Assessment of minimum target dose as a predictor of local failure after spine SBRT.

OBJECTIVES: Metastasis-directed stereotactic body radiation therapy (SBRT) has demonstrated robust clinical benefits in carefully selected patients, improving local control and even overall survival (OS). We assess a large database to determine clinical and dosimetric predictors of local failure after spine SBRT. METHODS: Spine SBRT treatments with imaging follow-up were identified. Patients were treated with a simultaneous integrated boost technique using 1 or 3 fractions, delivering 20-24 Gy in 1 fraction to the gross tumor volume (GTV) and 16 Gy to the low dose volume (or 27-36 Gy and 21-24 Gy for 3 fraction treatments). Exclusions included: lack of imaging follow-up, proton therapy, and benign primary histologies. RESULTS: 522 eligible spine SBRT treatments (68 % single fraction) were identified in 377 unique patients. Patients had a median OS of 43.7 months (95 % confidence interval: 34.3-54.4). The cumulative incidence of local failure was 10.5 % (7.4-13.4) at 1 year and 16.3 % (12.6-19.9) at 2 years. Local control was maximized at 15.3 Gy minimum dose for single-fraction treatment (HR = 0.31, 95 % CI: 0.17 - 0.56, p < 0.0001) and confirmed via multivariable analyses. Cumulative incidence of local failure was 6.1 % (2.6-9.4) vs. 14.2 % (8.3-19.8) at 1 year using this cut-off, with comparable findings for minimum 14 Gy. Additionally, epidural and soft tissue involvement were predictive of local failure (HR = 1.77 and 2.30). CONCLUSIONS: Spine SBRT offers favorable local control; however, minimum dose to the GTV has a strong association with local control. Achieving GTV minimum dose of 14-15.3 Gy with single fraction SBRT is recommended whenever possible.

Automated target placement for VMAT lattice radiation therapy: enhancing efficiency and consistency.

Objective. An algorithm was developed for automated positioning of lattice points within volumetric modulated arc lattice radiation therapy (VMAT LRT) planning. These points are strategically placed within the gross tumor volume (GTV) to receive high doses, adhering to specific separation rules from adjacent organs at risk (OARs). The study goals included enhancing planning safety, consistency, and efficiency while emulating human performance.Approach. A Monte Carlo-based algorithm was designed to optimize the number and arrangement of lattice points within the GTV while considering placement constraints and objectives. These constraints encompassed minimum spacing between points, distance from OARs, and longitudinal separation along thez-axis. Additionally, the algorithm included an objective to permit, at the user's discretion, solutions with more centrally placed lattice points within the GTV. To validate its effectiveness, the automated approach was compared with manually planned treatments for 24 previous patients. Prior to clinical implementation, a failure mode and effects analysis (FMEA) was conducted to identify potential shortcomings.Main results.The automated program successfully met all placement constraints with an average execution time (over 24 plans) of 0.29 ±0.07 min per lattice point. The average lattice point density (# points per 100 c.c. of GTV) was similar for automated (0.725) compared to manual placement (0.704). The dosimetric differences between the automated and manual plans were minimal, with statistically significant differences in certain metrics like minimum dose (1.9% versus 1.4%), D5% (52.8% versus 49.4%), D95% (7.1% versus 6.2%), and Body-GTV V30% (20.7 c.c. versus 19.7 c.c.).Significance.This study underscores the feasibility of employing a straightforward Monte Carlo-based algorithm to automate the creation of spherical target structures for VMAT LRT planning. The automated method yields similar dose metrics, enhances inter-planner consistency for larger targets, and requires fewer resources and less time compared to manual placement. This approach holds promise for standardizing treatment planning in prospective patient trials and facilitating its adoption across centers seeking to implement VMAT LRT techniques.

Treatment modalities and survival outcomes in prostate cancer parenchymal brain metastasis.

BACKGROUND: Prostate cancer (PCa) parenchymal brain metastases are uncommon and troubling observations in the course of the disease. Our study aims to evaluate the prevalence of brain metastases among PCa patients while reporting various therapeutic modalities, clinical features, and oncological outcomes. METHODS: We retrospectively identified 34 patients with parenchymal brain metastasis out of 4575 patients using a prospectively maintained database that contains clinicopathologic characteristics of PCa patients between January 2012 and December 2021. Based on the three treatment modalities used, the patients were divided into three groups: stereotactic radiosurgery (SRS), whole brain radiotherapy (WBRT), and systemic therapy alone. The Kaplan-Meier curve was used to calculate overall survival [OS] probability and the Cox proportional hazards regression model was used to compare between groups. RESULTS: At the time of brain metastasis diagnosis, the median age was 66 years, the median (interquartile range [IQR]) prostate-specific antigen (PSA) was 2.2 (0.1-26.6) ng/ml and the median (IQR) months from initial PCa diagnosis to brain metastasis development was 70.8 (27.6-100.9). The median (IQR) primary Gleason score was 8 (7-9) and over a median (IQR) follow-up time of 2.2 (1.2-16.5) months, 76.5% (n = 26) of the patients died. Thirteen (38.2%) patients had solitary lesion, whereas 21 (61.8%) had ≥2 lesions. The lesions were supratentorial in 19 (55.9%) patients, infratentorial in six (17.6%), and both sides in nine (26.5%). Among all 34 patients, 10 (29.4%) were treated with SRS, seven (20.6%) with WBRT, and 17 (50%) with systemic therapy alone. OS varied greatly between the three treatment modalities (log-rank test, p = 0.049). Those who were treated with SRS and WBRT had better OS compared with patients who were treated with systemic therapy alone (hazard ratio: 0.37, 95% confidence interval: 0.16-0.86, p = 0.022). CONCLUSIONS: In our single-institutional study, we confirmed that PCa brain metastasis is associated with poor survival outcomes and more advanced metastatic disease. Furthermore, we found that SRS and WBRT for brain metastasis in patients with recurrent PCa appear to be associated with improved OS as compared with systemic therapy alone and are likely secondary to selection bias.

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.

Sublobar Resection, Stereotactic Body Radiation Therapy, and Percutaneous Ablation Provide Comparable Outcomes for Lung Metastasis-Directed Therapy.

BACKGROUND: Prolonged survival of patients with metastatic disease has furthered interest in metastasis-directed therapy (MDT). RESEARCH QUESTION: There is a paucity of data comparing lung MDT modalities. Do outcomes among sublobar resection (SLR), stereotactic body radiation therapy (SBRT), and percutaneous ablation (PA) for lung metastases vary in terms of local control and survival? STUDY DESIGN AND METHODS: Medical records of patients undergoing lung MDT at a single cancer center between January 2015 and December 2020 were reviewed. Overall survival, local progression, and toxicity outcomes were collected. Patient and lesion characteristics were used to generate multivariable models with propensity weighted analysis. RESULTS: Lung MDT courses (644 total: 243 SLR, 274 SBRT, 127 PA) delivered to 511 patients were included with a median follow-up of 22 months. There were 47 local progression events in 45 patients, and 159 patients died. Two-year overall survival and local progression were 80.3% and 63.3%, 83.8% and 9.6%, and 4.1% and 11.7% for SLR, SBRT, and PA, respectively. Lesion size per 1 cm was associated with worse overall survival (hazard ratio, 1.24; P = .003) and LP (hazard ratio, 1.50; P < .001). There was no difference in overall survival by modality. Relative to SLR, there was no difference in risk of local progression with PA; however, SBRT was associated with a decreased risk (hazard ratio, 0.26; P = .023). Rates of severe toxicity were low (2.1%-2.6%) and not different among groups. INTERPRETATION: This study performs a propensity weighted analysis of SLR, SBRT, and PA and shows no impact of lung MDT modality on overall survival. Given excellent local control across MDT options, a multidisciplinary approach is beneficial for patient triage and longitudinal management.

Salvage therapy expands highly cytotoxic and metabolically fit resilient CD8+ T cells via ME1 up-regulation.

Patients with advanced cancers who either do not experience initial response to or progress while on immune checkpoint inhibitors (ICIs) receive salvage radiotherapy to reduce tumor burden and tumor-related symptoms. Occasionally, some patients experience substantial global tumor regression with a rebound of cytotoxic CD8+ T cells. We have termed the rebound of cytotoxic CD8+ T cells in response to salvage therapy as T cell resilience and examined the underlying mechanisms of resilience. Resilient T cells are enriched for CX3CR1+ CD8+ T cells with low mitochondrial membrane potential, accumulate less reactive oxygen species (ROS), and express more malic enzyme 1 (ME1). ME1 overexpression enhanced the cytotoxicity and expansion of effector CD8+ T cells partially via the type I interferon pathway. ME1 also increased mitochondrial respiration while maintaining the redox state balance. ME1 increased the cytotoxicity of peripheral lymphocytes from patients with advanced cancers. Thus, preserved resilient T cells in patients rebound after salvage therapy and ME1 enhances their resiliency.

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.

Auxiliary liver xenotransplantation technique in a transgenic pig-to-non-human primate model: A surgical approach to prolong survival.

Xenotransplantation using pigs' liver offers a potentially alternative method to overcome worldwide donor shortage, or more importantly as a bridge to allotransplantation. However, it has been challenged by profound thrombocytopenia and fatal coagulopathy in non-human primate models. Here we suggest that a left auxiliary technique can be a useful method to achieve extended survival of the xenograft. Fifteen consecutive liver xenotransplants were carried out in a pig-to-cynomolgus model. Right auxiliary technique was implemented in two cases, orthotopic in eight cases, and left auxiliary in five cases. None of the right auxiliary recipients survived after surgery due to hemorrhage during complex dissection between the primate's right lobe and inferior vena cava. Orthotopic recipients survived less than 7 days secondary to profound thrombocytopenia and coagulopathy. Two out of five left auxiliary xenotransplants survived more than 3 weeks without uncontrolled thrombocytopenia or anemia, with one of them surviving 34 days, the longest graft survival reported to date. Left auxiliary xenotransplant is a feasible approach in non-human primate experiments, and the feared risk of thrombocytopenia and coagulopathy can be minimized. This may allow for longer evaluation of the xenograft and help better understand histopathological and immunological changes that occur following liver xenotransplantation.

Effect of pre-operative radiation therapy on surgical outcome in retroperitoneal sarcoma.

Background: A high rate of locoregional recurrence is one of the major difficulties in successful treatment of retroperitoneal sarcoma (RPS). Although pre-operative radiation therapy (RT) is considered a potential way to improve local recurrence, concerns about the associated treatment toxicity and risk of peri-operative complications need to be addressed. Hence, this study investigates the safety of pre-operative RT (preRTx) for RPS. Methods: A cohort of 198 patients with RPS who had undergone both surgery and RT was analyzed for peri-operative complications. They were divided into three groups according to the RT scheme: (1) preRTx group, (2) post-operative RT without tissue expander, and (3) post-operative RT with tissue expander. Results: The preRTx was overall well tolerated and did not affect the R2 resection rate, operative time, and severe post-operative complications. However, the preRTx group was associated with higher incidence of post-operative transfusion and admission to intensive care unit (p = 0.013 and p = 0.036, respectively), where preRTx was an independent risk factor only for the post-operative transfusion (p = 0.009) in multivariate analysis. The median radiation dose was the highest in preRTx group, although no significant difference was demonstrated in overall survival and local recurrence rate. Conclusion: This study suggests that the preRTx does not add significant post-operative morbidity to the patients with RPS. In addition, radiation dose elevation is achievable with the pre-operative RT. However, a meticulous intra-operative bleeding control is recommended in those patients, and further high-quality trials are warranted to evaluate the long-term oncological outcomes.

Clinical aspects of spatially fractionated radiation therapy treatments.

PURPOSE: To provide clinical guidance for centers wishing to implement photon spatially fractionated radiation therapy (SFRT) treatments using either a brass grid or volumetric modulated arc therapy (VMAT) lattice approach. METHODS: We describe in detail processes which have been developed over the course of a 3-year period during which our institution treated over 240 SFRT cases. The importance of patient selection, along with aspects of simulation, treatment planning, quality assurance, and treatment delivery are discussed. Illustrative examples involving clinical cases are shown, and we discuss safety implications relevant to the heterogeneous dose distributions. RESULTS: SFRT can be an effective modality for tumors which are otherwise challenging to manage with conventional radiation therapy techniques or for patients who have limited treatment options. However, SFRT has several aspects which differ drastically from conventional radiation therapy treatments. Therefore, the successful implementation of an SFRT treatment program requires the multidisciplinary expertise and collaboration of physicians, physicists, dosimetrists, and radiation therapists. CONCLUSIONS: We have described methods for patient selection, simulation, treatment planning, quality assurance and delivery of clinical SFRT treatments which were built upon our experience treating a large patient population with both a brass grid and VMAT lattice approach. Preclinical research and patient trials aimed at understanding the mechanism of action are needed to elucidate which patients may benefit most from SFRT, and ultimately expand its use.

Postmastectomy Intensity Modulated Proton Therapy: 5-Year Oncologic and Patient-Reported Outcomes.

PURPOSE: To report oncologic, physician-assessed, and patient-reported outcomes (PROs) for a group of women homogeneously treated with modern, skin-sparing multifield optimized pencil-beam scanning proton (intensity modulated proton therapy [IMPT]) postmastectomy radiation therapy (PMRT). METHODS AND MATERIALS: We reviewed consecutive patients who received unilateral, curative-intent, conventionally fractionated IMPT PMRT between 2015 and 2019. Strict constraints were applied to limit the dose to the skin and other organs at risk. Five-year oncologic outcomes were analyzed. Patient-reported outcomes were evaluated as part of a prospective registry at baseline, completion of PMRT, and 3 and 12 months after PMRT. RESULTS: A total of 127 patients were included. One hundred nine (86%) received chemotherapy, among whom 82 (65%) received neoadjuvant chemotherapy. The median follow-up was 4.1 years. Five-year locoregional control was 98.4% (95% CI, 93.6-99.6), and overall survival was 87.9% (95% CI, 78.7-96.5). Acute grade 2 and 3 dermatitis was seen in 45% and 4% of patients, respectively. Three patients (2%) experienced acute grade 3 infection, all of whom had breast reconstruction. Three late grade 3 adverse events occurred: morphea (n = 1), infection (n = 1), and seroma (n = 1). There were no cardiac or pulmonary adverse events. Among the 73 patients at risk for PMRT-associated reconstruction complications, 7 (10%) experienced reconstruction failure. Ninety-five patients (75%) enrolled in the prospective PRO registry. The only metrics to increase by >1 point were skin color (mean change: 5) and itchiness (2) at treatment completion and tightness/pulling/stretching (2) and skin color (2) at 12 months. There was no significant change in the following PROs: bleeding/leaking fluid, blistering, telangiectasia, lifting, arm extension, or bending/straightening the arm. CONCLUSIONS: With strict dose constraints to skin and organs at risk, postmastectomy IMPT was associated with excellent oncologic outcomes and PROs. Rates of skin, chest wall, and reconstruction complications compared favorably to previous proton and photon series. Postmastectomy IMPT warrants further investigation in a multi-institutional setting with careful attention to planning techniques.

Long-term outcomes of intraoperatively-placed applicator brachytherapy for rapid completion of breast conserving treatment: An analysis of a prospective registry data.

Background and purpose: To evaluate the long-term outcome of accelerated partial breast irradiation utilizing intraoperatively placed applicator-based brachytherapy (ABB) in early-stage breast cancer. Materials and methods: From our prospective registry, 223 patients with pTis-T2, pN0/pN1mic breast cancer were treated with ABB. The median treatment duration including surgery and ABB was 7 days. The prescribed doses were 32 Gy/8 fx BID (n = 25), 34 Gy/10 fx BID (n = 99), and 21 Gy/3 fx QD (n = 99). Endocrine therapy (ET) adherence was defined as completion of planned ET or ≥ 80% of the follow-up (FU) period. Cumulative incidence of ipsilateral breast tumor recurrence (IBTR) was estimated and influencing factors for IBTR-free survival rate (IBTRFS) were analyzed. Results: 218/223 patients had hormone receptor-positive tumors, including 38 (17.0%) with Tis and 185 (83.0%) with invasive cancer. After a median FU of 63 months, 19 (8.5%) patients had recurrence [17 (7.6%) with an IBTR]. Rates of 5-year IBTRFS and DFS were 92.2% and 91.1%, respectively. The 5-year IBTRFS rates were significantly higher for post-menopausal women (93.6% vs. 66.4%, p = 0.04), BMI < 30 kg/m2 (97.4% vs. 88.1%, p = 0.02), and ET-adherence (97.5% vs. 88.6%, p = 0.02). IBTRFS did not differ with dose regimens. Conclusions: Postmenopausal status, BMI < 30 kg/m2, and ET- adherence predicted favorable IBTRFS. Our results highlight the importance of careful patient selection for ABB and encouragement of ET compliance.

Development and validation of a recursive partitioning analysis-based pretreatment decision-making tool identifying ideal candidates for spine stereotactic body radiation therapy.

BACKGROUND: This study was aimed at developing and validating a decision-making tool predictive of overall survival (OS) for patients receiving stereotactic body radiation therapy (SBRT) for spinal metastases. METHODS: Three hundred sixty-one patients at one institution were used for the training set, and 182 at a second institution were used for external validation. Treatments most commonly involved one or three fractions of spine SBRT. Exclusion criteria included proton therapy and benign histologies. RESULTS: The final model consisted of the following variables and scores: Spinal Instability Neoplastic Score (SINS) ≥ 6 (1), time from primary diagnosis < 21 months (1), Eastern Cooperative Oncology Group (ECOG) performance status = 1 (1) or ECOG performance status > 1 (2), and >1 organ system involved (1). Each variable was an independent predictor of OS (p < .001), and each 1-point increase in the score was associated with a hazard ratio of 2.01 (95% confidence interval [CI], 1.79-2.25; p < .0001). The concordance value was 0.75 (95% CI, 0.71-0.78). The scores were discretized into three groups-favorable (score = 0-1), intermediate (score = 2), and poor survival (score = 3-5)-with 2-year OS rates of 84% (95% CI, 79%-90%), 46% (95% CI, 36%-59%), and 21% (95% CI, 14%-32%), respectively (p < .0001 for each). In the external validation set (182 patients), the score was also predictive of OS (p < .0001). Increasing SINS was predictive of decreased OS as a continuous variable (p < .0001). CONCLUSIONS: This novel score is proposed as a decision-making tool to help to optimize patient selection for spine SBRT. SINS may be an independent predictor of OS.

Evaluation of a New, Highly Flexible Radiofrequency Coil for MR Simulation of Patients Undergoing External Beam Radiation Therapy.

PURPOSE: To evaluate the performance of a new, highly flexible radiofrequency (RF) coil system for imaging patients undergoing MR simulation. METHODS: Volumetric phantom and in vivo images were acquired with a commercially available and prototype RF coil set. Phantom evaluation was performed using a silicone-filled humanoid phantom of the head and shoulders. In vivo assessment was performed in five healthy and six patient subjects. Phantom data included T1-weighted volumetric imaging, while in vivo acquisitions included both T1- and T2-weighted volumetric imaging. Signal to noise ratio (SNR) and uniformity metrics were calculated in the phantom data, while SNR values were calculated in vivo. Statistical significance was tested by means of a non-parametric analysis of variance test. RESULTS: At a threshold of p = 0.05, differences in measured SNR distributions within the entire phantom volume were statistically different in two of the three paired coil set comparisons. Differences in per slice average SNR between the two coil sets were all statistically significant, as well as differences in per slice image uniformity. For patients, SNRs within the entire imaging volume were statistically significantly different in four of the nine comparisons and seven of the nine comparisons performed on the per slice average SNR values. For healthy subjects, SNRs within the entire imaging volume were statistically significantly different in seven of the nine comparisons and eight of the nine comparisons when per slice average SNR was tested. CONCLUSIONS: Phantom and in vivo results demonstrate that image quality obtained from the novel flexible RF coil set was similar or improved over the conventional coil system. The results also demonstrate that image quality is impacted by the specific coil configurations used for imaging and should be matched appropriately to the anatomic site imaged to ensure optimal and reproducible image quality.

Recoverability of Diabetic Nephropathy of Donor Kidney After Kidney Transplantation.

Some kidney donors have diabetes, and little of their natural course of diabetic nephropathy (DN) is known. The aim of this study was to analyze the changes in pathologic lesions in the diabetic donor kidney after KT by performing protocol biopsy two weeks and one year after KT. This retrospective study included 103 patients who underwent KT, with kidneys from donors with a history of diabetes mellitus (DM). Among them, data of 34 patients who underwent biopsy two weeks and one year after KT were reviewed. Biopsy specimens were reviewed using light microscopy and electron microscopy. Glomerular basement membrane (GBM) thickness at 2 weeks and 1 year was compared. Biopsy showed that DN occurred in 29 of the 34 patients. Only trivial histological changes were observed in 22 patients (64.7%), including 5 patients who did not show DN. At one year after transplantation, there was no change in the DN histologic class in 26 patients (76.5%), and there was no statistically significant difference in the change in GBM thickness. This pattern was observed regardless of the recipient's DM or glycemic control. With this understanding, clinicians can use kidneys from DM donors with more comfort, thereby reducing the kidney discard rate.

Single and Multifraction Spine Stereotactic Body Radiation Therapy and the Risk of Radiation Induced Myelopathy.

Purpose: This study reports on the risk of radiation-induced myelitis (RM) of the spinal cord from a large single-institutional experience with 1 to 5 fraction stereotactic body radiation therapy (SBRT) to the spine. Methods and Materials: A retrospective review of patients who received spine SBRT to a radiation naïve level at or above the conus medullaris between 2007 and 2019 was performed. Local failure determination was based on SPIne response assessment in Neuro-Oncology criteria. RM was defined as neurologic symptoms consistent with the segment of cord irradiated in the absence of neoplastic disease recurrence and graded by Common Toxicity Criteria for Adverse Events, version 4.0. Rates of adverse events were estimated and dose-volume statistics from delivered treatment plans were extracted for the planning target volumes and spinal cord. Results: A total of 353 lesions in 277 patients were identified that met the specified criteria, for which 270, 70, and 13 lesions received 1-, 3-, and 5-fraction treatments, respectively, with a median follow-up of 46 months (95% confidence interval [CI], 41-52 months) for all surviving patients. The median overall survival was 33.0 months (95% CI, 29-43). The median D0.03cc to the spinal cord was 11.7 Gy (interquartile range [IQR], 10.5-12.4), 16.7 Gy (IQR, 12.8-20.6), and 26.0 Gy (IQR, 24.1-28.1), for 1-, 3-, 5-fractions. Using an a/b = 2Gy for the spinal cord, the median single-fraction equivalent-dose (SFED2) was 11.7 Gy (IQR, 10.2-12.5 Gy) and the normalized biological equivalent dose (nBED2/2) was 19.9 Gy (IQR, 15.4-22.8 Gy). One patient experienced grade 2 RM after a single-fraction treatment. The cumulative probability of RM was 0.3% (95% CI, 0%-2%). Conclusions: Spine SBRT is safe while limiting the spinal cord (as defined on treatment planning magnetic resonance imaging or computed tomography myelogram) D0.03cc to less than 14 Gy, 21.9 Gy, and 30 Gy, for 1, 3, and 5-fractions, consistent with standard guidelines.

Cardiopulmonary Toxicity Following Intensity-Modulated Proton Therapy (IMPT) Versus Intensity-Modulated Radiation Therapy (IMRT) for Stage III Non-Small Cell Lung Cancer.

INTRODUCTION: Intensity-modulated proton therapy (IMPT) has the potential to reduce radiation dose to normal organs when compared to intensity-modulated radiation therapy (IMRT). We hypothesized that IMPT is associated with a reduced rate of cardiopulmonary toxicities in patients with Stage III NSCLC when compared with IMRT. METHODS: We analyzed 163 consecutively treated patients with biopsy-proven, stage III NSCLC who received IMPT (n = 35, 21%) or IMRT (n = 128, 79%). Patient, tumor, and treatment characteristics were analyzed. Overall survival (OS), freedom-from distant metastasis (FFDM), freedom-from locoregional relapse (FFLR), and cardiopulmonary toxicities (CTCAE v5.0) were calculated using the Kaplan-Meier estimate. Univariate cox regressions were conducted for the final model. RESULTS: Median follow-up of surviving patients was 25.5 (range, 4.6-58.1) months. Median RT dose was 60 (range, 45-72) Gy [RBE]. OS, FFDM, and FFLR were not different based on RT modality. IMPT provided significant dosimetric pulmonary and cardiac sparing when compared to IMRT. IMPT was associated with a reduced rate of grade more than or equal to 3 pneumonitis (HR 0.25, P = .04) and grade more than or equal to 3 cardiac events (HR 0.33, P = .08). Pre-treatment predicted diffusing capacity for carbon monoxide less than equal to 57% (HR 2.8, P = .04) and forced expiratory volume in the first second less than equal to 61% (HR 3.1, P = .03) were associated with an increased rate of grade more than or equal to 3 pneumonitis. CONCLUSIONS: IMPT is associated with a reduced risk of clinically significant pneumonitis and cardiac events when compared with IMRT without compromising tumor control in stage III NSCLC. IMPT may provide a safer treatment option, particularly for high-risk patients with poor pretreatment pulmonary function.

Stereotactic Body Radiation Therapy for Metastases in Long Bones.

PURPOSE: To evaluate the cumulative incidence of fracture and local failure and associated risk factors after stereotactic body radiation therapy (SBRT) for long bone metastases. METHODS AND MATERIALS: Data from 111 patients with 114 metastases in the femur, humerus, and tibia treated with SBRT in 7 international centers between October 2011 and February 2021 were retrospectively reviewed and analyzed using a competing risk regression model. RESULTS: The median follow-up was 21 months (range, 6-91 months). All but 1 patient had a Karnofsky performance status ≥70. There were 84 femur (73.7%), 26 humerus (22.8%), and 4 tibia (3.5%) metastases from prostate (45 [39.5%]), breast (22 [19.3%]), lung (15 [13.2%]), kidney (13 [11.4%]), and other (19 [16.6%]) malignancies. Oligometastases accounted for 74.8% of metastases and 28.1% were osteolytic. The most common total doses were 30 to 50 Gy in 5 daily fractions (50.9%). Eight fractures (5 in the femur, 2 in the tibia, and 1 in the humerus) were observed with a median time to fracture of 12 months (range, 0.8-33 months). In 6 out of 8 patients, fracture was not associated with local failure. The cumulative incidence of fracture was 3.5%, 6.1%, and 9.8% at 1, 2, and 3 years, respectively. The cumulative incidence of local failure (9/110 metastases with imaging follow-up) was 5.7%, 7.2%, and 13.5% at 1, 2, and 3 years, respectively. On multivariate analysis, extraosseous disease extension was significantly associated with fracture (P = .001; subhazard ratio, 10.8; 95% confidence interval, 2.8-41.9) and local failure (P = .02; subhazard ratio, 7.9; 95% confidence interval, 1.4-44.7). CONCLUSIONS: SBRT for metastases in long bones achieved high rates of durable local metastasis control without an increased risk of fracture. Similar to spine SBRT, patients with extraosseous disease extension are at higher risk of local failure and fracture.

Radiation Therapy in Oligometastatic Prostate Cancer.

Prostate cancer ranges from localized, low risk to metastatic, morbid disease. Although radiation therapy (RT) is commonly incorporated in the treatment of early disease or for palliation of symptomatic lesions, its role in extending survival in metastatic disease is less well-established. Here, we review the available evidence surrounding localized RT in the presence of oligometastatic disease and metastasis-directed therapy in both hormone-sensitive and hormone-resistant prostate cancer. We further outline potential future incorporation of RT as an immune-sensitizing therapy and the importance of highly sensitive imaging modalities in considering RT in metastatic disease.

Intensity Modulated Proton Therapy for Bilateral Breast or Chest Wall and Comprehensive Nodal Irradiation for Synchronous Bilateral Breast Cancer: Initial Clinical Experience and Dosimetric Comparison.

Purpose: Synchronous bilateral breast cancer (SBBC) poses distinct challenges for radiation therapy planning. We report our proton therapy experience in treating patients with SBBC. We also provide a dosimetric comparison of intensity modulated proton therapy (IMPT) versus photon therapy. Methods and Materials: Patients with SBBC who received IMPT at our institution were retrospectively analyzed. The clinical target volume (CTV) included the breast or chest wall and comprehensive regional lymph nodes, including axilla, supraclavicular fossa, and the internal mammary chain. Intensity modulated proton therapy and volumetric modulated arc therapy (VMAT) plans were generated with the goal that 90% of the CTV would recieve at least 90% of the prescription dose (D90>=90%). Comparisons between modalities were made using the Wilcoxon signed rank test. Physician-reported acute toxic effects and photography were collected at baseline, end of treatment, and each follow-up visit. Results: Between 2015 and 2018, 11 patients with SBBC were treated with IMPT. The prescription was 50 Gy in 25 fractions. The median CTV D90 was 99.9% for IMPT and 97.6% for VMAT (P = .001). The mean heart dose was 0.7 Gy versus 7.2 Gy (P = .001), the total lung mean dose was 7.8 Gy versus 17.3 Gy (P = .001), and the total lung volume recieving 20 Gy was 13.0% versus 27.4% (P = .001). The most common acute toxic effects were dermatitis (mostly grade 1-2 with 1 case of grade 3) and grade 1 to 2 fatigue. The most common toxic effects at the last-follow up (median, 32 months) were grade 1 skin hyperpigmentation, superficial fibrosis, and extremity lymphedema. No nondermatologic or nonfatigue adverse events of grade >1 were recorded. Conclusions: Bilateral breast and/or chest wall and comprehensive nodal IMPT is technically feasible and associated with low rates of severe acute toxic effects. Treatment with IMPT offered improved target coverage and normal-tissue sparing compared with photon therapy. Long-term follow-up is ongoing to assess efficacy and toxic effects.