First-line immune checkpoint inhibitor use in cisplatin-eligible patients with advanced urothelial carcinoma: a secular trend analysis.

Aim: Standard first-line treatment of advanced urothelial cell carcinoma involves cisplatin-based chemotherapy, with carboplatin or immune checkpoint inhibitor therapy (ICI) reserved for cisplatin-ineligible individuals. Methods: Using a large de-identified electronic health record-derived database of patients with advanced urothelial cell carcinoma in the USA, we examined trends in utilization of first-line systemic therapies in cisplatin-eligible patients from 1 January 2015 to 31 March 2018. Results: Among 1181 cisplatin-eligible patients, the quarterly proportion who received first-line ICI increased from 1 to 42% (ptrend <0.001), while the proportion who received cisplatin-based chemotherapy decreased from 53 to 33% (ptrend = 0.018). Patients receiving ICI were older than those receiving cisplatin (median age: 75 vs 68). Conclusion: Our analysis suggests rising off-label ICI use in cisplatin-eligible individuals, potentially because of ICI's favorable toxicity profile.

Comparative toxicity outcomes of proton-beam therapy versus intensity-modulated radiotherapy for prostate cancer in the postoperative setting.

BACKGROUND: Despite increasing utilization of proton-beam therapy (PBT) in the postprostatectomy setting, no data exist regarding toxicity outcomes relative to intensity-modulated radiotherapy (IMRT). The authors compared acute and late genitourinary (GU) and gastrointestinal (GI) toxicity outcomes in patients with prostate cancer (PC) who received treatment with postprostatectomy IMRT versus PBT. METHODS: With institutional review board approval, patients with PC who received adjuvant or salvage IMRT or PBT (70.2 gray with an endorectal balloon) after prostatectomy from 2009 through 2017 were reviewed. Factors including combined IMRT and PBT and/or concurrent malignancies prompted exclusion. A case-matched cohort analysis was performed using nearest-neighbor 3-to-1 matching by age and GU/GI disorder history. Logistic and Cox regressions were used to identify univariate and multivariate associations between toxicities and cohort/dosimetric characteristics. Toxicity-free survival (TFS) was assessed using the Kaplan-Meier method. RESULTS: Three hundred seven men (mean ± SD age, 59.7 ± 6.3 years; IMRT, n = 237; PBT, n = 70) were identified, generating 70 matched pairs. The median follow-up was 48.6 and 46.1 months for the IMRT and PBT groups, respectively. Although PBT was superior at reducing low-range (volumes receiving 10% to 40% of the dose, respectively) bladder and rectal doses (all P ≤ .01), treatment modality was not associated with differences in clinician-reported acute or late GU/GI toxicities (all P ≥ .05). Five-year grade ≥2 GU and grade ≥1 GI TFS was 61.1% and 73.7% for IMRT, respectively, and 70.7% and 75.3% for PBT, respectively; and 5-year grade ≥3 GU and GI TFS was >95% for both groups (all P ≥ .05). CONCLUSIONS: Postprostatectomy PBT minimized low-range bladder and rectal doses relative to IMRT; however, treatment modality was not associated with clinician-reported GU/GI toxicities. Future prospective investigation and ongoing follow-up will determine whether dosimetric differences between IMRT and PBT confer clinically meaningful differences in long-term outcomes.

Understanding the predictive value of continuous markers for censored survival data using a likelihood ratio approach.

BACKGROUND: The likelihood ratio function (LR), the ratio of conditional probabilities of obtaining a specific marker value among those with the event of interest over those without, provides an easily interpretable way to quantify the update of the risk prediction due to the knowledge of the marker value. The LR has been explored for both binary and continuous markers for binary events (e.g., diseased or not), however the use of the LR in censored data has not been fully explored. METHODS: We extend the concept of LR to a time-dependent LR (TD-LR) for survival outcomes that are subject to censoring. Estimation for the TD-LR is done using Kaplan-Meier estimation and a univariate Cox proportional hazards (PH) model. A "scale invariant" approach based on marker quantiles is provided to allow comparison of predictive values between markers with different scales. Relationships to time-dependent receiver-operator characteristic (ROC) curves, area under the curve (AUC), and optimal cut-off values are considered. RESULTS: The proposed methods were applied to data from a bladder cancer clinical trial to determine whether the neutrophil-to-lymphocyte ratio (NLR) is a valuable biomarker for predicting overall survival following surgery or combined chemotherapy and surgery. The TD-LR method yielded results consistent with the original findings while providing an easily interpretable three-dimensional surface display of how NLR related to the likelihood of event in the trial data. CONCLUSIONS: The TD-LR provides a more nuanced understanding of the relationship between continuous markers and the likelihood of events in censored survival data. This method also allows more straightforward communication with a clinical audience through graphical presentation.

A phase I trial of pembrolizumab with hypofractionated radiotherapy in patients with metastatic solid tumours.

BACKGROUND: We conducted a phase I trial evaluating pembrolizumab+hypofractionated radiotherapy (HFRT) for patients with metastatic cancers. METHODS: There were two strata (12 patients each): (i) NSCLC/melanoma progressing on prior anti-PD-1 therapy, (ii) other cancer types; anti-PD-1-naive. Patients received 6 cycles of pembrolizumab, starting 1 week before HFRT. Patients had ≥2 lesions; only one was irradiated (8 Gy × 3 for first half; 17 Gy × 1 for second half in each stratum) and the other(s) followed for response. RESULTS: Of the 24 patients, 20 (83%) had treatment-related adverse events (AEs) (all grade 1 or 2). There were eight grade 3 AEs, none treatment related. There were no dose-limiting toxicities or grade 4/5 AEs. Stratum 1: two patients (of 12) with progression on prior PD-1 blockade experienced prolonged responses (9.2 and 28.1 months). Stratum 2: one patient experienced a complete response and two had prolonged stable disease (7.4 and 7.0 months). Immune profiling demonstrated that anti-PD-1 therapy and radiation induced a consistent increase in the proliferation marker Ki67 in PD-1-expressing CD8 T cells. CONCLUSIONS: HFRT was well tolerated with pembrolizumab, and in some patients with metastatic NSCLC or melanoma, it reinvigorated a systemic response despite previous progression on anti-PD-1 therapy. CLINICAL TRIAL REGISTRATION: NCT02303990 ( www.clinicaltrials.gov ).

Initial report of the genitourinary and gastrointestinal toxicity of post-prostatectomy proton therapy for prostate cancer patients undergoing adjuvant or salvage radiotherapy.

PURPOSE: To report acute and late genitourinary (GU) and gastrointestinal (GI) toxicities associated with post-prostatectomy proton therapy (PT). METHODS: The first 100 consecutive patients from 2010 to 2016 were retrospectively assessed. Baseline characteristics, prospectively graded CTCAE v4.0 toxicities, and patient-reported outcomes were reported. Late outcomes were reported for 79 patients with 3 months minimum follow up. Toxicity-free survival Kaplan-Meier curves were estimated. Logistic regression assessed associations between toxicities and clinical and treatment characteristics (p < .05 significance). RESULTS: Median age, months after surgery, and months of follow-up were respectively 64 years (range 42-77), 25 (5-216), and 25 (0-47). PT received was 70.2 Gy (RBE) (89%), salvage (93%), prostate bed only (80%), pencil beam scanning (86%), with IMRT (31%), and with androgen deprivation (34%). Acute and late maximum toxicities, respectively were: GU grade 0 (14%; 18%), 1 (71%; 62%), 2 (15%; 20%), ≥3 (0), and GI: grade 0 (66%; 73%), 1 (34%; 27%), ≥2 (0). Toxicity-free survival at 24 months was GU grade 2 (83%) and GI grade 1 (74%). Mean (±std dev) baseline International Prostate Symptom Score (IPSS), International Index of Erectile Function, and Expanded Prostate Cancer Index Composite bowel function and bother were 6.6 ± 6.1, 10.5 ± 7.3, 90.9 ± 10.8, 93.3 ± 11.2, respectively, and largely unchanged at 2 years: 6.3 ± 3.6, 11.1 ± 6.3, 92.8 ± 5.8, and 90.9 ± 10.3. On multivariate analysis, baseline IPSS (p = .009) associated with GU grade 2 acute toxicity. Bladderless-CTV median dose, V30, and V40 associated with GU grade 2 acute toxicity and maximum dose with late (Ps <0.05). For GI, on multivariate analysis, baseline bowel function (p = .033) associated with acute grade 1 toxicity. Rectal minimum and median dose, V10, and V20, and anterior rectal wall median dose and V10 through V65 associated with acute grade 1 GI toxicity (Ps < .05). CONCLUSIONS: Post-prostatectomy PT for prostate cancer is feasible with a favorable GU and GI toxicity profile acutely and through early follow up.

Neutrophil-to-lymphocyte ratio as a bladder cancer biomarker: Assessing prognostic and predictive value in SWOG 8710.

BACKGROUND: Risk stratification is a major challenge in bladder cancer (BC), and a biomarker is needed. Multiple studies have reported the neutrophil-to-lymphocyte ratio (NLR) as a promising candidate; however, these analyses have methodological limitations. Therefore, the authors performed a category B biomarker study to test whether NLR is prognostic for overall survival (OS) after curative treatment or is predictive for the survival benefit from neoadjuvant chemotherapy (NAC). METHODS: This study is an unplanned secondary analysis of SWOG 8710, a randomized phase 3 trial that assessed cystectomy with or without NAC in 317 patients with muscle-invasive BC. NLR was calculated from prospectively collected complete blood counts. For the prognostic analysis, 230 patients were identified; for the predictive analysis, 263 were identified. NLR was evaluated with proportional hazards models including prespecified factors (age, sex, T-stage, lymphovascular invasion, and treatment arm). RESULTS: With a median follow-up of 18.6 years, there were 172 and 205 deaths in the prognostic and predictive cohorts, respectively. In a multivariable analysis, NLR was not prognostic for OS (hazard ratio [HR], 1.04; 95% confidence interval [CI], 0.98-1.11; P = .24). Furthermore, NLR did not predict for the OS benefit from NAC (HR, 1.01; 95% CI, 0.90-1.14; P = .86). Factors associated with worse OS were older age (HR, 1.05; 95% CI, 1.04-1.07; P < .001) and surgery without NAC (HR, 1.39; 95% CI, 1.03-1.88; P = .03). CONCLUSIONS: This is the first analysis of NLR in BC to use prospectively collected clinical trial data. In contrast to previous studies, it suggests that NLR is neither a prognostic nor predictive biomarker for OS in muscle-invasive BC. Cancer 2017;123:794-801. © 2016 American Cancer Society.

A case-matched study of toxicity outcomes after proton therapy and intensity-modulated radiation therapy for prostate cancer.

BACKGROUND: The authors assessed whether proton beam therapy (PBT) for prostate cancer (PCa) was associated with differing toxicity compared with intensity-modulated radiation therapy (IMRT) using case-matched analysis. METHODS: From 2010 to 2012, 394 patients who had localized PCa received 79.2 Gray (Gy) relative biologic effectiveness (RBE) delivered with either PBT (181 patients) or IMRT (213 patients). Patients were case-matched on risk group, age, and prior gastrointestinal (GI) and genitourinary (GU) disorders, resulting in 94 matched pairs. Both exact matching (risk group) and nearest-neighbor matching (age, prior GI/GU disorders) were used. Residual confounding was adjusted for by using multivariable regression. Maximum acute and late GI/GU Common Terminology Criteria for Adverse Events-graded toxicities were compared using univariate and multivariable logistic and Cox regression models, respectively. RESULTS: Bladder and rectum dosimetry variables were significantly lower for PBT versus IMRT (P ≤ .01). The median follow-up was 47 months (range, 5-65 months) for patients who received IMRT and 29 months (range, 5-50 months) for those who received PBT. On multivariable analysis, which exploited case matching and included direct adjustment for confounders and independent predictors, there were no statistically significant differences between IMRT and PBT in the risk of grade ≥ 2 acute GI toxicity (odds ratio, 0.27; 95% confidence interval [CI], 0.06-1.24; P = .09), grade ≥ 2 acute GU toxicity (odds ratio, 0.69; 95% CI, 0.32-1.51; P = .36), grade ≥ 2 late GU toxicity (hazard ratio, 0.56; 95% CI, 0.22-1.41; P = .22), and grade ≥ 2 late GI toxicity (hazard ratio, 1.24; 95% CI, 0.53-2.94; P = .62). CONCLUSIONS: In this matched comparison of prospectively collected toxicity data on patients with PCa who received treatment with contemporary IMRT and PBT techniques and similar dose-fractionation schedules, the risks of acute and late GI/GU toxicities did not differ significantly after adjustment for confounders and predictive factors.

Optimizing bladder cancer locoregional failure risk stratification after radical cystectomy using SWOG 8710.

BACKGROUND: Clinical trials of radiation after radical cystectomy (RC) and chemotherapy for bladder cancer are in development, but inclusion and stratification factors have not been clearly established. In this study, the authors evaluated and refined a published risk stratification for locoregional failure (LF) by applying it to a multicenter patient cohort. METHODS: The original stratification, which was developed using a single-institution series, produced 3 subgroups with significantly different LF risk based on pathologic tumor (pT) classification and the number of lymph nodes identified. This model was then applied to patients in Southwest Oncology Group (SWOG) 8710, a randomized trial of RC with or without chemotherapy. LF was defined as any pelvic failure before or within 3 months of distant failure. RESULTS: Patients in the development cohort and the SWOG cohort had significantly different baseline characteristics. The original risk model was not fully validated in the SWOG cohort, because lymph node yield was not as strongly associated with LF as in the development cohort. Regression analysis indicated that margin status could improve the model. A revised stratification using pT classification, margin status, and the number of lymph nodes identified produced 3 subgroups with significantly different LF risk in both cohorts: low risk (≤pT2), intermediate risk (≥pT3 with negative margins AND ≥10 lymph nodes identified), and high risk (≥pT3 with positive margins OR <10 lymph nodes identified) with 5-year LF rates of 8%, 20%, and 41%, respectively, in the SWOG cohort and 8%, 19%, and 41%, respectively, in the development cohort. CONCLUSIONS: A model incorporating pT classification, margin status, and the number of lymph nodes identified stratified LF risk in 2 different RC populations and may inform the design of future trials.

The Radiation Therapy Technology Evidence Matrix: a framework to visualize evidence development for innovations in radiation therapy.

Clinical evidence is crucial in enabling the judicious adoption of technological innovations in radiation therapy (RT). Pharmaceutical evidence development frameworks are not useful for understanding how technical advances are maturing. In this paper, we introduce a new framework, the Radiation Therapy Technology Evidence Matrix (rtTEM), that helps visualize how the clinical evidence supporting new technologies is developing. The matrix is a unique 2D model based on the R-IDEAL clinical evaluation framework. It can be applied to clinical hypothesis testing trials, as well as publications reporting clinical treatment. We present the rtTEM and illustrate its application, using emerging and mature RT technologies as examples. The model breaks down the type of claim along the vertical axis and the strength of the evidence for that claim on the horizontal axis, both of which are inherent in clinical hypothesis testing. This simplified view allows for stakeholders to understand where the evidence is and where it is heading. Ultimately, the value of an innovation is typically demonstrated through superiority studies, which we have divided into three key categories - administrative, toxicity and control, to enable more detailed visibility of evidence development in that claim area. We propose the rtTEM can be used to track evidence development for new interventions in RT. We believe it will enable researchers and sponsors to identify gaps in evidence and to further direct evidence development. Thus, by highlighting evidence looked for by key policy decision makers, the rtTEM will support wider, timely patient access to high value technological advances.

Dataset of weekly intra-treatment diffusion weighted imaging in head and neck cancer patients treated with MR-Linac.

Radiation therapy (RT) is a crucial treatment for head and neck squamous cell carcinoma (HNSCC); however, it can have adverse effects on patients' long-term function and quality of life. Biomarkers that can predict tumor response to RT are being explored to personalize treatment and improve outcomes. While tissue and blood biomarkers have limitations, imaging biomarkers derived from magnetic resonance imaging (MRI) offer detailed information. The integration of MRI and a linear accelerator in the MR-Linac system allows for MR-guided radiation therapy (MRgRT), offering precise visualization and treatment delivery. This data descriptor offers a valuable repository for weekly intra-treatment diffusion-weighted imaging (DWI) data obtained from head and neck cancer patients. By analyzing the sequential DWI changes and their correlation with treatment response, as well as oncological and survival outcomes, the study provides valuable insights into the clinical implications of DWI in HNSCC.

Prostate Cancer Recurrence: Examining the Role of Salvage Radiotherapy Field and Risk Factors for Regional Disease Recurrence Captured on 18F-DCFPyL PET/CT.

PURPOSE: The role of elective pelvic nodal irradiation in salvage radiotherapy (sRT) remains controversial. Utilizing 18F-DCFPyL PET/CT, this study aimed to investigate differences in disease distribution after whole pelvic (WPRT) or prostate bed (PBRT) radiotherapy and to identify risk factors for pelvic lymph node (LN) relapse. METHODS: This retrospective study included patients with PSA > 0.1 ng/mL post-radical prostatectomy (RP) or post-RP and sRT who underwent 18F-DCFPyL PET/CT. Disease distribution on 18F-DCFPyL PET/CT after sRT was compared using Chi-square tests. Risk factors were tested for association with pelvic LN relapse after RP and salvage PBRT using logistic regression. RESULTS: 979 18F-DCFPyL PET/CTs performed at our institution between 1/1/2022 - 3/24/2023 were analyzed. There were 246 patients meeting criteria, of which 84 received salvage RT after RP (post-salvage RT group) and 162 received only RP (post-RP group). Salvage PBRT patients (n = 58) had frequent pelvic nodal (53.6%) and nodal-only (42.6%) relapse. Salvage WPRT patients (n = 26) had comparatively lower rates of pelvic nodal (16.7%, p = 0.002) and nodal-only (19.2%, p = 0.04) relapse. The proportion of distant metastases did not differ between the two groups. Multiple patient characteristics, including ISUP grade and seminal vesicle invasion, were associated with pelvic LN disease in the post-RP group. CONCLUSION: At PSA persistence or progression, salvage WPRT resulted in lower rates of nodal involvement than salvage PBRT, but did not reduce distant metastases. Certain risk factors increase the likelihood of pelvic LN relapse after RP and can help inform salvage RT field selection.

Investigation of autosegmentation techniques on T2-weighted MRI for off-line dose reconstruction in MR-linac workflow for head and neck cancers.

BACKGROUND: In order to accurately accumulate delivered dose for head and neck cancer patients treated with the Adapt to Position workflow on the 1.5T magnetic resonance imaging (MRI)-linear accelerator (MR-linac), the low-resolution T2-weighted MRIs used for daily setup must be segmented to enable reconstruction of the delivered dose at each fraction. PURPOSE: In this pilot study, we evaluate various autosegmentation methods for head and neck organs at risk (OARs) on on-board setup MRIs from the MR-linac for off-line reconstruction of delivered dose. METHODS: Seven OARs (parotid glands, submandibular glands, mandible, spinal cord, and brainstem) were contoured on 43 images by seven observers each. Ground truth contours were generated using a simultaneous truth and performance level estimation (STAPLE) algorithm. Twenty total autosegmentation methods were evaluated in ADMIRE: 1-9) atlas-based autosegmentation using a population atlas library (PAL) of 5/10/15 patients with STAPLE, patch fusion (PF), random forest (RF) for label fusion; 10-19) autosegmentation using images from a patient's 1-4 prior fractions (individualized patient prior [IPP]) using STAPLE/PF/RF; 20) deep learning (DL) (3D ResUNet trained on 43 ground truth structure sets plus 45 contoured by one observer). Execution time was measured for each method. Autosegmented structures were compared to ground truth structures using the Dice similarity coefficient, mean surface distance (MSD), Hausdorff distance (HD), and Jaccard index (JI). For each metric and OAR, performance was compared to the inter-observer variability using Dunn's test with control. Methods were compared pairwise using the Steel-Dwass test for each metric pooled across all OARs. Further dosimetric analysis was performed on three high-performing autosegmentation methods (DL, IPP with RF and 4 fractions [IPP_RF_4], IPP with 1 fraction [IPP_1]), and one low-performing (PAL with STAPLE and 5 atlases [PAL_ST_5]). For five patients, delivered doses from clinical plans were recalculated on setup images with ground truth and autosegmented structure sets. Differences in maximum and mean dose to each structure between the ground truth and autosegmented structures were calculated and correlated with geometric metrics. RESULTS: DL and IPP methods performed best overall, all significantly outperforming inter-observer variability and with no significant difference between methods in pairwise comparison. PAL methods performed worst overall; most were not significantly different from the inter-observer variability or from each other. DL was the fastest method (33 s per case) and PAL methods the slowest (3.7-13.8 min per case). Execution time increased with a number of prior fractions/atlases for IPP and PAL. For DL, IPP_1, and IPP_RF_4, the majority (95%) of dose differences were within ± 250 cGy from ground truth, but outlier differences up to 785 cGy occurred. Dose differences were much higher for PAL_ST_5, with outlier differences up to 1920 cGy. Dose differences showed weak but significant correlations with all geometric metrics (R2 between 0.030 and 0.314). CONCLUSIONS: The autosegmentation methods offering the best combination of performance and execution time are DL and IPP_1. Dose reconstruction on on-board T2-weighted MRIs is feasible with autosegmented structures with minimal dosimetric variation from ground truth, but contours should be visually inspected prior to dose reconstruction in an end-to-end dose accumulation workflow.

Setting the Stage: Feasibility and Baseline Characteristics in the PARTIQoL Trial Comparing Proton Therapy Versus Intensity Modulated Radiation Therapy for Localized Prostate Cancer.

PURPOSE: Men with localized prostate cancer may receive either photon-based intensity modulated radiation therapy (IMRT) or proton beam therapy (PBT). The PARTIQoL trial (NCT01617161) demonstrates the feasibility of performing a large, multicenter phase 3 randomized trial comparing IMRT with PBT for localized prostate cancer. Here, we report baseline features of patients enrolled on this trial and present strategies to improve feasibility of other similar trials. METHODS AND MATERIALS: Patients with low- or intermediate-risk prostate cancer were randomly assigned to either PBT or IMRT with stratification by institution, age, use of rectal spacer, and fractionation schedule (conventional fractionation: 79.2 Gy in 44 fractions vs moderate hypofractionation: 70.0 Gy in 28 fractions). The primary endpoint is a change from baseline bowel health using the Expanded Prostate Index Composite score 24 months after radiation therapy. Secondary objectives include treatment-related differences in urinary and erectile functions, adverse events, and efficacy endpoints. RESULTS: Between July 2012 and November 2021, 450 patients were successfully accrued. Patients were randomly assigned to either PBT (N = 226) or to IMRT (N = 224); 13 were ineligible or withdrew before treatment. The median age of 437 analyzed patients was 68 years (range, 46-89 years). A total of 41% of patients had low-risk and 59% had intermediate-risk disease. In total, 49% of patients were treated with conventional fractionation and 51% with moderately hypofractionation. 48% of patients used a rectal spacer. For patients receiving PBT, pencil beam scanning was used in 48%. PBT and IMRT arms were balanced for baseline variables. CONCLUSIONS: Despite significant challenges, the PARTIQoL trial demonstrated that, with targeted recruitment approaches, multicenter collaboration, payer engagement, and protocol updates to incorporate contemporary techniques, it is feasible to perform a large phase 3 randomized clinical trial to assess whether PBT improves outcomes. We will separately report primary results and continue to monitor participants for longer follow-up and secondary endpoints.

Associations Between Radiation Oncologist Demographic Factors and Segmentation Similarity Benchmarks: Insights From a Crowd-Sourced Challenge Using Bayesian Estimation.

PURPOSE: The quality of radiotherapy auto-segmentation training data, primarily derived from clinician observers, is of utmost importance. However, the factors influencing the quality of clinician-derived segmentations are poorly understood; our study aims to quantify these factors. METHODS: Organ at risk (OAR) and tumor-related segmentations provided by radiation oncologists from the Contouring Collaborative for Consensus in Radiation Oncology data set were used. Segmentations were derived from five disease sites: breast, sarcoma, head and neck (H&N), gynecologic (GYN), and GI. Segmentation quality was determined on a structure-by-structure basis by comparing the observer segmentations with an expert-derived consensus, which served as a reference standard benchmark. The Dice similarity coefficient (DSC) was primarily used as a metric for the comparisons. DSC was stratified into binary groups on the basis of structure-specific expert-derived interobserver variability (IOV) cutoffs. Generalized linear mixed-effects models using Bayesian estimation were used to investigate the association between demographic variables and the binarized DSC for each disease site. Variables with a highest density interval excluding zero were considered to substantially affect the outcome measure. RESULTS: Five hundred seventy-four, 110, 452, 112, and 48 segmentations were used for the breast, sarcoma, H&N, GYN, and GI cases, respectively. The median percentage of segmentations that crossed the expert DSC IOV cutoff when stratified by structure type was 55% and 31% for OARs and tumors, respectively. Regression analysis revealed that the structure being tumor-related had a substantial negative impact on binarized DSC for the breast, sarcoma, H&N, and GI cases. There were no recurring relationships between segmentation quality and demographic variables across the cases, with most variables demonstrating large standard deviations. CONCLUSION: Our study highlights substantial uncertainty surrounding conventionally presumed factors influencing segmentation quality relative to benchmarks.

Safety and Tolerability of Online Adaptive High-Field Magnetic Resonance-Guided Radiotherapy.

Importance: In 2018, the first online adaptive magnetic resonance (MR)-guided radiotherapy (MRgRT) system using a 1.5-T MR-equipped linear accelerator (1.5-T MR-Linac) was clinically introduced. This system enables online adaptive radiotherapy, in which the radiation plan is adapted to size and shape changes of targets at each treatment session based on daily MR-visualized anatomy. Objective: To evaluate safety, tolerability, and technical feasibility of treatment with a 1.5-T MR-Linac, specifically focusing on the subset of patients treated with an online adaptive strategy (ie, the adapt-to-shape [ATS] approach). Design, Setting, and Participants: This cohort study included adults with solid tumors treated with a 1.5-T MR-Linac enrolled in Multi Outcome Evaluation for Radiation Therapy Using the MR-Linac (MOMENTUM), a large prospective international study of MRgRT between February 2019 and October 2021. Included were adults with solid tumors treated with a 1.5-T MR-Linac. Data were collected in Canada, Denmark, The Netherlands, United Kingdom, and the US. Data were analyzed in August 2023. Exposure: All patients underwent MRgRT using a 1.5-T MR-Linac. Radiation prescriptions were consistent with institutional standards of care. Main Outcomes and Measures: Patterns of care, tolerability, and technical feasibility (ie, treatment completed as planned). Acute high-grade radiotherapy-related toxic effects (ie, grade 3 or higher toxic effects according to Common Terminology Criteria for Adverse Events version 5.0) occurring within the first 3 months after treatment delivery. Results: In total, 1793 treatment courses (1772 patients) were included (median patient age, 69 years [range, 22-91 years]; 1384 male [77.2%]). Among 41 different treatment sites, common sites were prostate (745 [41.6%]), metastatic lymph nodes (233 [13.0%]), and brain (189 [10.5%]). ATS was used in 1050 courses (58.6%). MRgRT was completed as planned in 1720 treatment courses (95.9%). Patient withdrawal caused 5 patients (0.3%) to discontinue treatment. The incidence of radiotherapy-related grade 3 toxic effects was 1.4% (95% CI, 0.9%-2.0%) in the entire cohort and 0.4% (95% CI, 0.1%-1.0%) in the subset of patients treated with ATS. There were no radiotherapy-related grade 4 or 5 toxic effects. Conclusions and Relevance: In this cohort study of patients treated on a 1.5-T MR-Linac, radiotherapy was safe and well tolerated. Online adaptation of the radiation plan at each treatment session to account for anatomic variations was associated with a low risk of acute grade 3 toxic effects.

Bladder preservation in the treatment of muscle-invasive bladder cancer (MIBC): a review of the literature and a practical approach to therapy.

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Bladder preservation therapies for muscle-invasive bladder cancer (MIBC) have been developed to address the needs of two cohorts: patients with severe medical co-morbidities for whom radical cystectomy is too high risk and patients with limited disease who wish to avoid aggressive surgery. There are multiple bladder preservation options, although the trimodal approach of maximal transurethral resection with chemoradiotherapy is the most strongly supported. While outcomes are worse for patients unfit for surgery than those otherwise fit for surgery, bladder preservation approaches still offer curative potential. We present a comprehensive review of the literature and outline a practical approach to bladder preservation therapy for MIBC. This review aims to help urologists easily navigate through the decision tree of therapeutic options. Radical cystectomy (RC) is associated with considerable morbidity. Aside from the perioperative period, RC with urinary diversion poses great potential for long-term complications and morbidity. Bladder preservation therapies for muscle-invasive bladder cancer (MIBC) have been developed to address the needs of two cohorts: patients with severe medical co-morbidities for whom a radical surgery is too high risk and patients with limited disease who wish to avoid radical surgery. The goal of achieving complete response to treatment while maintaining bladder form and function has led to the development of multimodal approaches to this disease. There are multiple bladder preservation options, although the trimodal approach of maximal transurethral resection with chemoradiotherapy is the most strongly supported. In medically operable patients ('fit' for surgery), there is abundant evidence to support trimodal therapy as an acceptable treatment option for highly selected patients with MIBC with favourable pathological parameters. While outcomes are worse for medically inoperable patients ('unfit' for surgery), bladder preservation approaches still offer curative potential. However, prospective trials comparing the above regimens to RC are still needed to better define their role in the treatment of MIBC. We present a comprehensive review of the literature and outline a practical approach to bladder preservation therapy for MIBC.

Radical cystectomy versus bladder-preserving therapy for muscle-invasive urothelial carcinoma: examining confounding and misclassification biasin cancer observational comparative effectiveness research.

OBJECTIVES: Radical cystectomy (RC) is the standard treatment for muscle-invasive urothelial carcinoma of the bladder. Trimodality bladder-preserving therapy (BPT) is an alternative to RC, but randomized comparisons of RC versus BPT have proven infeasible. To compare RC versus BPT, we undertook an observational cohort study using registry and administrative claims data from the Surveillance, Epidemiology and End Results-Medicare database. METHODS: We identified patients age 65 years or older diagnosed between 1995 and 2005 who received RC (n = 1426) or BPT (n = 417). We examined confounding and stage misclassification in the comparison of RC and BPT by using multivariable adjustment, propensity score-based adjustment, instrumental variable (IV) analysis, and simulations. RESULTS: Patients who received BPT were older and more likely to have comorbid disease. After propensity score adjustment, BPT was associated with an increased hazard of death from any cause (hazard ratio [HR] 1.26; 95% confidence interval [CI] 1.05-1.53) and from bladder cancer (HR 1.31; 95% CI 0.97-1.77). Using the local area cystectomy rate as an instrument, IV analysis demonstrated no differences in survival between BPT and RC (death from any cause HR 1.06; 95% CI 0.78-1.31; death from bladder cancer HR 0.94; 95% CI 0.55-1.18). Simulation studies for stage misclassification yielded results consistent with the IV analysis. CONCLUSIONS: Survival estimates in an observational cohort of patients who underwent RC versus BPT differ by analytic method. Multivariable and propensity score adjustment revealed greater mortality associated with BPT relative to RC, while IV analysis and simulation studies suggest that the two treatments are associated with similar survival outcomes.

Cancer Control, Toxicity, and Secondary Malignancy Risks of Proton Radiation Therapy for Stage I-IIB Testicular Seminoma.

Purpose: This study's objective was to report cancer control and toxicity outcomes after proton radiation therapy (RT) in testicular seminoma and to compare secondary malignancy (SMN) risks with photon-based treatment alternatives. Methods and Materials: Consecutive patients with stage I-IIB testicular seminoma treated with proton RT at a single institution were retrospectively analyzed. Kaplan-Meier estimates for disease-free and overall survival were computed. Toxicities were scored using Common Terminology Criteria for Adverse Events version 5.0. Photon comparison plans, including 3-dimensional conformal RT (3D-CRT) and intensity modulated RT (IMRT)/volumetric arc therapy (VMAT), were created for each patient. Dosimetric parameters and SMN risk predictions for different in-field organs-at-risk were compared between the techniques. Excess absolute SMN risks were estimated with organ equivalent dose modeling. Results: Twenty-four patients were included (median age, 38.5 years). The majority of patients had stage II disease (IIA, 12 [50.0%]; IIB, 11 [45.8%]; IA, 1 [4.2%]). Seven (29.2%) and 17 (70.8%) patients had de novo and recurrent disease, respectively (de novo/recurrent: IA, 1/0; IIA, 4/8; IIB, 2/9). Most acute toxicities were mild (grade 1 [G1], 79.2%; G2, 12.5%) with G1 nausea being most common (70.8%). No serious events (G3-5) occurred. With a median follow-up time of 3 years (interquartile range, 2.1-3.6 years), 3-year disease-free and overall survival rates were 90.9% (95% confidence interval, 68.1%-97.6%) and 100% (95% confidence interval, 100%-100%), respectively. There were no documented late toxicities in the follow-up period, including worsening serial creatinine levels suggestive of early nephrotoxicity. Proton RT had significant reductions in mean organ-at-risk doses to the kidneys, stomach, colon, liver, bladder, and body compared with both 3D-CRT and IMRT/VMAT. Proton RT had significantly lower SMN risk predictions compared with 3D-CRT and IMRT/VMAT. Conclusions: Cancer control and toxicity outcomes using proton RT in stage I-IIB testicular seminoma are consistent with existing photon-based RT literature. However, proton RT may be associated with significantly lower SMN risks.