Evaluation of knowledge-based planning models for male pelvic CBCT-based online adaptive radiotherapy on conventional linear accelerators.

PURPOSE: To assess the practicality of employing a commercial knowledge-based planning tool (RapidPlan) to generate adapted intact prostate and prostate bed volumetric modulated arc therapy (VMAT) plans on iterative cone-beam computed tomography (iCBCT) datasets. METHODS AND MATERIALS: Intact prostate and prostate bed RapidPlan models were trained utilizing planning data from 50 and 44 clinical cases, respectively. To ensure that refined models were capable of producing adequate clinical plans with a single optimization, models were tested with 50 clinical planning CT datasets by comparing dose-volume histogram (DVH) and plan quality metric (PQM) values between clinical and RapidPlan-generated plans. The RapidPlan tool was then used to retrospectively generate adapted VMAT plans on daily iCBCT images for 20 intact prostate and 15 prostate bed cases. As before, DVH and PQM metrics were utilized to dosimetrically compare scheduled (iCBCT Verify) and adapted (iCBCT RapidPlan) plans. Timing data was collected to further evaluate the feasibility of integrating this approach within an online adaptive radiotherapy workflow. RESULTS: Model testing results confirmed the models were capable of producing VMAT plans within a single optimization that were overall improved upon or dosimetrically comparable to original clinical plans. Direct application of RapidPlan on iCBCT datasets produced satisfactory intact prostate and prostate bed plans with generally improved target volume coverage/conformality and rectal sparing relative to iCBCT Verify plans as indicated by DVH values, though bladder metrics were marginally increased on average. Average PQM values for iCBCT RapidPlans were significantly improved compared to iCBCT Verify plans. The average time required [in mm:ss] to generate adapted plans was 06:09 ± 02:06 (intact) and 07:12 ± 01:04 (bed). CONCLUSION: This study demonstrated the feasibility of leveraging RapidPlan to expeditiously generate adapted VMAT intact prostate and prostate bed plans on iCBCT datasets. In general, adapted plans were dosimetrically improved relative to scheduled plans, emphasizing the practicality of the proposed approach.

Conventional versus hypofractionated postmastectomy proton radiotherapy in the USA (MC1631): a randomised phase 2 trial.

BACKGROUND: Proton therapy is under investigation in breast cancer as a strategy to reduce radiation exposure to the heart and lungs. So far, studies investigating proton postmastectomy radiotherapy (PMRT) have used conventional fractionation over 25-28 days, but whether hypofractionated proton PMRT is feasible is unclear. We aimed to compare conventional fractionation and hypofractionation in patients with indications for PMRT, including those with immediate breast reconstruction. METHODS: We did a randomised phase 2 trial (MC1631) at Mayo Clinic in Rochester (MN, USA) and Mayo Clinic in Arizona (Phoenix, AZ, USA) comparing conventional fractionated (50 Gy in 25 fractions of 2 Gy [relative biological effectiveness of 1·1]) and hypofractionated (40·05 Gy in 15 fractions of 2·67 Gy [relative biological effectiveness of 1·1]) proton PMRT. All patients were treated with pencil-beam scanning. Eligibility criteria included age 18 years or older, an Eastern Cooperative Oncology Group performance status of 0-2, and breast cancer resected by mastectomy with or without immediate reconstruction with indications for PMRT. Patients were randomly assigned (1:1) to either conventional fractionation or hypofractionation, with presence of immediate reconstruction (yes vs no) as a stratification factor, using a biased-coin minimisation algorithm. Any patient who received at least one fraction of protocol treatment was evaluable for the primary endpoint and safety analyses. The primary endpoint was 24-month complication rate from the date of first radiotherapy, defined as grade 3 or worse adverse events occurring from 90 days after last radiotherapy or unplanned surgical interventions in patients with immediate reconstruction. The inferiority of hypofractionation would not be ruled out if the upper bound of the one-sided 95% CI for the difference in 24-month complication rate between the two groups was greater than 10%. This trial is registered with ClinicalTrials.gov, NCT02783690, and is closed to accrual. FINDINGS: Between June 2, 2016, and Aug 23, 2018, 88 patients were randomly assigned (44 to each group), of whom 82 received protocol treatment (41 in the conventional fractionation group and 41 in the hypofractionation group; median age of 52 years [IQR 44-64], 79 [96%] patients were White, two [2%] were Black or African American, one [1%] was Asian, and 79 [96%] were not of Hispanic ethnicity). As of data cutoff (Jan 30, 2023), the median follow-up was 39·3 months (IQR 37·5-61·2). The median mean heart dose was 0·54 Gy (IQR 0·30-0·72) for the conventional fractionation group and 0·49 Gy (0·25-0·64) for the hypofractionation group. Within 24 months of first radiotherapy, 14 protocol-defined complications occurred in six (15%) patients in the conventional fractionation group and in eight (20%) patients in the hypofractionation group (absolute difference 4·9% [one-sided 95% CI 18·5], p=0·27). The complications in the conventionally fractionated group were contracture (five [12%] of 41 patients]) and fat necrosis (one [2%] patient) requiring surgical intervention. All eight protocol-defined complications in the hypofractionation group were due to infections, three of which were acute infections that required surgical intervention, and five were late infections, four of which required surgical intervention. All 14 complications were in patients with immediate expander or implant-based reconstruction. INTERPRETATION: After a median follow-up of 39·3 months, non-inferiority of the hypofractionation group could not be established. However, given similar tolerability, hypofractionated proton PMRT appears to be worthy of further study in patients with and without immediate reconstruction. FUNDING: The Department of Radiation Oncology, Mayo Clinic, Rochester, MN, the Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, USA, and the US National Cancer Institute.

A Phase II prospective study of hypofractionated proton therapy of prostate and pelvic lymph nodes: Acute effects on patient-reported quality of life.

BACKGROUND: The objective of this study was to report acute changes in patient-reported quality of life (PRQOL) using the 26-item Expanded Prostate Index Composite (EPIC-26) questionnaire in a prospective study using hypofractionated intensity-modulated proton beam therapy (H-IMPT) targeting the prostate and the pelvic lymph nodes for high-risk or unfavorable intermediate-risk prostate cancer. METHODS: Fifty-five patients were enrolled. H-IMPT consisted of 45 GyE to the pelvic lymph nodes and 67.5 GyE to the prostate and seminal vesicles in 25 fractions. PRQOL was assessed with the urinary incontinence (UI), urinary irritative/obstructive symptoms (UO), and bowel function (BF) domains of EPIC-26 questionnaire. Mean changes in domain scores were analyzed from pretreatment to the end of treatment and 3 months posttreatment. A clinically meaningful change (or minimum important change) was defined as a score change > 50% of the baseline standard deviation. RESULTS: The mean scores of UO, UI, and BF at baseline were 84.6, 91.1, and 95.3, respectively. At the end of treatment, there were statistically significant and clinically meaningful declines in UO and BF scores (-13.5 and -2.3, respectively), while the decline in UI score was statistically significant but not clinically meaningful (-13.7). A clinically meaningful decline in UO, UI, and BF scores occurred in 53.5%, 22.7%, and 73.2% of the patients, respectively. At 3 months posttreatment, all three mean scores showed an improvement, with fewer patients having a clinically meaningful decline in UO, UI, and BF scores (18.4%, 20.5%, and 45.0%, respectively). There was no significant reduction in the mean UO and UI scores compared to baseline, although the mean BF score remained lower than baseline and the difference was clinically meaningful. CONCLUSIONS: UO, UI, and BF scores of PRQOL declined at the end of H-IMPT. UO and UI scores showed improvement at 3 months posttreatment and were similar to the baseline scores. However, BF score remained lower at 3 months posttreatment with a clinically meaningful decline.

Cost effectiveness of treatment strategies for high risk prostate cancer.

BACKGROUND: Patients with high-risk prostate cancer (HRPC) have multiple accepted treatment options. Because there is no overall survival benefit of one option over another, appropriate treatment must consider patient life expectancy, quality of life, and cost. METHODS: The authors compared quality-adjusted life years (QALYs) and cost effectiveness among treatment options for HRPC using a Markov model with three treatment arms: (1) external-beam radiotherapy (EBRT) delivered with 20 fractions, (2) EBRT with 23 fractions followed by low-dose-rate (LDR) brachytherapy boost, or (3) radical prostatectomy alone. An exploratory analysis considered a simultaneous integrated boost according to the FLAME trial (ClinicalTrials.gov identifier NCT01168479). RESULTS: Treatment strategies were compared using the incremental cost-effectiveness ratio (ICER). EBRT with LDR brachytherapy boost was a cost-effective strategy (ICER, $20,929 per QALY gained). These results were most sensitive to variations in the biochemical failure rate. However, the results still demonstrated cost effectiveness for the brachytherapy boost paradigm, regardless of any tested parameter ranges. Probabilistic sensitivity analysis demonstrated that EBRT with LDR brachytherapy was favored in 52% of 100,000 Monte Carlo iterations. In an exploratory analysis, EBRT with a simultaneous integrated boost was also a cost-effective strategy, resulting in an ICER of $62,607 per QALY gained; however, it was not cost effective compared with EBRT plus LDR brachytherapy boost. CONCLUSIONS: EBRT with LDR brachytherapy boost may be a cost-effective treatment strategy compared with EBRT alone and radical prostatectomy for HRPC, demonstrating high-value care. The current analysis suggests that a reduction in biochemical failure alone can result in cost-effective care, despite no change in overall survival.

Utilizing open-source platforms to build and deploy interactive patient-reported quality of life tracking tools for monitoring protocol adherence.

PURPOSE: Tracking patient-reported outcomes (PROs) and quality-of-life response rates is essential for clinical trials. Historically, rates are monitored through scheduled reports, which can require gathering, merging, and cleaning data from multiple databases. At the end of this process, if gaps are found, new data are entered and the cycle repeats, leaving a trail of reports that are not up-to-date or immediately accessible to the investigator. The financial and person-hour cost of utilizing clinical research staff for this purpose is impractical. Online dashboards are continuously updated to monitor data, providing on-demand access to promote successful research. METHODS: Dashboard implementation utilizes R, an open-source statistical programming language, RMarkdown, a markup language, Flexdashboard, which creates structural elements, and Shiny, allowing investigators the ability to interact with data within the dashboard. By leveraging these four elements, powerful, cost-effective interactive dashboards can be built. RESULTS: Numerous dashboards have been utilized to identify potentially missing data and increase protocol adherence. Immediate patient consultation can occur to retrieve protocol-related forms, reducing research staff and patient burden while improving trial effectiveness. Dashboards can monitor PROs, enrollment, demographics, toxicity, and biomarker data, clinical outcomes, and implemented predictive models, creating a single hub for on-demand clinical trial monitoring. CONCLUSION: By employing a set of freely available tools, the burden of utilizing study staff to continuously monitor trials is greatly reduced. These tools allow users to rapidly build and deploy dynamic dashboards capable of meeting the research needs of any investigator while limiting missing data through simplified monitoring of protocol adherence.

Unplanned implant removal in locally advanced breast cancer.

Study conducted to determine frequency and timing of unplanned breast implant removal after mastectomy, reconstruction, and postmastectomy radiation (PMRT). From 2010-2017, 52 patients underwent mastectomy, reconstruction, and PMRT. With median follow-up of 3.1 years, 23 patients (44%) experienced implant removal. Implant removal occurred in 9 (17%) patients before starting PMRT and 14 (27%) patients after starting PMRT. Implant removal rates were similar for hypofractionated PMRT compared with standard fractionation and for proton compared with photon PMRT. Implant removal is common for women undergoing mastectomy and reconstruction followed by PMRT. The risk is clinically significant even before starting radiation.

Tailoring the Local Environment of Platinum in Single-Atom Pt1 /CeO2 Catalysts for Robust Low-Temperature CO Oxidation.

A single-atom Pt1 /CeO2 catalyst formed by atom trapping (AT, 800 °C in air) shows excellent thermal stability but is inactive for CO oxidation at low temperatures owing to over-stabilization of Pt2+ in a highly symmetric square-planar Pt1 O4 coordination environment. Reductive activation to form Pt nanoparticles (NPs) results in enhanced activity; however, the NPs are easily oxidized, leading to drastic activity loss. Herein we show that tailoring the local environment of isolated Pt2+ by thermal-shock (TS) synthesis leads to a highly active and thermally stable Pt1 /CeO2 catalyst. Ultrafast shockwaves (>1200 °C) in an inert atmosphere induced surface reconstruction of CeO2 to generate Pt single atoms in an asymmetric Pt1 O4 configuration. Owing to this unique coordination, Pt1 δ+ in a partially reduced state dynamically evolves during CO oxidation, resulting in exceptional low-temperature performance. CO oxidation reactivity on the Pt1 /CeO2 _TS catalyst was retained under oxidizing conditions.

Impact of adjuvant trastuzumab on locoregional failure rates in a randomized clinical trial: North Central Cancer Treatment Group N9831 (alliance) study.

BACKGROUND: The goal of this study was to assess the impact of trastuzumab on locoregional failure. METHODS: The analysis included 2763 patients with HER2-positive (HER2+) breast cancer who were randomly assigned to adjuvant doxorubicin (A), cyclophosphamide (C), paclitaxel (T) and trastuzumab (H) (arm A, AC→T [n = 922]; arm B, AC→T→H [n = 988]; arm C, AC→T+H→H [n = 853]). Radiotherapy was given after AC→T concurrently with H. Radiotherapy was given after lumpectomy (L) or after mastectomy (M) with ≥4 positive lymph nodes but was optional for 1 to 3 positive lymph nodes. Locoregional failures at 10 years (LFR10) as first events were compared using competing risk analysis. RESULTS: The median follow-up was 13.0 years. The first site of failure was local-only in 96 cases, locoregional in 16 cases, regional in 32 cases, and not specified in 2 cases; LFR10 was 4.8% (95% CI 4.1%-5.7%). LFR10 was 5.5% (95% CI 4.3%-7.2%), 4.9% (95% CI 3.7%-6.4%), and 2.8% (95% CI 1.9%-4.1%) in arms A, B, and C (B vs A: hazard ratio [HR] 0.91, P = .62; C vs A: HR 0.72, P = .12). For estrogen receptor-positive patients, LFR10 was 3.7% (95% CI 2.8%-4.8%) and for estrogen receptor-negative patients, it was 6.1% (95% CI 5.0%-7.4%; HR 0.61, P = .004). Local treatment included L+RT (n = 1044 [38%]), M+RT (n = 1025 [37%]), and M (n = 694 [25%]). LFR10 was 6.% (95% CI 5.0%-7.8%), 3.0% (95% CI 2.1%-4.3%), and 5.5% (95% CI 4.0%-7.4%) for L+RT, M+RT, and M, respectively (M+RT vs L+RT: HR 0.43, P < .001; M vs L+RT: HR 0.88, P = .57). For 1 to 3 positive lymph nodes, LFR10 was 6.5% (95% CI 4.8%-8.9%), 4.1% (95% CI 2.4%-7.0%), and 4.3% (95% CI 2.9%-6.5%) in L+RT, M+RT, and M, respectively (M vs L+RT: HR 0.68, P = .14; M vs M+RT: HR 1.2, P = .6). CONCLUSION: Low 10-year LFRs were seen regardless of trastuzumab use. Differences in local therapy in patients with 1 to 3 positive lymph nodes did not appear to improve local control. Local therapy studies for HER2+ and other tumor characteristics are important as the role of local therapies continues to evolve.

Acute toxicities after proton beam therapy following breast-conserving surgery for breast cancer: Multi-institutional prospective PCG registry analysis.

We investigated adverse events (AEs) and clinical outcomes for proton beam therapy (PBT) after breast-conserving surgery (BCS) for breast cancer. From 2012 to 2016, 82 patients received PBT in the prospective multi-institutional Proton Collaborative Group registry. AEs were recorded prospectively at each institution. Median follow-up was 8.1 months. Median dose was 50.4 Gy in 28 fractions. Most patients received a lumpectomy bed boost (90%) and regional nodal irradiation (RNI)(83%). Six patients (7.3%) experienced grade 3 AEs (5 with dermatitis, 5 with breast pain). Body mass index (BMI) was associated with grade 3 dermatitis (P = .015). Fifty-eight patients (70.7%) experienced grade ≥2 dermatitis. PBT including RNI after BCS is well-tolerated. Elevated BMI is associated with grade 3 dermatitis.

Proton therapy for thymic malignancies: multi-institutional patterns-of-care and early clinical outcomes from the proton collaborative group and the university of Florida prospective registries.

Objective: Thymic malignancies (TM) are rare tumors with long-term survivorship, causing concerns for radiotherapy-related late side effects. Proton therapy (PT) reduces the radiation dose to organs at risk, potentially decreasing long-term toxicities while preserving disease control. We report patterns-of-care and early clinical outcomes after PT for thymoma and thymic carcinoma. Methods: Between January 2008 and March 2017, 30 patients with TMs enrolled on one of two IRB-approved prospective protocols and received postoperative or definitive PT. Clinical outcomes, pathology, treatment dose, toxicities, and follow-up information were analyzed. Results: Twenty-two thymoma patients with a median age of 52.1 years (range, 23-72) received a median RT dose of 54 Gy (RBE) (range, 45-70) either postoperatively (91%) or definitively (9%); 23% received adjuvant chemotherapy. Among eight thymic carcinoma patients, the median age was 65.5 years (range, 38-88) and median RT dose was 60 Gy (RBE) (range, 42-70) delivered postoperatively (75%) or definitively (25%); 50% received chemotherapy. Median follow-up for all patients was 13 months (range, 2-59 months). Five patients relapsed, one locally (3%). Three patients died of disease progression, including two thymomas and one thymic carcinoma patient; a fourth died of intercurrent disease. One patient with thymic carcinoma and 1 with thymoma are alive with disease. No patients treated with PT for their initial disease (de novo) experienced grade ≥3 toxicities. The most common grade 2 toxicities were dermatitis (37%), cough (13%), and esophagitis (10%). Conclusion: Adjuvant and definitive PT are being used in the treatment of TMs. Early results of the largest such cohort reported to date demonstrates an acceptable rate of recurrence with a favorable toxicity profile. Longer follow-up and a larger patient cohort are needed to confirm these findings.

Proton beam therapy reirradiation for breast cancer: Multi-institutional prospective PCG registry analysis.

To investigate adverse events (AEs, CTCAE v4.0) and clinical outcomes for proton beam therapy (PBT) reirradiation (reRT) for breast cancer. From 2011 to 2016, 50 patients received PBT reRT for breast cancer in the prospective Proton Collaborative Group (PCG) registry. Acute AEs occurred within 180 days from start of reRT. Late AEs began or persisted beyond 180 days. Fisher's exact and Mann-Whitney rank-sum tests were utilized. Kaplan-Meier methods were used to estimate overall survival (OS) and local recurrence-free survival (LFRS). Median follow-up was 12.7 months (0-41.8). Median prior RT dose was 60 Gy (10-96.7). Median reRT dose was 55.1 Gy (45.1-76.3). Median cumulative dose was 110.6 Gy (70.6-156.8). Median interval between RT courses was 103.8 months (5.5-430.8). ReRT included regional nodes in 84% (66% internal mammary node [IMN]). Surgery included the following: 44% mastectomy, 22% wide local excision, 6% lumpectomy, 2% reduction mammoplasty, and 26% no surgery. Grade 3 AEs were experienced by 16% of patients (10% acute, 8% late) and were associated with body mass index (BMI) > 30 kg/m2 (P = 0.04), bilateral recurrence (P = 0.02), and bilateral reRT (P = 0.004). All grade 3 AEs occurred in patients receiving IMN reRT (P = 0.08). At 1 year, LRFS was 93%, and OS was 97%. Patients with gross disease at time of PBT trended toward worse 1-year LRFS (100% without vs. 84% with, P = 0.06). PBT reRT is well tolerated with favorable local control. BMI > 30, bilateral disease, and IMN reRT were associated with grade 3 AEs. Toxicity was acceptable despite median cumulative dose > 110 Gy.

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

Purpose: To report the current practice pattern of the proton stereotactic body radiation therapy (SBRT) for prostate treatments. Materials and Methods: A survey was designed to inquire about the practice of proton SBRT treatment for prostate cancer. The survey was distributed to all 30 proton therapy centers in the United States that participate in the National Clinical Trial Network in February, 2023. The survey focused on usage, patient selection criteria, prescriptions, target contours, dose constraints, treatment plan optimization and evaluation methods, patient-specific QA, and image-guided radiation therapy (IGRT) methods. Results: We received responses from 25 centers (83% participation). Only 8 respondent proton centers (32%) reported performing SBRT of the prostate. The remaining 17 centers cited 3 primary reasons for not offering this treatment: no clinical need, lack of volumetric imaging, and/or lack of clinical evidence. Only 1 center cited the reduction in overall reimbursement as a concern for not offering prostate SBRT. Several common practices among the 8 centers offering SBRT for the prostate were noted, such as using Hydrogel spacers, fiducial markers, and magnetic resonance imaging (MRI) for target delineation. Most proton centers (87.5%) utilized pencil beam scanning (PBS) delivery and completed Imaging and Radiation Oncology Core (IROC) phantom credentialing. Treatment planning typically used parallel opposed lateral beams, and consistent parameters for setup and range uncertainties were used for plan optimization and robustness evaluation. Measurements-based patient-specific QA, beam delivery every other day, fiducial contours for IGRT, and total doses of 35 to 40 GyRBE were consistent across all centers. However, there was no consensus on the risk levels for patient selection. Conclusion: Prostate SBRT is used in about 1/3 of proton centers in the US. There was a significant consistency in practices among proton centers treating with proton SBRT. It is possible that the adoption of proton SBRT may become more common if proton SBRT is more commonly offered in clinical trials.

Beam mask and sliding window-facilitated deep learning-based accurate and efficient dose prediction for pencil beam scanning proton therapy.

BACKGROUND: Accurate and efficient dose calculation is essential for on-line adaptive planning in proton therapy. Deep learning (DL) has shown promising dose prediction results in photon therapy. However, there is a scarcity of DL-based dose prediction methods specifically designed for proton therapy. Successful dose prediction method for proton therapy should account for more challenging dose prediction problems in pencil beam scanning proton therapy (PBSPT) due to its sensitivity to heterogeneities. PURPOSE: To develop a DL-based PBSPT dose prediction workflow with high accuracy and balanced complexity to support on-line adaptive proton therapy clinical decision and subsequent replanning. METHODS: PBSPT plans of 103 prostate cancer patients (93 for training and the other 10 for independent testing) and 83 lung cancer patients (73 for training and the other 10 for independent testing) previously treated at our institution were included in the study, each with computed tomography scans (CTs), structure sets, and plan doses calculated by the in-house developed Monte-Carlo dose engine (considered as the ground truth in the model training and testing). For the ablation study, we designed three experiments corresponding to the following three methods: (1) Experiment 1, the conventional region of interest (ROI) (composed of targets and organs-at-risk [OARs]) method. (2) Experiment 2, the beam mask (generated by raytracing of proton beams) method to improve proton dose prediction. (3) Experiment 3, the sliding window method for the model to focus on local details to further improve proton dose prediction. A fully connected 3D-Unet was adopted as the backbone. Dose volume histogram (DVH) indices, 3D Gamma passing rates with a criterion of 3%/3 mm/10%, and dice coefficients for the structures enclosed by the iso-dose lines between the predicted and the ground truth doses were used as the evaluation metrics. The calculation time for each proton dose prediction was recorded to evaluate the method's efficiency. RESULTS: Compared to the conventional ROI method, the beam mask method improved the agreement of DVH indices for both targets and OARs and the sliding window method further improved the agreement of the DVH indices (for lung cancer, CTV D98 absolute deviation: 0.74 ± 0.18 vs. 0.57 ± 0.21 vs. 0.54 ± 0.15 Gy[RBE], ROI vs. beam mask vs. sliding window methods, respectively). For the 3D Gamma passing rates in the target, OARs, and BODY (outside target and OARs), the beam mask method improved the passing rates in these regions and the sliding window method further improved them (for prostate cancer, targets: 96.93% ± 0.53% vs. 98.88% ± 0.49% vs. 99.97% ± 0.07%, BODY: 86.88% ± 0.74% vs. 93.21% ± 0.56% vs. 95.17% ± 0.59%). A similar trend was also observed for the dice coefficients. This trend was especially remarkable for relatively low prescription isodose lines (for lung cancer, 10% isodose line dice: 0.871 ± 0.027 vs. 0.911 ± 0.023 vs. 0.927 ± 0.017). The dose predictions for all the testing cases were completed within 0.25 s. CONCLUSIONS: An accurate and efficient deep learning-augmented proton dose prediction framework has been developed for PBSPT, which can predict accurate dose distributions not only inside but also outside ROI efficiently. The framework can potentially further reduce the initial planning and adaptive replanning workload in PBSPT.

The status and challenges for prostate SBRT treatments in United States proton therapy centers: An NRG Oncology practice survey.

A survey was designed to inquire about the practice of proton SBRT treatment for prostate cancer. The survey was distributed to all 30 proton therapy centers in the United States that participate in the National Clinical Trial Network in Feb. 2023. The survey focused on usage, patient selection criteria, prescriptions, target contours, dose constraints, treatment plan optimization and evaluation methods, patient-specific QA, and IGRT methods. Results: We received responses from 25 centers (83% participation). Only 8 respondent proton centers (32%) reported performing SBRT of the prostate. The remaining 17 centers cited three primary reasons for not offering this treatment: no clinical need, lack of volumetric imaging, and/or lack of clinical evidence. Only 1 center cited the reduction in overall reimbursement as a concern for not offering prostate SBRT. Several common practices among the 8 centers offering SBRT for the prostate were noted, such as using Hydrogel spacers, fiducial markers, and MRI for target delineation. Most proton centers (87.5%) utilized pencil beam scanning (PBS) delivery and completed Imaging and Radiation Oncology Core (IROC) phantom credentialing. Treatment planning typically used parallel opposed lateral beams, and consistent parameters for setup and range uncertainties were used for plan optimization and robustness evaluation. Measurements-based patient-specific QA, beam delivery every other day, fiducial contours for IGRT, and total doses of 35-40 GyRBE were consistent across all centers. However, there was no consensus on the risk levels for patient selection. Conclusion: Prostate SBRT is used in about 1/3 of proton centers in the US. There was a significant consistency in practices among proton centers treating with proton SBRT. It is possible that the adoption of proton SBRT may become more common if proton SBRT is more commonly offered in clinical trials.

Predicting the Effect of Proton Beam Therapy Technology on Pulmonary Toxicities for Patients With Locally Advanced Lung Cancer Enrolled in the Proton Collaborative Group Prospective Clinical Trial.

PURPOSE: This study aimed to predict the probability of grade ≥2 pneumonitis or dyspnea within 12 months of receiving conventionally fractionated or mildly hypofractionated proton beam therapy for locally advanced lung cancer using machine learning. METHODS AND MATERIALS: Demographic and treatment characteristics were analyzed for 965 consecutive patients treated for lung cancer with conventionally fractionated or mildly hypofractionated (2.2-3 Gy/fraction) proton beam therapy across 12 institutions. Three machine learning models (gradient boosting, additive tree, and logistic regression with lasso regularization) were implemented to predict Common Terminology Criteria for Adverse Events version 4 grade ≥2 pulmonary toxicities using double 10-fold cross-validation for parameter hyper-tuning without leak of information. Balanced accuracy and area under the curve were calculated, and 95% confidence intervals were obtained using bootstrap sampling. RESULTS: The median age of the patients was 70 years (range, 20-97), and they had predominantly stage IIIA or IIIB disease. They received a median dose of 60 Gy in 2 Gy/fraction, and 46.4% received concurrent chemotherapy. In total, 250 (25.9%) had grade ≥2 pulmonary toxicity. The probability of pulmonary toxicity was 0.08 for patients treated with pencil beam scanning and 0.34 for those treated with other techniques (P = 8.97e-13). Use of abdominal compression and breath hold were highly significant predictors of less toxicity (P = 2.88e-08). Higher total radiation delivered dose (P = .0182) and higher average dose to the ipsilateral lung (P = .0035) increased the likelihood of pulmonary toxicities. The gradient boosting model performed the best of the models tested, and when demographic and dosimetric features were combined, the area under the curve and balanced accuracy were 0.75 ± 0.02 and 0.67 ± 0.02, respectively. After analyzing performance versus the number of data points used for training, we observed that accuracy was limited by the number of observations. CONCLUSIONS: In the largest analysis of prospectively enrolled patients with lung cancer assessing pulmonary toxicities from proton therapy to date, advanced machine learning methods revealed that pencil beam scanning, abdominal compression, and lower normal lung doses can lead to significantly lower probability of developing grade ≥2 pneumonitis or dyspnea.

Stereotactic Body Proton Therapy Versus Conventionally Fractionated Proton Therapy for Early Prostate Cancer: A Randomized, Controlled, Phase 3 Trial.

PURPOSE: We aimed to determine if ultra-hypofractionated proton therapy delivered via stereotactic body proton therapy (SBPT) is non-inferior to conventionally fractionated proton therapy (CFPT) in patients with early prostate cancer. MATERIALS AND METHODS: This study was a multicenter, randomized, controlled, non-inferiority phase 3 trial that included patients with histologically confirmed low-risk prostate adenocarcinoma defined by Gleason score grouping 1, PSA <10 ng/mL, and clinical stage T1-2a N0 M0 according to AJCC 7th ed. Eligible participants were randomly assigned initially at a 1:1 ratio and later at a 2:1 ratio to SBPT (38 Gy in 5 fractions) or CFPT (79.2 Gy in 44 fractions). The primary endpoint was freedom from failure (FFF) at 2 years from the date of randomization. Non-inferiority for FFF was determined based on one-sided confidence intervals. Toxicities were compared at different time points using Fisher's Exact test. Health-related quality-of-life (HRQoL) was analyzed at different time points using a mixed-effects linear model. This trial is registered with ClinicalTrials.gov, NCT01230866, and is closed to accrual. RESULTS: Between December 10, 2010, and September 29, 2020, 144 patients were enrolled and 135 were randomly assigned (90 to the SBPT group and 45 to the CFPT group). The median follow-up was 5 years (IQR 3.9-5.2). The 2-year FFF was 100% for both groups, with the one-sided 5-year risk difference in FFF between groups reported as 2.63% (90% CI: -1.70%-6.96%), favoring the SBRT arm, thus fulfilling the pre-specified criteria for non-inferiority of SBPT compared to CFPT. Rates of gastrointestinal (GI) and genitourinary (GU) G2 and G3 toxicities did not differ significantly between groups but the the study was not powered to detect significant toxicity differences. Also, HRQoL metrics did not differ significantly between groups over the study median follow up. CONCLUSIONS: SBPT is non-inferior to CFPT regarding FFF, with similar long-term GU and GI toxicity rates and minimal impact in patient reported HRQoL over time.

Physician- and Patient-Reported Outcomes of the MC1635 Phase 3 Trial of Ultrahypofractionated Versus Moderately Hypofractionated Adjuvant Radiation Therapy After Breast-Conserving Surgery.

PURPOSE: Our aim was to report physician- and patient-reported outcomes of patients with localized breast cancer treated with moderate versus ultrahypofractionated whole breast irradiation (WBI) after breast-conserving surgery (BCS). METHODS AND MATERIALS: Between February 2018 and February 2020, patients with localized breast cancer (pT0-3 pN0-1 M0) were offered participation in a phase 3 randomized clinical trial assessing adjuvant moderate hypofractionation (MHF) to 40 Gy in 15 fractions versus ultrahypofractionation (UHF) to 25 Gy in 5 fractions after BCS, with an optional simultaneously integrated boost. Toxicities, cosmesis, and quality of life were assessed at baseline, end of treatment (EOT), and 3 months, 1 year, 2 years, and 3 years from irradiation using validated metric tools. RESULTS: One hundred seven patients were randomized to MHF (n = 54) or UHF (n = 53) adjuvant WBI. The median follow-up was 42.8 months. Grade 2 radiation dermatitis was experienced by 4 patients (7.4%) in the MHF arm and 2 patients (3.7%) in the UHF arm at EOT (P = .726). No grade 3 or higher toxicities were observed. Deterioration of cosmesis by physician assessment was observed in 2 (6.7%) patients treated in the UHF arm and 1 (1.9%) patient treated in the MHF arm at EOT (P = .534), whereas at 3 months, only 1 (1.8%) patient treated in the MHF arm demonstrated deterioration of cosmesis (P = .315). At EOT, 91% and 94% of patients reported excellent/good cosmesis among those treated with MHF and UHF regimens, respectively (P = .550). At 3 months, more patients within the MHF arm reported excellent/good cosmesis compared with those in the UHF arm (100% vs 91%; P = .030). However, the difference in patient-reported cosmesis disappeared at the 1-, 2-, and 3-year time points. CONCLUSIONS: UHF WBI showed similar treatment-related late toxicities and similar provider-scored cosmesis compared with MHF radiation in patients treated adjuvantly after BCS.

Atrial Fibrillation: Rate Versus Rhythm Control.

Description Atrial fibrillation (AF) remains the most common arrhythmia worldwide and is expected to affect approximately 12 million individuals in the United States alone by 2030. Thromboembolic events remain a feared complication of AF and should be treated and risk-stratified utilizing the CHA2DS2-VASc scoring system. Other complications of AF span a wide spectrum from impaired quality of life (QoL) to an increase in all-cause mortality. Rate control strategies consist of controlling the ventricular rate and have been shown to be a safe and effective strategy for asymptomatic AF patients. In patients who are plagued with symptoms leading to impaired QoL or a decrease in exercise capacity, rhythm control with antiarrhythmic drugs or catheter ablation may be suitable options. Mortality benefits when comparing rate versus rhythm control remain equivocal when comparing multiple studies over the past decade.