among non-Black patients. Trial patients may have improved outcomes, and racial disparities are accentuated in the real world.

Selecting the optimal radiation modality in prostate cancer

There are numerous radiation modalities for the definitive treatment of localized prostate cancer. Classic clinical trials have established the basic tenets of treatment approaches, and emerging data have generated new potential avenues of treatment that optimize the therapeutic ratio by increasing prostate cancer tumor control while minimizing treatment-related toxicity. In the definitive setting, the selection of the optimal radiation therapy approach depends largely on the appropriate up-front risk stratification of men with prostate cancer, with greater intensification of treatment and greater integration of multimodality therapies for men with higher-risk disease. Hormonal therapy should be selectively deployed based on prognostic information derived from the National Comprehensive Cancer Network risk group and biologic tumor aggressiveness informed by genomic classifiers. Moreover, treatment intensification and target volume delineation are increasingly informed by molecular imaging and multiparametric magnetic resonance imaging. Herein, we perform a critical appraisal of the literature focusing on the optimal selection of radiation therapy modality for localized prostate cancer. Collaboration among medical oncologists, surgeons, and radiation oncologists will be critical for coordinating evidence-based radiation therapies when clearly indicated and for supporting shared decision-making when the evidence is incomplete.

Application of a genetic signature of late GU toxicity in SCIMITAR, a Post-op SBRT trial

Predictors of genitourinary toxicity after post-prostatectomy radiotherapy remain elusive. A previously defined germline DNA signature (PROSTOX) has shown predictive ability for late grade ≥ 2 GU toxicity after intact prostate stereotactic body radiotherapy. We explore whether PROSTOX would predict toxicity among patients receiving post-prostatectomy SBRT on a phase II clinical trial.

External Beam Radiation Therapy With or Without Brachytherapy Boost in Men With Very-High-Risk Prostate Cancer: A Large Multicenter International Consortium Analysis

PURPOSE

Very-high-risk (VHR) prostate cancer (PC) is an aggressive subgroup with high risk of distant disease progression. Systemic treatment intensification with abiraterone or docetaxel reduces PC-specific mortality (PCSM) and distant metastasis (DM) in men receiving external beam radiation therapy (EBRT) with androgen deprivation therapy (ADT). Whether prostate-directed treatment intensification with the addition of brachytherapy (BT) boost to EBRT with ADT improves outcomes in this group is unclear.

METHODS AND MATERIALS

This cohort study from 16 centers across 4 countries included men with VHR PC treated with either dose-escalated EBRT with ≥24 months of ADT or EBRT + BT boost with ≥12 months of ADT. VHR was defined by National Comprehensive Cancer Network (NCCN) criteria (clinical T3b-4, primary Gleason pattern 5, or ≥2 NCCN high-risk features), and results were corroborated in a subgroup of men who met Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy (STAMPEDE) trials inclusion criteria (≥2 of the following: clinical T3-4, Gleason 8-10, or PSA ≥40 ng/mL). PCSM and DM between EBRT and EBRT + BT were compared using inverse probability of treatment weight-adjusted Fine-Gray competing risk regression.

RESULTS

Among the entire cohort, 270 underwent EBRT and 101 EBRT + BT. After a median follow-up of 7.8 years, 6.7% and 5.9% of men died of PC and 16.3% and 9.9% had DM after EBRT and EBRT + BT, respectively. There was no significant difference in PCSM (sHR, 1.47 [95% CI, 0.57-3.75]; P = .42) or DM (sHR, 0.72, [95% CI, 0.30-1.71]; P = .45) between EBRT + BT and EBRT. Results were similar within the STAMPEDE-defined VHR subgroup (PCSM: sHR, 1.67 [95% CI, 0.48-5.81]; P = .42; DM: sHR, 0.56 [95% CI, 0.15-2.04]; P = .38).

CONCLUSIONS

In this VHR PC cohort, no difference in clinically meaningful outcomes was observed between EBRT alone with ≥24 months of ADT compared with EBRT + BT with ≥12 months of ADT. Comparative analyses in men treated with intensified systemic therapy are warranted.

Magnetic Resonance Imaging-Guided vs Computed Tomography-Guided Stereotactic Body Radiotherapy for Prostate Cancer: The MIRAGE Randomized Clinical Trial

Importance

Magnetic resonance imaging (MRI) guidance offers multiple theoretical advantages in the context of stereotactic body radiotherapy (SBRT) for prostate cancer. However, to our knowledge, these advantages have yet to be demonstrated in a randomized clinical trial.

Objective

To determine whether aggressive margin reduction with MRI guidance significantly reduces acute grade 2 or greater genitourinary (GU) toxic effects after prostate SBRT compared with computed tomography (CT) guidance.

Design, Setting, and Participants

This phase 3 randomized clinical trial (MRI-Guided Stereotactic Body Radiotherapy for Prostate Cancer [MIRAGE]) enrolled men aged 18 years or older who were receiving SBRT for clinically localized prostate adenocarcinoma at a single center between May 5, 2020, and October 1, 2021. Data were analyzed from January 15, 2021, through May 15, 2022. All patients had 3 months or more of follow-up.

Interventions

Patients were randomized 1:1 to SBRT with CT guidance (control arm) or MRI guidance. Planning margins of 4 mm (CT arm) and 2 mm (MRI arm) were used to deliver 40 Gy in 5 fractions.

Main Outcomes and Measures

The primary end point was the incidence of acute (≤90 days after SBRT) grade 2 or greater GU toxic effects (using Common Terminology Criteria for Adverse Events, version 4.03 [CTCAE v4.03]). Secondary outcomes included CTCAE v4.03-based gastrointestinal toxic effects and International Prostate Symptom Score (IPSS)-based and Expanded Prostate Cancer Index Composite-26 (EPIC-26)-based outcomes.

Results

Between May 2020 and October 2021, 156 patients were randomized: 77 to CT (median age, 71 years [IQR, 67-77 years]) and 79 to MRI (median age, 71 years [IQR, 68-75 years]). A prespecified interim futility analysis conducted after 100 patients reached 90 or more days after SBRT was performed October 1, 2021, with the sample size reestimated to 154 patients. Thus, the trial was closed to accrual early. The incidence of acute grade 2 or greater GU toxic effects was significantly lower with MRI vs CT guidance (24.4% [95% CI, 15.4%-35.4%] vs 43.4% [95% CI, 32.1%-55.3%]; P = .01), as was the incidence of acute grade 2 or greater gastrointestinal toxic effects (0.0% [95% CI, 0.0%-4.6%] vs 10.5% [95% CI, 4.7%-19.7%]; P = .003). Magnetic resonance imaging guidance was associated with a significantly smaller percentage of patients with a 15-point or greater increase in IPSS at 1 month (6.8% [5 of 72] vs 19.4% [14 of 74]; P = .01) and a significantly reduced percentage of patients with a clinically significant (≥12-point) decrease in EPIC-26 bowel scores (25.0% [17 of 68] vs 50.0% [34 of 68]; P = .001) at 1 month.

Conclusions and Relevance

In this randomized clinical trial, compared with CT-guidance, MRI-guided SBRT significantly reduced both moderate acute physician-scored toxic effects and decrements in patient-reported quality of life. Longer-term follow-up will confirm whether these notable benefits persist.

Trial Registration

ClinicalTrials.gov Identifier: NCT04384770.

LUNAR: a randomized Phase 2 study of 177 Lutetium-PSMA Neoadjuvant to Ablative Radiotherapy for Oligorecurrent Prostate Cancer (clinical trial protocol)

OBJECTIVE

To assess the efficacy of ¹⁷⁷ Lu-PNT2002, a novel radiolabelled small molecule that binds with high affinity to prostate-specific membrane antigen (PSMA), in combination with stereotactic body radiotherapy (SBRT) to all sites of metastasis, vs SBRT alone, in men with oligorecurrent metastatic hormone-sensitive prostate cancer (mHSPC).

PATIENTS AND METHODS

The ¹⁷⁷ Lutetium-PSMA Neoadjuvant to Ablative Radiotherapy for Oligorecurrent Prostate Cancer (LUNAR) trial is an open-label, randomized, stratified, two-arm, single-centre, Phase 2 trial to compare the efficacy and safety of neoadjuvant ¹⁷⁷ Lu-PNT2002 plus SBRT vs SBRT alone in men with oligorecurrent mHSPC. Key eligibility criteria include one to five lesions identified on a PSMA positron emission tomography (PET)/computed tomography (CT) scan centrally reviewed by a board-certified nuclear medicine physician. Key exclusion criteria include castrate-resistant disease, de novo oligometastatic disease and receipt of androgen deprivation therapy (ADT) within 6 months of trial enrolment. The trial aims to enrol 100 patients who will be centrally randomized to one of the two treatment arms, in a 1:1 ratio. Patients in the control arm receive SBRT to all sites of disease. Patients in the experimental arm receive two cycles of neoadjuvant ¹⁷⁷ Lu-PNT2002 (6.8 GBq) 6-8 weeks apart, followed by an interval PSMA PET/CT in 4-6 weeks and dose-adapted SBRT to all sites of disease 1-2 weeks later. The primary endpoint is progression-free survival. Secondary endpoints are radiographic and prostate-specific antigen-based progression, acute and late physician-scored toxicity, patient-reported quality of life, ADT-free survival, time to progression, overall survival, locoregional control, and duration of response. Enrolment in the study commenced in September 2022.

RESULTS AND CONCLUSIONS

The addition of ¹⁷⁷ Lu-PNT2002 to metastasis-directed therapy alone may potentially further forestall disease progression. The results of this Phase 2 trial will determine, for the first time in a randomized fashion, the added benefit of ¹⁷⁷ Lu-PNT2002 to SBRT in patients with oligorecurrent mHSPC.

Sequencing of Androgen-Deprivation Therapy of Short Duration With Radiotherapy for Nonmetastatic Prostate Cancer (SANDSTORM): A Pooled Analysis of 12 Randomized Trials

PURPOSE

The sequencing of androgen-deprivation therapy (ADT) with radiotherapy (RT) may affect outcomes for prostate cancer in an RT-field size-dependent manner. Herein, we investigate the impact of ADT sequencing for men receiving ADT with prostate-only RT (PORT) or whole-pelvis RT (WPRT).

MATERIALS AND METHODS

Individual patient data from 12 randomized trials that included patients receiving neoadjuvant/concurrent or concurrent/adjuvant short-term ADT (4-6 months) with RT for localized disease were obtained from the Meta-Analysis of Randomized trials in Cancer of the Prostate consortium. Inverse probability of treatment weighting (IPTW) was performed with propensity scores derived from age, initial prostate-specific antigen, Gleason score, T stage, RT dose, and mid-trial enrollment year. Metastasis-free survival (primary end point) and overall survival (OS) were assessed by IPTW-adjusted Cox regression models, analyzed independently for men receiving PORT versus WPRT. IPTW-adjusted Fine and Gray competing risk models were built to evaluate distant metastasis (DM) and prostate cancer-specific mortality.

RESULTS

Overall, 7,409 patients were included (6,325 neoadjuvant/concurrent and 1,084 concurrent/adjuvant) with a median follow-up of 10.2 years (interquartile range, 7.2-14.9 years). A significant interaction between ADT sequencing and RT field size was observed for all end points (P interaction < .02 for all) except OS. With PORT (n = 4,355), compared with neoadjuvant/concurrent ADT, concurrent/adjuvant ADT was associated with improved metastasis-free survival (10-year benefit 8.0%, hazard ratio [HR], 0.65; 95% CI, 0.54 to 0.79; P < .0001), DM (subdistribution HR, 0.52; 95% CI, 0.33 to 0.82; P = .0046), prostate cancer-specific mortality (subdistribution HR, 0.30; 95% CI, 0.16 to 0.54; P < .0001), and OS (HR, 0.69; 95% CI, 0.57 to 0.83; P = .0001). However, in patients receiving WPRT (n = 3,049), no significant difference in any end point was observed in regard to ADT sequencing except for worse DM (HR, 1.57; 95% CI, 1.20 to 2.05; P = .0009) with concurrent/adjuvant ADT.

CONCLUSION

ADT sequencing exhibits a significant impact on clinical outcomes with a significant interaction with field size. Concurrent/adjuvant ADT should be the standard of care where short-term ADT is indicated in combination with PORT.

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.

Experience of Telemedicine Visits in Radiation Oncology During the COVID-19 Pandemic: A US National Survey and Lessons Learned for Incorporating Telemedicine Post-COVID-19

Purpose

We sought to survey the attitudes and perceptions of US radiation oncologists toward the adoption of telemedicine during the COVID-19 pandemic and offer suggestions for its integration in the postpandemic era.

Methods and Materials

A 25-question, anonymous online survey was distributed nationwide to radiation oncologists.

Results

One hundred and twenty-one respondents completed the survey, with 92% from academia. Overall, 79% worked at institutions that had implemented a work-from-home policy, with which 74% were satisfied. Despite nearly all visit types being conducted in-person before COVID-19, 25%, 41%, and 5% of the respondents used telemedicine for more than half of their new consultations, follow-up, and on-treatment visits, respectively, during the COVID-19 pandemic. Most (83%) reported being comfortable integrating telemedicine. Although telemedicine was appreciated as being more convenient for patients (97%) and reducing transmission of infectious agents (83%), the most commonly perceived disadvantages were difficulty in performing physical examinations (90%), patients' inability to use technology adequately (74%), and technical malfunctions (72%). Compared with in-person visits, telemedicine was felt to be inferior in establishing a personal connection during consultation (90%) and assessing for toxicity while on-treatment (88%) and during follow-up (70%). For follow-up visits, genitourinary and thoracic were perceived as most appropriate for telemedicine while gynecologic and head and neck were considered the least appropriate. Overall, 70% were in favor of more telemedicine, even after pandemic is over.

Conclusions

Telemedicine will likely remain part of the radiation oncology workflow in most clinics after the pandemic. It should be used in conjunction with in-person visits, and may be best used for conducting follow-up visits in certain disease sites such as genitourinary and thoracic malignancies.

Local Failure Events in Prostate Cancer Treated with Radiotherapy: A Pooled Analysis of 18 Randomized Trials from the Meta-analysis of Randomized Trials in Cancer of the Prostate Consortium (LEVIATHAN)

CONTEXT

The prognostic importance of local failure after definitive radiotherapy (RT) in National Comprehensive Cancer Network intermediate- and high-risk prostate cancer (PCa) patients remains unclear.

OBJECTIVE

To evaluate the prognostic impact of local failure and the kinetics of distant metastasis following RT.

EVIDENCE ACQUISITION

A pooled analysis was performed on individual patient data of 12 533 PCa (6288 high-risk and 6245 intermediate-risk) patients enrolled in 18 randomized trials (conducted between 1985 and 2015) within the Meta-analysis of Randomized Trials in Cancer of the Prostate Consortium. Multivariable Cox proportional hazard (PH) models were developed to evaluate the relationship between overall survival (OS), PCa-specific survival (PCSS), distant metastasis-free survival (DMFS), and local failure as a time-dependent covariate. Markov PH models were developed to evaluate the impact of specific transition states.

EVIDENCE SYNTHESIS

The median follow-up was 11 yr. There were 795 (13%) local failure events and 1288 (21%) distant metastases for high-risk patients and 449 (7.2%) and 451 (7.2%) for intermediate-risk patients, respectively. For both groups, 81% of distant metastases developed from a clinically relapse-free state (cRF state). Local failure was significantly associated with OS (hazard ratio [HR] 1.17, 95% confidence interval [CI] 1.06-1.30), PCSS (HR 2.02, 95% CI 1.75-2.33), and DMFS (HR 1.94, 95% CI 1.75-2.15, p < 0.01 for all) in high-risk patients. Local failure was also significantly associated with DMFS (HR 1.57, 95% CI 1.36-1.81) but not with OS in intermediate-risk patients. Patients without local failure had a significantly lower HR of transitioning to a PCa-specific death state than those who had local failure (HR 0.32, 95% CI 0.21-0.50, p < 0.001). At later time points, more distant metastases emerged after a local failure event for both groups.

CONCLUSIONS

Local failure is an independent prognosticator of OS, PCSS, and DMFS in high-risk and of DMFS in intermediate-risk PCa. Distant metastasis predominantly developed from the cRF state, underscoring the importance of addressing occult microscopic disease. However a "second wave" of distant metastases occurs subsequent to local failure events, and optimization of local control may reduce the risk of distant metastasis.

PATIENT SUMMARY

Among men receiving definitive radiation therapy for high- and intermediate-risk prostate cancer, about 10% experience local recurrence, and they are at significantly increased risks of further disease progression. About 80% of patients who develop distant metastasis do not have a detectable local recurrence preceding it.

High-dose Radiotherapy or Androgen Deprivation Therapy (HEAT) as Treatment Intensification for Localized Prostate Cancer: An Individual Patient-data Network Meta-analysis from the MARCAP Consortium

BACKGROUND

The relative benefits of radiotherapy (RT) dose escalation and the addition of short-term or long-term androgen deprivation therapy (STADT or LTADT) in the treatment of prostate cancer are unknown.

OBJECTIVE

To perform a network meta-analysis (NMA) of relevant randomized trials to compare the relative benefits of RT dose escalation ± STADT or LTADT.

DESIGN, SETTING, AND PARTICIPANTS

An NMA of individual patient data from 13 multicenter randomized trials was carried out for a total of 11862 patients. Patients received one of the six permutations of low-dose RT (64 to <74 Gy) ± STADT or LTADT, high-dose RT (≥74 Gy), or high-dose RT ± STADT or LTADT.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSES

Metastasis-free survival (MFS) was the primary endpoint. Frequentist and Bayesian NMAs were performed to rank the various treatment strategies by MFS and biochemical recurrence-free survival (BCRFS).

RESULTS AND LIMITATIONS

Median follow-up was 8.8 yr (interquartile range 5.7-11.5). The greatest relative improvement in outcomes was seen for addition of LTADT, irrespective of RT dose, followed by addition of STADT, irrespective of RT dose. RT dose escalation did not improve MFS either in the absence of ADT (hazard ratio [HR] 0.97, 95% confidence interval [CI] 0.80-1.18) or with STADT (HR 0.99, 95% CI 0.8-1.23) or LTADT (HR 0.94, 95% CI 0.65-1.37). According to P-score ranking and rankogram analysis, high-dose RT + LTADT was the optimal treatment strategy for both BCRFS and longer-term outcomes.

CONCLUSIONS

Conventionally escalated RT up to 79.2 Gy, alone or in the presence of ADT, does not improve MFS, while addition of STADT or LTADT to RT alone, regardless of RT dose, consistently improves MFS. RT dose escalation does provide a high probability of improving BCRFS and, provided it can be delivered without compromising quality of life, may represent the optimal treatment strategy when used in conjunction with ADT.

PATIENT SUMMARY

Using a higher radiotherapy dose when treating prostate cancer does not reduce the chance of developing metastases or death, but it does reduce the chance of having a rise in prostate-specific antigen (PSA) signifying recurrence of cancer. Androgen deprivation therapy improves all outcomes. A safe increase in radiotherapy dose in conjunction with androgen deprivation therapy may be the optimal treatment.

M2 macrophage increase in prostate adenocarcinoma after high-dose rate brachytherapy

271

Background: Brachytherapy delivers high doses of hypofractionated radiation (RT) internally within the prostate tumor. While radiation has been shown to exhibit immunomodulatory effects, the success of combining radiation and immunotherapy in prostate cancer has been limited. M2 macrophages can contribute to an immunosuppressive tumor environment, and we therefore hypothesize that radiation may increase the abundance of M2 macrophage in the prostate tumor immune infiltrate. Methods: 10 Patients with intermediate risk prostate cancer (age 51-78; 7 GS 3+4, 3 GS 4+3) underwent high-dose rate brachytherapy (2 implants, 13.5Gy per implant, 1 week apart). Patients consented to biopsies before each fraction at the first and second implant. Bulk RNA-seq gene expression was performed on formalin-fixed, paraffin-embedded pre- vs. post-RT tumor samples, and then analyzed with a machine learning deconvolution model to resolve immune cell abundances. CD68+CD163+ M2 macrophages were analyzed with multiplex immunohistochemistry and quantified with tissue analysis software. Paired t-test was used to compare M2 macrophage abundance pre- versus post-RT. Results: Bulk RNA-seq deconvolution demonstrated that the most prevalent immune cell types in the pre-RT samples were resting CD4 memory T cells (39.7%), resting mast cells (38.5%), and M2 macrophages (30.4%), while those in the post-RT samples were M2 Macrophages (78.7%), resting mast cells (58.1%), and resting CD4 memory T cells (48%). M2 macrophages demonstrated the greatest increase, which was corroborated by multiplex IHC: average CD68+CD163+ cell counts were significantly elevated after RT (pre-RT 63.7 vs. post-RT 200.1 per mm2, p=0.015). Conclusions: Hypofractionated radiation increases the immunosuppressive M2 macrophage population in prostate cancer, which may present a therapeutic target to augment the efficacy of radiation and immunotherapy combinations.

Local failure, distant metastasis, and survival after definitive radiotherapy for intermediate- and high-risk prostate cancer: An individual patient-level meta-analysis of 18 randomized trials

277

Background: The prognostic importance of local failure (LF) after definitive radiotherapy (RT) in patients with NCCN intermediate- (IRPCa) and high-risk prostate cancer (HRPCa) remains unclear, particularly given the likelihood that occult distant metastases (DMs) at presentation may be the true driver of natural history. Here, we leverage individual patient data (IPD) from 18 randomized control trials (RCTs) to evaluate the prognostic impact of LF and the kinetics of DM after RT. Methods: IPD for 18 RCTs were obtained from the Meta-Analysis of Randomized trials in Cancer of the Prostate (MARCAP) Consortium, comprising a total of 12533 patients (6288 HRPCa & 6245 IRPCa). Multivariable Cox proportional hazards (PH) models were developed to evaluate the relationship between overall survival (OS), PCa-specific survival (PCSS), DM-free survival (DMFS) & LF as a time-dependent covariate, adjusted for clinicodemographic parameters. Markov PH models, defined via transitions between 4 states, were developed to evaluate the aforementioned relationship. Proportional hazards assumption was imposed and examined for both models. Time is from randomization. Results: Median follow-up was 9.1 years. There were 795 (13%) LF & 1288 (21%) DM events for patients with HRPCa; these numbers were 449 (7%) & 451 (7%) for IRPCa. For HRPCa & IRPCa, 81% and 81% of DMs developed from a clinically relapse-free state (cRFS), with a median time of 46 and 60 months, respectively (p < 0.0001). 39% & 13% of DM events occurred within 2 years after RT for HRPCa & IRPCa, respectively. At later time points, DM events were more likely to emerge after an LF event for both HRPCa (9% vs. 34% between 0-2 vs. 8-10 years post-RT, p = 0.001) and IRPCa (10% vs. 34% between 0-2 vs. 8-10 years post-RT, p = 0.008). LF was significantly associated with OS (hazard ratio [HR] 1.17, 95% confidence interval [CI] 1.06–1.30), PCSS (HR 2.02, 95% CI 1.75-2.33) & DMFS (HR 1.94, 95% CI 1.75–2.15) (p < 0.01 for all) in patients with HRPCa. LF was also significantly associated with DMFS (HR 1.57, 95% CI 1.36–1.81) but not OS in patients with IRPCa. Patients who had not transitioned to the LF state had a significantly lower HR of transitioning to a PCa-specific death state than those who transitioned to the LF state (HR 0.32, 95% CI 0.21–0.50, p < 0.001). Conclusions: LF is an independent prognosticator of OS, PCSS & DMFS in HRPCa and of DMFS in IRPCa. The predominant mode of DM development is from the cRFS state, underscoring the importance of accurate upfront staging & systemic therapy. However, particularly at late time points, an increasing proportion of DM events originated after diagnosis of a LF, constituting a “second wave” of DM events. This suggests that optimizing local control is also important, though the majority of DM events appear prior to a clinically-detected LF.

Magnetic resonance imaging-guided versus computed tomography-guided stereotactic body radiotherapy for prostate cancer (MIRAGE): Interim analysis of a phase III randomized trial

255

Background: Magnetic resonance imaging (MRI) guidance offers several theoretical advantages over computed tomography (CT) guidance in the context of stereotactic body radiotherapy (SBRT) for intact prostate cancer. Here we report the results of an interim analysis of the phase III MIRAGE trial, which directly compared MRI- and CT-guidance with a pragmatic primary endpoint of acute grade ≥2 genitourinary (GU) toxicity. Methods: MIRAGE is a single center, randomized phase 3 trial. Men undergoing SBRT for localized prostate cancer were randomly assigned to either CT-guidance or MRI-guidance. Planning margins of 4 mm (CT-arm) and 2 mm (MRI-arm) were placed around the prostate and proximal seminal vesicles, and this volume received 40 Gy in five fractions. Elective nodal radiotherapy and rectal spacers were allowed per physician discretion. The primary outcome was the incidence of acute (i.e., within 90 days of SBRT) grade ≥2 GU physician-reported toxicity (by CTCAE version 4.03). Secondary outcomes of interest included the incidence of acute grade ≥2 GU physician-reported toxicity, changes in IPSS scores at 1 and 3 months, and changes in EPIC-26 bowel domain summary scores at 1 and 3 months. A pre-specified efficacy analysis was planned once the 100th patient was eligible for evaluation of the primary endpoint. Results: On 9/1/2021, 100 patients became eligible for evaluation for the interim analysis (51 CT arm, 49 MRI arm). Acute grade ≥2 GU toxicity was significantly reduced in men receiving MRI-guided SBRT (incidence of 24 (47.1%) vs. 11 (22.4%), p = 0.01). Acute grade ≥2 GI toxicity was also significantly reduced in men receiving MRI-guided SBRT (incidence of 7 (13.7%) vs. 0 (0%), p = 0.01.). The increase in IPSS scores from baseline was significantly higher in men receiving CT-guided SBRT at 1 month post-SBRT (median change of 10 vs. 6, p = 0.03), but not at 3 months (median change of 3 vs. 2, p = 0.3). The decrement in EPIC-26 bowel domain scores was significantly greater at 1 month in men receiving CT-guided SBRT (median change of -8.3 vs. 0, p = 0.03), but not at 3 months (median change of -2.3 vs. 0, p = 0.4). Given the large primary endpoint signal seen, our protocol was amended to reduce the projected sample size to 154 while still maintaining 89% power to detect a difference. Conclusions: This interim analysis demonstrates a statistically significant reduction in acute grade ≥2 GU toxicity with MRI-guidance versus CT-guidance in the context of prostate SBRT. Patient-reported urinary and bowel function metrics are also better preserved at the 1 month time point with MRI-guidance, though this difference dissipates (potentially due to side-effect management) at the 3 month time point. Accrual has been completed as of October 2021 and a final analysis for the primary endpoint is anticipated in early 2022. Clinical trial information: NCT04384770.

A Prospective Phase II Study of Automated Non-Coplanar VMAT for Recurrent Head and Neck Cancer: Initial Report of Feasibility, Safety, and Patient-Reported Outcomes

Simple Summary

The delivery of higher radiation doses has been shown to increase local control, and ultimately survival, for head and neck cancer patients, but highly conformal dose distributions are necessary to minimize normal tissue toxicity. Varian’s HyperArc non-coplanar automated treatment planning and delivery technique has been shown to improve dose conformity for intracranial treatment, but its safety and efficacy for head and neck cancer treatment has yet to be verified. This study evaluates the initial results of a prospective clinical trial using HyperArc for recurrent head and neck cancer patients. We demonstrated that HyperArc can enable significant tumor dose escalation compared to conventional volumetric modulated arc therapy (VMAT) planning while minimizing the dose to organs at risk. Treatment delivery was feasible and safe, with minimal treatment-related toxicities and positive patient-reported quality of life measures.

Abstract

This study reports the initial results for the first 15 patients on a prospective phase II clinical trial exploring the safety, feasibility, and efficacy of the HyperArc technique for recurrent head and neck cancer treatment. Eligible patients were simulated and planned with both conventional VMAT and HyperArc techniques and the plan with superior dosimetry was selected for treatment. Dosimetry, delivery feasibility and safety, treatment-related toxicity, and patient-reported quality of life (QOL) were all evaluated. HyperArc was chosen over conventional VMAT for all 15 patients and enabled statistically significant increases in dose conformity (R50% reduced by 1.2 ± 2.1, p < 0.05) and mean PTV and GTV doses (by 15.7 ± 4.9 Gy, p < 0.01 and 17.1 ± 6.0 Gy, p < 0.01, respectively). The average HyperArc delivery was 2.8 min longer than conventional VMAT (p < 0.01), and the mean intrafraction motion was ≤ 0.5 ± 0.4 mm and ≤0.3 ± 0.1°. With a median follow-up of 12 months, treatment-related toxicity was minimal (only one grade 3 acute toxicity above baseline) and patient-reported QOL metrics were favorable. HyperArc enabled superior dosimetry and significant target dose escalation compared to conventional VMAT planning, and treatment delivery was feasible, safe, and well-tolerated by patients.

Comparison of Response to Definitive Radiotherapy for Localized Prostate Cancer in Black and White Men: A Meta-analysis

IMPORTANCE

Black men have a 2-fold increased risk of dying from prostate cancer compared with White men. However, race-specific differences in response to initial treatment remain unknown.

OBJECTIVE

To compare overall and treatment-specific outcomes of Black and White men with localized prostate cancer receiving definitive radiotherapy (RT).

DATA SOURCES

A systematic search was performed of relevant published randomized clinical trials conducted by the NRG Oncology/Radiation Therapy Oncology Group between January 1, 1990, and December 31, 2010. This meta-analysis was performed from July 1, 2019, to July 1, 2021.

STUDY SELECTION

Randomized clinical trials of definitive RT for patients with localized prostate cancer comprising a substantial number of Black men (self-identified race) enrolled that reported on treatment-specific and overall outcomes.

DATA EXTRACTION AND SYNTHESIS

Individual patient data were obtained from 7 NRG Oncology/Radiation Therapy Oncology Group randomized clinical trials evaluating definitive RT with or without short- or long-term androgen deprivation therapy. Unadjusted Fine-Gray competing risk models, with death as a competing risk, were developed to evaluate the cumulative incidences of end points. Cox proportional hazards models were used to evaluate differences in all-cause mortality and the composite outcome of distant metastasis (DM) or death. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was followed.

MAIN OUTCOMES AND MEASURES

Subdistribution hazard ratios (sHRs) of biochemical recurrence (BCR), DM, and prostate cancer-specific mortality (PCSM).

RESULTS

A total of 8814 patients (1630 [18.5%] Black and 7184 [81.5%] White) were included; mean (SD) age was 69.1 (6.8) years. Median follow-up was 10.6 (IQR, 8.0-17.8) years for surviving patients. At enrollment, Black men were more likely to have high-risk disease features. However, even without adjustment, Black men were less likely to experience BCR (sHR, 0.88; 95% CI, 0.58-0.91), DM (sHR, 0.72; 95% CI, 0.58-0.91), or PCSM (sHR, 0.72; 95% CI, 0.54-0.97). No significant differences in all-cause mortality were identified (HR, 0.99; 95% CI, 0.92-1.07). Upon adjustment, Black race remained significantly associated with improved BCR (adjusted sHR, 0.79; 95% CI, 0.72-0.88; P < .001), DM (adjusted sHR, 0.69; 95% CI, 0.55-0.87; P = .002), and PCSM (adjusted sHR, 0.68; 95% CI, 0.50-0.93; P = .01).

CONCLUSIONS AND RELEVANCE

The findings of this meta-analysis suggest that Black men enrolled in randomized clinical trials present with more aggressive disease but have better BCR, DM, and PCSM with definitive RT compared with White men, suggesting that other determinants of outcome, such as access to care, are important factors of achieving racial equity.

Performance of a Prostate-Specific Membrane Antigen Positron Emission Tomography/Computed Tomography-Derived Risk-Stratification Tool for High-risk and Very High-risk Prostate Cancer

IMPORTANCE

Prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) can detect low-volume, nonlocalized (ie, regional or metastatic) prostate cancer that was occult on conventional imaging. However, the long-term clinical implications of PSMA PET/CT upstaging remain unclear.

OBJECTIVES

To evaluate the prognostic significance of a nomogram that models an individual's risk of nonlocalized upstaging on PSMA PET/CT and to compare its performance with existing risk-stratification tools.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included patients diagnosed with high-risk or very high-risk prostate cancer (ie, prostate-specific antigen [PSA] level >20 ng/mL, Gleason score 8-10, and/or clinical stage T3-T4, without evidence of nodal or metastatic disease by conventional workup) from April 1995 to August 2018. This multinational study was conducted at 15 centers. Data were analyzed from December 2020 to March 2021.

EXPOSURES

Curative-intent radical prostatectomy (RP), external beam radiotherapy (EBRT), or EBRT plus brachytherapy (BT), with or without androgen deprivation therapy.

MAIN OUTCOMES AND MEASURES

PSMA upstage probability was calculated from a nomogram using the biopsy Gleason score, percentage positive systematic biopsy cores, clinical T category, and PSA level. Biochemical recurrence (BCR), distant metastasis (DM), prostate cancer-specific mortality (PCSM), and overall survival (OS) were analyzed using Fine-Gray and Cox regressions. Model performance was quantified with the concordance (C) index.

RESULTS

Of 5275 patients, the median (IQR) age was 66 (60-72) years; 2883 (55%) were treated with RP, 1669 (32%) with EBRT, and 723 (14%) with EBRT plus BT; median (IQR) PSA level was 10.5 (5.9-23.2) ng/mL; 3987 (76%) had Gleason grade 8 to 10 disease; and 750 (14%) had stage T3 to T4 disease. Median (IQR) follow-up was 5.1 (3.1-7.9) years; 1221 (23%) were followed up for at least 8 years. Overall, 1895 (36%) had BCR, 851 (16%) developed DM, and 242 (5%) died of prostate cancer. PSMA upstage probability was significantly prognostic of all clinical end points, with 8-year C indices of 0.63 (95% CI, 0.61-0.65) for BCR, 0.69 (95% CI, 0.66-0.71) for DM, 0.71 (95% CI, 0.67-0.75) for PCSM, and 0.60 (95% CI, 0.57-0.62) for PCSM (P < .001). The PSMA nomogram outperformed existing risk-stratification tools, except for similar performance to Staging Collaboration for Cancer of the Prostate (STAR-CAP) for PCSM (eg, DM: PSMA, 0.69 [95% CI, 0.66-0.71] vs STAR-CAP, 0.65 [95% CI, 0.62-0.68]; P < .001; Memorial Sloan Kettering Cancer Center nomogram, 0.57 [95% CI, 0.54-0.60]; P < .001; Cancer of the Prostate Risk Assessment groups, 0.53 [95% CI, 0.51-0.56]; P < .001). Results were validated in secondary cohorts from the Surveillance, Epidemiology, and End Results database and the National Cancer Database.

CONCLUSIONS AND RELEVANCE

These findings suggest that PSMA upstage probability is associated with long-term, clinically meaningful end points. Furthermore, PSMA upstaging had superior risk discrimination compared with existing tools. Formerly occult, PSMA PET/CT-detectable nonlocalized disease may be the main driver of outcomes in high-risk patients.

Refining the definition of biochemical failure in the era of stereotactic body radiation therapy for prostate cancer: The Phoenix definition and beyond

BACKGROUND AND PURPOSE

The Phoenix definition for biochemical failure (BCF) after radiotherapy uses nadir PSA (nPSA) + 2 ng/mL to classify a BCF and was derived from conventionally fractionated radiotherapy, which produces significantly higher nPSAs than stereotactic body radiotherapy (SBRT). We investigated whether an alternative nPSA-based threshold could be used to define post-SBRT BCFs.

MATERIALS AND METHODS

PSA kinetics data on 2038 patients from 9 institutions were retrospectively analyzed for low- and intermediate-risk PCa patients treated with SBRT without ADT. We evaluated the performance of various nPSA-based definitions. We also investigated the relationship of relative PSA decline (rPSA, PSA_18month/PSA_6month) and timing of reaching nPSA + 2 with BCF.

RESULTS

Median follow-up was 71.9 months. BCF occurred in 6.9% of patients. Median nPSA was 0.16 ng/mL. False positivity of nPSA + 2 was 30.2%, compared to 40.9%, 57.8%, and 71.0% for nPSA + 1.5, nPSA + 1.0, and nPSA + 0.5, respectively. Among patients with BCF, the median lead time gained from an earlier nPSA + threshold definition over the Phoenix definition was minimal. Patients with BCF had significantly lower rates of early PSA decline (mean rPSA 1.19 vs. 0.39, p < 0.0001) and were significantly more likely to reach nPSA + 2 ≥ 18 months (83.3% vs. 21.1%, p < 0.0001). The proposed criterion (rPSA ≥ 2.6 or nPSA + 2 ≥ 18 months) had a sensitivity and specificity of 92.4% and 81.5%, respectively, for predicting BCF in patients meeting the Phoenix definition and decreased its false positivity to 6.4%.

CONCLUSION

The Phoenix definition remains an excellent definition for BCF post-SBRT. Its high false positivity can be mitigated by applying additional criteria (rPSA ≥ 2.6 or time to nPSA + 2 ≥ 18 months).

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.

Association between percentage of positive biopsy cores and risk of pelvic lymph node involvement in prostate cancer

205

Background: Commonly used tools for predicting the risk of pelvic lymph node involvement (LNI) in prostate cancer often do not incorporate information on the percentage of positive biopsy cores (PPB). To better inform the use of elective nodal irradiation in the definitive treatment of prostate cancer, we examined the association between PPB and risk of pathologic pelvic LNI in men with prostate cancer who underwent radical prostatectomy (RP). Methods: We identified 109,577 men from the National Cancer Database who were diagnosed in 2010-2015 with cN0M0 prostate cancer, had 6-24 cores sampled at biopsy, and underwent RP with pathologic nodal evaluation. Multivariable logistic regression was used to examine the association between PPB and the likelihood of having ≥1 positive pelvic lymph node, adjusting for other known clinicopathologic prognostic variables. Results: Overall, 4.0% (4,340) of the cohort was found to have pelvic LNI at the time of RP. Higher PPB was associated with an increased risk of pelvic LNI (adjusted odds ratio [AOR] 1.75 for 25.1-50.0% PPB, 2.63 for 50.1-75.0% PPB, and 4.49 for 75.1-100.0% PPB vs. ≤25.0% PPB, all P<0.001). Notably, men with Gleason 8 disease and ≤25.0% PPB only had a 3.6% risk of pelvic LNI, whereas men with Gleason 9-10 disease and 75.1-100.0% PPB had a 32.6% risk (Table). Other factors associated with the likelihood of pelvic LNI included a higher biopsy Gleason score (AOR 1.43 for Gleason 8 and 2.84 for Gleason 9-10 vs. Gleason 4+3, both P<0.001), more advanced clinical tumor stage (AOR 1.48 for cT2, 1.97 for cT3, and 3.87 for cT4 vs. cT1, all P<0.001), and a higher PSA (AOR 1.90 for 10.0-19.9 ng/mL, 2.40 for 20.0-39.9 ng/mL, and 2.60 for ≥40.0 ng/mL vs. <10.0 ng/mL, all P<0.001), but not more advanced age (AOR 0.98 for >62 years [median] vs. ≤62 years, P=0.59) or black vs. white race (AOR 0.99, P=0.92). Conclusions: There was a statistically significant and clinically relevant association between increasing PPB and a higher risk of pelvic LNI. As the ongoing RTOG 0924 randomized trial matures, clinicians should consider incorporating information on PPB in determining which patients with prostate cancer may benefit from receiving radiation therapy to the pelvic lymph nodes. [Table: see text]

Identifying the Best Candidates for Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography as the Primary Staging Approach Among Men with High-risk Prostate Cancer and Negative Conventional Imaging

Prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/computed tomography (CT) is an emerging imaging modality with greater sensitivity and specificity over conventional imaging for prostate cancer (PCa) staging. Using data from two prospective trials (NCT03368547 and NCT04050215), we explored predictors of overall upstaging (nodal and metastatic) by PSMA PET/CT among patients with cN0M0 National Comprehensive Cancer Network high-risk PCa on conventional imaging (n = 213). Overall, 21.1%, 8.9%, and 23.9% of patients experienced nodal, metastatic, and overall upstaging, respectively, without histologic confirmation. On multivariable analysis, Gleason grade group (GG) and percent positive core (PPC) on systematic biopsy significantly predict overall upstaging (odds ratio [OR] 2.15, 95% confidence interval [CI] 1.33-3.45; p =  0.002; and OR 1.03, 95% CI 1.01-1.04; p <  0.001). Overall upstaging was significantly more frequent among men with GG 5 disease (33.0% vs. 17.6%; p =  0.0097) and PPC ≥50% (33.0% vs 15.0%; p =  0.0020). We constructed a nomogram that predicts overall upstaging using initial prostate-specific antigen, PPC, GG, and cT stage, with coefficients estimated from a standard logistic regression model (using maximum likelihood estimation). It is internally validated with a tenfold cross-validated area under the receiver operating characteristic curve estimated at 0.74 (95% CI 0.67-0.82). In our cohort, 90% of patients who had a nomogram-estimated risk below the cutoff of 22% for overall upstaging could have been spared PSMA PET/CT as our model correctly predicted no upstaging. In other words, the predictive model only missed 10% of patients who would otherwise have benefitted from PSMA PET/CT. PATIENT SUMMARY: We analyzed predictors of overall upstaging (lymph node or/and metastasis) by prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) from conventional imaging in men with high-risk prostate cancer undergoing initial staging deemed free of disease in the lymph nodes and distant metastasis by conventional imaging techniques. We found that the pathologic grade and disease burden in a prostate biopsy are associated with upstaging. We also developed a tool that predicts the probability of upstaging according to an individual patient's characteristics. Our study may help in defining patient groups who are most likely to benefit from the addition of a PSMA PET/CT scan.

MR-Guided Radiotherapy for Prostate Cancer

External beam radiotherapy remains the primary treatment modality for localized prostate cancer. The radiobiology of prostate carcinoma lends itself to hypofractionation, with recent studies showing good outcomes with shorter treatment schedules. However, the ability to accurately deliver hypofractionated treatment is limited by current image-guided techniques. Magnetic resonance imaging is the main diagnostic tool for localized prostate cancer and its use in the therapeutic setting offers anatomical information to improve organ delineation. MR-guided radiotherapy, with daily re-planning, has shown early promise in the accurate delivery of radiotherapy. In this article, we discuss the shortcomings of current image-guidance strategies and the potential benefits and limitations of MR-guided treatment for prostate cancer. We also recount present experiences of MR-linac workflow and the opportunities afforded by this technology.

Response to R-CHOP in HPV-related squamous cell carcinoma of base of tongue: a case report

Background

Synchronous squamous cell carcinoma of the head and neck (HNSCC) and non-Hodgkin's lymphoma is a rare clinical scenario. It is unknown whether the R-CHOP chemotherapy for lymphoma would also be active against HNSCC. Herein, we present such a case and a review of the literature.

Case presentation

A 64 year-old female presented with painless jaundice. CT demonstrated a retroperitoneal mass and pathology showed follicular lymphoma. A base-of-tongue HPV⁺ squamous cell carcinoma was found incidentally on staging CT. R-CHOP chemotherapy was initiated. After 3 cycles of R-CHOP the lymphoma had a complete metabolic response and, unexpectedly, the HNSCC also demonstrated excellent response. The patient received another 3 cycles followed by radiation to the HNSCC and to date is in remission for both cancers.

Conclusions

This case highlights the exquisite sensitivity of HPV-related HNSCC, which should be taken into consideration in treatment prioritization of a concurrent diagnosis of a second cancer.

Serine racemase regulated by binding to stargazin and PSD-95: potential N-methyl-D-aspartate-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (NMDA-AMPA) glutamate neurotransmission cross-talk

D-Serine, an endogenous co-agonist for the glycine site of the synaptic NMDA glutamate receptor, regulates synaptic plasticity and is implicated in schizophrenia. Serine racemase (SR) is the enzyme that converts L-serine to D-serine. In this study, we demonstrate that SR interacts with the synaptic proteins, postsynaptic density protein 95 (PSD-95) and stargazin, forming a ternary complex. SR binds to the PDZ3 domain of PSD-95 through the PDZ domain ligand at its C terminus. SR also binds to the C terminus of stargazin, which facilitates the cell membrane localization of SR and inhibits its activity. AMPA receptor activation internalizes SR and disrupts its interaction with stargazin, therefore derepressing SR activity, leading to more D-serine production and potentially facilitating NMDA receptor activation. These interactions regulate the enzymatic activity as well as the intracellular localization of SR, potentially coupling the activities of NMDA and AMPA receptors. This shuttling of a neurotransmitter synthesizing enzyme between two receptors appears to be a novel mode of synaptic regulation.

Surgical outcomes of craniocervial junction meningiomas: a series of 22 consecutive patients

OBJECTIVE

We present our experience in managing craniocervical junction meningiomas and discuss various surgical approaches and outcomes.

METHODS

We retrospectively reviewed 22 consecutive cases of craniocervical junction meningiomas operated on between August 1995 and May 2012.

RESULTS

There were 15 female and 7 male patients (mean age: 54 years). Meningiomas were classified based on origin as spinocranial (7 cases) or craniospinal (15 cases). Additionally, the tumors were divided into anatomical location relative to the brainstem or spinal cord: there were 2 anterior tumors, 7 anterolateral, 12 lateral, and 1 posterolateral. Surgical approaches included the posterior midline suboccipital approach (9 cases), the far lateral approach (12 cases) and the lateral retrosigmoid approach (1 case). Gross-total resection was achieved in 45% of patients and subtotal in 55%. The most common post-operative complications were cranial nerve (CN) IX and X deficits. The mortality rate was 4.5%. There have been no recurrences to date with a mean follow-up was 46.5 months and the mean Karnofsky score at the last follow-up of 82.3. In this series, spinocranial tumors were detected at a smaller size (p=0.0724) and treated earlier (p=0.1398) than craniospinal tumors. They were associated with a higher rate of total resection (p=0.0007), fewer post-operative CN IX or X deficits (p=0.0053), and shorter hospitalizations (p=0.08).

CONCLUSION

Our experience suggests that posterior midline suboccipital or far-lateral approaches with minimal condylar drilling and vertebral artery mobilization were suitable for most cases in this series.

Comparison of outcomes by modality for critically ill patients requiring renal replacement therapy: a single-centre cohort study adjusting for time-varying illness severity and modality exposure

Prolonged intermittent renal replacement therapy (PIRRT) is a recently defined acute modality for critically ill patients, and in theory combines the superior detoxification and haemodynamic stability of continuous renal replacement therapy (CRRT) with the operational convenience and low cost of intermittent haemodialysis (iHD). We performed a retrospective cohort study for all critically ill adults treated with renal replacement therapy at our centre in Auckland, New Zealand from 1 January 2002 to 31 December 2008. The exposure of interest was modality (PIRRT, CRRT, iHD). Primary and secondary outcomes were patient mortality determined at hospital discharge and 90 days post renal replacement therapy inception, respectively. Co-variates included co-morbidity and baseline illness severity measured by Acute Physiology and Chronic Health Evaluation IV and Sepsis-Related Organ Failure Assessment (SOFA) and time-varying illness severity measured by daily SOFA scores. We used Marginal Structural Modelling to estimate mortality risk adjusting for both time-varying illness severity and modality exposure. A total of 146 patients with 633 treatment-days had sufficient data for modelling. With PIRRT as the reference, the adjusted hazard ratios for patient hospital mortality were 1.31 (0.60 to 2.90) for CRRT and 1.22 (0.21 to 2.29) for iHD. Corresponding estimates for mortality at 90 days were 0.96 (0.39 to 2.36) and 2.22 (0.49 to 10.11), respectively, reflecting the poorer longer-term prognosis of patients still on iHD at hospital discharge with delayed or non-recovery of acute kidney injury. Our study supports the recent increased use of PIRRT, which within limits can be regarded as safe and effective.

Protein kinase A-mediated 14-3-3 association impedes human Dapper1 to promote dishevelled degradation

Wnt signaling regulates embryo development and tissue homeostasis, and its deregulation leads to an array of diseases, including cancer. Dapper1 has been shown to be a key negative regulator of Wnt signaling. However, its function and regulation remain poorly understood. In this study, we report that 14-3-3β interacts with human Dapper1 (hDpr1). The interaction is dependent on protein kinase A (PKA)-mediated phosphorylation of hDpr1 at Ser-237 and Ser-827. 14-3-3β binding attenuates the ability of hDpr1 to promote Dishevelled (Dvl) degradation, thus enhancing Wnt signaling. We further provide evidence that PKA-mediated Dpr1 phosphorylation may contribute to growth and tumor formation of colon cancer Caco2 cells. Finally, we show that cyclooxygenase-2 expression and PKA activation are positively correlated with Dvl protein levels in colon cancer samples. Together, our findings establish a novel layer of regulation of Wnt signaling by PKA via the 14-3-3-Dpr1-Dvl axis.

Reverse engineering of bacterial chemotaxis pathway via frequency domain analysis

Chemotaxis is defined as a behavior involving organisms sensing attractants or repellents and leading towards or away from them. Therefore, it is possible to reengineer chemotaxis network to control the movement of bacteria to our advantage. Understanding the design principles of chemotaxis pathway is a prerequisite and an important topic in synthetic biology. Here, we provide guidelines for chemotaxis pathway design by employing control theory and reverse engineering concept on pathway dynamic design. We first analyzed the mathematical models for two most important kinds of E. coli chemotaxis pathway—adaptive and non-adaptive pathways, and concluded that the control units of the pathway de facto function as a band-pass filter and a low-pass filter, respectively, by abstracting the frequency response properties of the pathways. The advantage of the band-pass filter is established, and we demonstrate how to tune the three key parameters of it—A (max amplification), ω₁ (down cut-off frequency) and ω₂ (up cut-off frequency) to optimize the chemotactic effect. Finally, we hypothesized a similar but simpler version of the dynamic pathway model based on the principles discovered and show that it leads to similar properties with native E. coli chemotactic behaviors. Our study provides an example of simulating and designing biological dynamics in silico and indicates how to make use of the native pathway's features in this process. Furthermore, the characteristics we discovered and tested through reverse engineering may help to understand the design principles of the pathway and promote the design of artificial chemotaxis pathways.

[Changes in Galphaq/11 mediated signal transduction pathway in the aorta of two kidney one clip hypertensive rats]

The objective of this study was to investigate the role of signal transduction pathway mediated by Galphaq/11 of the aorta in blood pressure regulation during the development of two-kidney one clip (2K1C) Glodblatt hypertension in the rat. Levels of Galphaq/11-subunit and extracellular signal regulated kinase 1/2 (ERK1/2) of the aorta were measured by Western blot analysis at week 1, 2, 4 or 8 after operation. Phospholipase C (PLC) activity of the aorta was measured by using (3)H phosphatidylinostol (4,5) bisphosphate as a substrate. Both systolic and diastolic blood pressure increased markedly in 2K1C rats at week 2, 4 or 8, whereas, the increase in Galphaq/11 and ERK1/2 expression of the aorta began at week 1 after operation (increased by 57.53% and 40.16%, respectively), and maintained at a high level during week 2 8 compared with time matched controls (P<0.01). PLC activities in the aorta were also increased significantly in 2K1C groups at week 4 and 8 compared with the time matched controls (P<0.05). The results indicate that Galphaq/11-mediated signal transduction pathway of the aorta is activated in 2K1C hypertension, and may contribute to the initiation and maintenance of renal hypertension.

[The dynamic changes of NOSmRNA in endothelial cells of aortae and pulmonary arteries in rats under tail suspension]

Objective. Through the observations of dynamic changes of eNOSmRNA and iNOSmRNA in arterial endothelial cells of systematic circulation and pulmonary circulation under simulated weightlessness, to collect some data for studies of the adaptive mechanisms of local regulation in arterial systems. Method. Wistar rats were -30 degrees tail suspended to simulate the effects of weightlessness. The rats were randomly divided into three groups: control group (CON), 7-day tail suspension group (TS7) and 14-day tail suspension group (TS14). Changes of NOSmRNA expresses in endothelial cells of the thoracic aortae and pulmonary arteries were observed with in situ hybridization technique. Result. The eNOSmRNA and iNOSmRNA of thoracic aortic and pulmonary arterial endothelial cells in TS7 rats increased very significantly. The eNOSmRNA of thoracic aortic endothelial cells from TS14 rats returned to control level, but remained very significantly increased in pulmonary arteries. The iNOSmRNA in pulmonary arterial endothelial cells from TS14 rats decreased very significantly, but that in thoracic aortae returned to the control level. Conclusion. The responses of eNOSmRNA and iNOSmRNA in arterial endothelial cells of systematic circulation to tail suspension were similar, but they were different in pulmonary arterial endothelial cells, which might be due to the difference in the peak course of the shift of fluid from lower body entering the pulmonary or systematic circulation during initial period of simulated weightlessness. It could be a kind of important sign of depressed local regulative function under simulated weightlessness and might contribute to orthostatic intolerance after simulated weightlessness.

[The effect of lycium barbarum polysaccharide on vascular tension in two-kidney, one clip model of hypertension]

In the present study, the effects of lycium barbarum polysaccharide (LBP) on endothelial function in the two-kidney, one clip model of hypertension were observed. The results showed that the increase of blood pressure in hypertension rats (HR) could be prevented significantly by treatment with 10% LBP. In isolated aortic rings of LBP-treated rats, the contraction of phenylephrine (PE) was reduced as compared with HR rats. Removal of the endothelium abolished the difference of PE-induced vasoconstriction among groups. In vitro incubation of aortic rings from LBP-treated rats with methyl blue (MB) or N-nitro-L-arginine methyl ester (L-NAME) increased the magnitude of PE-induced contraction. Meanwhile the response to acetylcholine (ACh) was significantly increased in LBP-treated rats, but the response to nitroprusside had no significant difference among groups. Pretreatment with L-arginine partially restored ACh-induced relaxation in RH rats, but no effect in LBP-treated rats. These results suggested that the role of LBP in decreasing vasoconstriction to PE may be mediated by increase of the effects or/and production of endothelium-derived relaxation factor (EDRF). LBP increased formation of EDRF may be related to increase the substrate of EDRF.