Anesthetic Oxygen Use and Sex Are Critical Factors in the FLASH Sparing Effect.

Purpose: Ultra High Dose-Rate (UHDR) radiation has been reported to spare normal tissue, compared with Conventional Dose-Rate (CDR) radiation. However, important work remains to be done to improve the reproducibility of the FLASH effect. A better understanding of the biologic factors that modulate the FLASH effect may shed light on the mechanism of FLASH sparing. Here, we evaluated whether sex and/or the use of 100% oxygen as a carrier gas during irradiation contribute to the variability of the FLASH effect. Methods and Materials: C57BL/6 mice (24 male, 24 female) were anesthetized using isoflurane mixed with either room air or 100% oxygen. Subsequently, the mice received 27 Gy of either 9 MeV electron UHDR or CDR to a 1.6 cm2 diameter area of the right leg skin using the Mobetron linear accelerator. The primary postradiation endpoint was time to full thickness skin ulceration. In a separate cohort of mice (4 male, 4 female), skin oxygenation was measured using PdG4 Oxyphor under identical anesthesia conditions. Results: Neither supplemental oxygen nor sex affected time to ulceration in CDR irradiated mice. In the UHDR group, skin damage occured earlier in male and female mice that received 100% oxygen compared room air and female mice ulcerated sooner than male mice. However, there was no significant difference in time to ulceration between male and female UHDR mice that received room air. Oxygen measurements showed that tissue oxygenation was significantly higher when using 100% oxygen as the anesthesia carrier gas than when using room air, and female mice showed higher levels of tissue oxygenation than male mice under 100% oxygen. Conclusions: The skin FLASH sparing effect is significantly reduced when using oxygen during anesthesia rather than room air. FLASH sparing was also reduced in female mice compared to male mice. Both tissue oxygenation and sex are likely sources of variability in UHDR studies. These results suggest an oxygen-based mechanism for FLASH, as well as a key role for sex in the FLASH skin sparing effect.

Association of differential censoring with survival and suboptimal control arms among oncology clinical trials.

Differential censoring (DC), referring to censoring imbalance between treatment arms, may bias the interpretation of survival outcomes in clinical trials. In 146 phase 3 oncology trials with statistically significant time-to-event surrogate primary endpoints (PEPs), we evaluated the association between DC in the surrogate PEP, control arm adequacy, and the subsequent statistical significance of OS results. Twenty-four (16%) trials exhibited DC favoring the control arm (ConDC), while 15 (10%) exhibited experimental arm DC (ExpDC). Positive OS was more common in ConDC trials (63%) than trials without DC (37%) or with ExpDC (47%; odds ratio [OR] 2.64, 95% CI 1.10-7.20; P=.04). ConDC trials more frequently used suboptimal control arms (46%) compared to 20% without DC and 13% with ExpDC (OR 3.60, 95% CI 1.29-10.0; P=.007). The presence of ConDC in trials with surrogate PEPs, especially in those with OS conversion, may indicate an inadequate control arm and should be examined and explained.

Can I Leave? Perspectives on Parental Leave and Parenthood in Medical Training Among Program Directors and Trainees in Oncologic Specialties.

Purpose: Peak fertility commonly occurs during medical training, and delaying parenthood can complicate pregnancies. Trainee parental leave policies are varied and lack transparency. Research on the impacts of parenthood on trainee education is limited. Methods: A Qualtrics-based survey was distributed via e-mail/social media to program directors (PDs) within oncologic specialties with a request to forward a parallel survey to trainees. Questions assessed awareness of parental leave policies, supportiveness of parenthood, and impacts on trainee education. Statistical analyses included descriptive frequencies and bivariable comparisons by key groups. Results: A total of 195 PDs and 286 trainees responded. Twelve percent and 29% of PDs were unsure of maternity/paternity leave options, respectively. PDs felt they were more supportive of trainee parenthood than trainees perceived they were. Thirty-nine percent of nonparent trainees (NPTs) would have children already if not in medicine, and >80% of women trainees were concerned about declining fertility. Perceived impacts of parenthood on trainee overall education and academic productivity were more negative for women trainees when rated by PDs and NPTs; however, men/women parents self-reported equal impacts. Leave burden was perceived as higher for women trainees. Conclusions: A significant portion of PDs lack awareness of parental leave policies, highlighting needs for increased transparency. Trainees' perception of PD support for parenthood is less than PD self-reported support. Alongside significant rates of delayed parenthood and fertility concerns, this poses a problem for trainees seeking to start a family, particularly women who are perceived more negatively. Further work is needed to create a supportive culture for trainee parenthood.

Disparities in outcomes and access to therapy options in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) disproportionately impacts racial and ethnic minorities and patients with lower socioeconomic status. These social determinants of health (SDH) lead to disparities in access to care and outcomes. We aim to understand the relationship between SDH and survival and locoregional treatment options in HCC. METHODS: Using the National Cancer Database, we evaluated survival and access locoregional treatments including non-transplant surgery, liver transplant (LT), and liver-directed radiation therapy (LDRT) in patients with HCC diagnosed between 2004 and 2017. Variables including clinical stage, age, sex, race, income, rurality, year of diagnosis, facility type (FT), Charlson-Deyo score (CD), and insurance were evaluated. Cox proportional hazards multivariable regression and dominance analyses were used for analyses. RESULTS: In total, 140 340 patients were included. Worse survival was seen with advanced stage, older age, Black race, rurality, public insurance, treatment at a nonacademic center, and lower income. The top predictors for survival included stage, age, and income. Completion of non-transplant surgery was best predicted by stage, FT, and insurance type, whereas LT was predicted by age, year of diagnosis, and CD score. LDRT utilization was most associated with year of diagnosis, FT, and CD score. CONCLUSION: For patients with HCC, survival was predicted primarily by stage, age, and income. The primary sociodemographic factors associated with access to surgical treatments, in addition to FT, were insurance and income, highlighting the financial burdens of health care. Work is needed to address disparities in access to care, including improved insurance access, addressing financial inequities and financial toxicities of treatments, and equalizing care opportunities in community centers.

Anesthetic oxygen use and sex are critical factors in the FLASH sparing effect.

Introduction: Ultra-high dose-rate (UHDR) radiation has been reported to spare normal tissue compared to conventional dose-rate (CDR) radiation. However, reproducibility of the FLASH effect remains challenging due to varying dose ranges, radiation beam structure, and in-vivo endpoints. A better understanding of these inconsistencies may shed light on the mechanism of FLASH sparing. Here, we evaluate whether sex and/or use of 100% oxygen as carrier gas during irradiation contribute to the variability of the FLASH effect. Methods: C57BL/6 mice (24 male, 24 female) were anesthetized using isoflurane mixed with either room air or 100% oxygen. Subsequently, the mice received 27 Gy of either 9 MeV electron UHDR or CDR to a 1.6 cm2 diameter area of the right leg skin using the Mobetron linear accelerator. The primary post-radiation endpoint was time to full thickness skin ulceration. In a separate cohort of mice (4 male, 4 female) skin oxygenation was measured using PdG4 Oxyphor under identical anesthesia conditions. Results: In the UHDR group, time to ulceration was significantly shorter in mice that received 100% oxygen compared to room air, and amongst them female mice ulcerated sooner compared to males. However, no significant difference was observed between male and female UHDR mice that received room air. Oxygen measurements showed significantly higher tissue oxygenation using 100% oxygen as the anesthesia carrier gas compared to room air, and female mice showed higher levels of tissue oxygenation compared to males under 100% oxygen. Conclusion: The FLASH sparing effect is significantly reduced using oxygen during anesthesia compared to room air. The FLASH sparing was significantly lower in female mice compared to males. Both tissue oxygenation and sex are likely sources of variability in UHDR studies. These results suggest an oxygen-based mechanism for FLASH, as well as a key role for sex in the FLASH skin sparing effect.

Retrospective evidence for pediatric benefit of U.S. assault weapons ban as rationale for implementing an even more effective ban.

BACKGROUND: With data available since 1981, firearm death rates in American children and adolescents can be evaluated for trends during the 13 years before, the decade of, and during 16 years since the United States (U.S.) 1994-2004 Federal Assault Weapons Ban (FAWB). METHODS: National and regional firearm mortality trends in the U.S. during 1981-2020 were assessed with joinpoint regression applied to Centers for Disease Control and Prevention data. RESULTS: After increasing exponentially before the FAWB, the national firearm death rate in 0-14 year-olds promptly reversed course and declined throughout the FAWB and then reversed again after the FAWB and resumed an exponential increase (all phases p<0.001). The reduction in firearm death rate occurred within 1-3 years of the start of the FAWB, in both sexes, in all four census regions of the U.S., and in all four major race/ethnicity subgroups, especially non-Hispanic blacks. No other form of violence in 0-14 year-olds had this temporal relationship with the FAWB. The firearm mortality reduction during the FAWB is strongly-highly correlated with the concomitant reduction in handgun manufacturing in 91 % of 24 sex, race/ethnicity and region subsets analyzed, These FAWB-related trends were also apparent in older adolescents and young adults and less so in older persons. CONCLUSIONS: Firearm death rates in 0-14 year-olds before, during, and after the FAWB, and no other type of injury, implicate the FAWB as having had a beneficial effect. Legislation to mitigate firearm mortality and injury inclusive of a FAWB should be especially beneficial to children and young adolescents, and regardless of sex, race/ethnicity or region in the U.S.

Selection and Prejudice: Addressing Clinical Trial Disparities With a Review of Current Shortcomings and Future Directions.

Growing evidence has demonstrated significant, persistent, and widespread disparities in cancer clinical trial enrollment across myriad disease sites and target populations. Although mechanisms underlying such disparities are complex and multifactorial, clinical trial eligibility criteria may serve as a key structural barrier to equitable and diverse trial enrollment. In this review, we provide an overview of the data describing historical and current disparities in cancer clinical trial enrollment and subsequently describe several patient-, institution-, and trial-related factors which appear to be key drivers of enrollment inequity, with specific discussion regarding the impact of eligibility criteria. We further describe the landscape of ongoing professional efforts aimed at eliminating clinical trial disparities through various medical, professional, and advocacy groups. The review concludes with a practical discussion of how modernization of eligibility criteria in clinical trials may decrease or eliminate trial disparities, including specific actionable recommendations aimed at improving the quality of future eligibility criteria.

Effects of UHDR and Conventional Irradiation on Behavioral and Cognitive Performance and the Percentage of Ly6G+ CD45+ Cells in the Hippocampus.

We assessed the effects of conventional and ultra-high dose rate (UHDR) electron irradiation on behavioral and cognitive performance one month following exposure and assessed whether these effects were associated with alterations in the number of immune cells in the hippocampus using flow cytometry. Two-month-old female and male C57BL/6J mice received whole-brain conventional or UHDR irradiation. UHDR mice were irradiated with 9 MeV electrons, delivered by the Linac-based/modified beam control. The mice were irradiated or sham-irradiated at Dartmouth, the following week shipped to OHSU, and behaviorally and cognitively tested between 27 and 41 days after exposure. Conventional- and UHDR-irradiated mice showed impaired novel object recognition. During fear learning, conventional- and UHDR-irradiated mice moved less during the inter-stimulus interval (ISI) and UHDR-irradiated mice also moved less during the baseline period (prior to the first tone). In irradiated mice, reduced activity levels were also seen in the home cage: conventional- and UHDR-irradiated mice moved less during the light period and UHDR-irradiated mice moved less during the dark period. Following behavioral and cognitive testing, infiltrating immune cells in the hippocampus were analyzed by flow cytometry. The percentage of Ly6G+ CD45+ cells in the hippocampus was lower in conventional- and UHDR-irradiated than sham-irradiated mice, suggesting that neutrophils might be particularly sensitive to radiation. The percentage of Ly6G+ CD45+ cells in the hippocampus was positively correlated with the time spent exploring the novel object in the object recognition test. Under the experimental conditions used, cognitive injury was comparable in conventional and UHDR mice. However, the percentage of CD45+ CD11b+ Ly6+ and CD45+ CD11b+ Ly6G- cells in the hippocampus cells in the hippocampus was altered in conventional- but not UHDR-irradiated mice and the reduced percentage of Ly6G+ CD45+ cells in the hippocampus might mediate some of the detrimental radiation-induced cognitive effects.

Incidence of Primary End Point Changes Among Active Cancer Phase 3 Randomized Clinical Trials.

Importance: Primary end point (PEP) changes to an active clinical trial raise questions regarding trial quality and the risk of outcome reporting bias. It is unknown how the frequency and transparency of the reported changes depend on reporting method and whether the PEP changes are associated with trial positivity (ie, the trial met the prespecified statistical threshold for PEP positivity). Objectives: To assess the frequency of reported PEP changes in oncology randomized clinical trials (RCTs) and whether these changes are associated with trial positivity. Design, Setting, and Participants: This cross-sectional study used publicly available data for complete oncology phase 3 RCTs registered in ClinicalTrials.gov from inception through February 2020. Main Outcomes and Measures: The main outcome was change between the initial PEP and the final reported PEP, assessed using 3 methods: (1) history of tracked changes on ClinicalTrials.gov, (2) self-reported changes noted in the article, and (3) changes reported within the protocol, including all available protocol documents. Logistic regression analyses were performed to evaluate whether PEP changes were associated with US Food and Drug Administration approval or trial positivity. Results: Of 755 included trials, 145 (19.2%) had PEP changes found by at least 1 of the 3 detection methods. Of the 145 trials with PEP changes, 102 (70.3%) did not have PEP changes disclosed within the manuscript. There was significant variability in rates of PEP detection by each method (χ2 = 72.1; P < .001). Across all methods, PEP changes were detected at higher rates when multiple versions of the protocol (47 of 148 [31.8%]) were available compared with 1 version (22 of 134 [16.4%]) or no protocol (76 of 473 [16.1%]) (χ2 = 18.7; P < .001). Multivariable analysis demonstrated that PEP changes were associated with trial positivity (odds ratio, 1.86; 95% CI, 1.25-2.82; P = .003). Conclusions and Relevance: This cross-sectional study revealed substantial rates of PEP changes among active RCTs; PEP changes were markedly underreported in published articles and mostly occurred after reported study completion dates. Significant discrepancies in the rate of detected PEP changes call into question the role of increased protocol transparency and completeness in identifying key changes occurring in active trials.

Phase 2 study of preoperative chemotherapy with nab-paclitaxel and gemcitabine followed by chemoradiation for borderline resectable or node-positive pancreatic ductal adenocarcinoma.

BACKGROUND: Neoadjuvant treatment with nab-paclitaxel and gemcitabine for potentially operable pancreatic adenocarcinoma has not been well studied in a prospective interventional trial and could down-stage tumors to achieve negative surgical margins. METHODS: A single-arm, open-label phase 2 trial (NCT02427841) enrolled patients with pancreatic adenocarcinoma deemed to be borderline resectable or clinically node-positive from March 17, 2016 to October 5, 2019. Patients received preoperative gemcitabine 1000 mg/m2 and nab-paclitaxel 125 mg/m2 on Days 1, 8, 15, every 28 days for two cycles followed by chemoradiation with 50.4 Gy intensity-modulated radiation over 28 fractions with concurrent fluoropyrimidine chemotherapy. After definitive resection, patients received four additional cycles of gemcitabine and nab-paclitaxel. The primary endpoint was R0 resection rate. Other endpoints included treatment completion rate, resection rate, radiographic response rate, survival, and adverse events. RESULTS: Nineteen patients were enrolled, with the majority having head of pancreas primary tumors, both arterial and venous vasculature involvement, and clinically positive nodes on imaging. Among them, 11 (58%) underwent definitive resection and eight of 19 (42%) achieved R0 resection. Disease progression and functional decline were primary reasons for deferring surgical resection after neoadjuvant treatment. Pathologic near-complete response was observed in two of 11 (18%) resection specimens. Among the 19 patients, the 12-month progression-free survival was 58%, and 12-month overall survival was 79%. Common adverse events were alopecia, nausea, vomiting, fatigue, myalgia, peripheral neuropathy, rash, and neutropenia. CONCLUSION: Gemcitabine and nab-paclitaxel followed by long-course chemoradiation represents a feasible neoadjuvant treatment strategy for borderline resectable or node-positive pancreatic cancer.

Consensus Quality Measures and Dose Constraints for Lung Cancer From the Veterans Affairs Radiation Oncology Quality Surveillance Program and ASTRO Expert Panel.

PURPOSE: For patients with lung cancer, it is critical to provide evidence-based radiation therapy to ensure high-quality care. The US Department of Veterans Affairs (VA) National Radiation Oncology Program partnered with the American Society for Radiation Oncology (ASTRO) as part of the VA Radiation Oncology Quality Surveillance to develop lung cancer quality metrics and assess quality of care as a pilot program in 2016. This article presents recently updated consensus quality measures and dose-volume histogram (DVH) constraints. METHODS AND MATERIALS: A series of measures and performance standards were reviewed and developed by a Blue-Ribbon Panel of lung cancer experts in conjunction with ASTRO in 2022. As part of this initiative, quality, surveillance, and aspirational metrics were developed for (1) initial consultation and workup; (2) simulation, treatment planning, and treatment delivery; and (3) follow-up. The DVH metrics for target and organ-at-risk treatment planning dose constraints were also reviewed and defined. RESULTS: Altogether, a total of 19 lung cancer quality metrics were developed. There were 121 DVH constraints developed for various fractionation regimens, including ultrahypofractionated (1, 3, 4, or 5 fractions), hypofractionated (10 and 15 fractionations), and conventional fractionation (30-35 fractions). CONCLUSIONS: The devised measures will be implemented for quality surveillance for veterans both inside and outside of the VA system and will provide a resource for lung cancer-specific quality metrics. The recommended DVH constraints serve as a unique, comprehensive resource for evidence- and expert consensus-based constraints across multiple fractionation schemas.

Pilot Study Exploring the Feasibility of Incorporating Radiation Oncology Into Pre-existing Early Pathway Programs for Diverse Premedical Students.

PURPOSE: Many medical schools in the United States have affiliated pathway, preparatory, and/or prematriculation programs that enroll a high percentage of students historically underrepresented in medicine (URiM). The purpose of this pilot study was to better characterize exposures to radiation oncology (RO) among students in these programs and determine the feasibility of incorporating a radiation oncologist within their pre-existing format if nonexistent. METHODS AND MATERIALS: During the summers of 2021 and 2022, a radiation oncologist gave a presentation about basic principles of cancer care to 18 unique student groups in 12 premedical programs affiliated with 8 medical schools. Participating students were asked to complete an anonymous postpresentation questionnaire. Descriptive statistics are reported. RESULTS: A total of 467 students attended the presentations, and 241 completed the questionnaire (response rate 52.0%). The majority of participants reported being female (63.5%), URiM (66.4%), and low income (57.3%). Students were less likely to report previous teaching from a radiation oncologist (11.2%) than a surgical (17.0%) or medical oncologist (18.3%). Prior clinical shadowing with a radiation oncologist (2.9%) was also less likely than shadowing a surgical oncologist (5.0%), medical oncologist (6.6%), or any other physician (53.1%). Students were also less likely to previously believe that radiation could cure cancer (65.8%) compared with surgery (74.9%) or chemotherapy (89.3%). After the presentation, 168 students (69.7%) were more interested in a career in RO, and 211 students (87.6%) responded that the presentation was either quite or extremely valuable (median Likert-type score, 5; interquartile range, 4-5). CONCLUSIONS: Many of the students in premedical programs lack prior exposure to RO or knowledge of multidisciplinary cancer care, which was ameliorated by a simple yet effective presentation across a variety of different types of programs in this study. Longitudinal assessment of different types of educational initiatives and students' ultimate career trajectory will help optimize future RO initiatives among premedical URiM students.

Impact of a Virtual Introduction to Radiation Oncology Presentation on Stimulating Interest in the Specialty Among Diverse Medical Students at Multiple Institutions.

PURPOSE: Many US medical students lack access to radiation oncology (RO). The authors' hypothesis was that a virtual, cross-institutional presentation introducing students to a career in RO would be valuable in exposing students to RO who are less likely to access it otherwise and would increase students' interest in a career in RO regardless of their gender, race, or ethnicity. METHODS: A 1-hour, live, virtual, extracurricular presentation was offered to deans of US medical schools lacking affiliated RO departments and/or having high enrollments of students underrepresented in medicine (UIM) and also student groups composed primarily of UIM students. Presentations were given individually to each school by a single radiation oncologist. An electronic survey captured data from participating students. RESULTS: One hundred ninety-seven students from 13 institutions attended presentations; 114 students responded to the survey (response rate, 58%). Ninety-two students (81%) were aware of the specialty of RO before the presentation; however, UIM students were significantly less likely to be aware of RO than all others (69% versus 87%, P = .05). Only 19 students (17%) reported previously hearing presentations from radiation oncologist (29% among second- to fourth-year students versus 9% among first-year students, P = .01). Ninety-eight students (86%) expressed more interest in pursuing a career in RO after the presentation. There was no significant difference in interest in RO for any demographic subgroups. CONCLUSIONS: Virtual RO exposure was feasible to deliver to students less likely to be exposed otherwise and successfully stimulated interest in the specialty regardless of students' gender, race, or ethnicity.

The multidisciplinary management of cholangiocarcinoma.

Cholangiocarcinoma is a lethal malignancy of the biliary epithelium that can arise anywhere along the biliary tract. Surgical resection confers the greatest likelihood of long-term survivability. However, its insidious onset, difficult diagnostics, and resultant advanced presentation render the majority of patients unresectable, highlighting the importance of early detection with novel biomarkers. Developing liver-directed therapies and emerging targeted therapeutics may offer improved survivability for patients with unresectable or advanced disease. In this article, the authors review the current multidisciplinary standards of care in resectable and unresectable cholangiocarcinoma, with an emphasis on novel biomarkers for early detection and nonsurgical locoregional therapy options.

Radiotherapy reimagined: Integrating nanomedicines into radiotherapy clinical trials.

Radioenhancing nanoparticles (NPs) are being evaluated in ongoing clinical trials for various cancers including head and neck, lung, esophagus, pancreas, prostate, and soft tissue sarcoma. Supported by decades of preclinical investigation and recent randomized trial data establishing clinical activity, these agents are poised to influence future multimodality treatment paradigms involving radiotherapy. Although the physical interactions between NPs and ionizing radiation are well characterized, less is known about how these agents modify the tumor microenvironment, particularly regarding tumor immunogenicity. In this review, we describe the key multidisciplinary considerations related to radiation, surgery, immunology, and pathology for designing radioenhancing NP clinical trials. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Association of fall rate and functional status by APOE genotype in cancer survivors after exercise intervention.

PURPOSE/OBJECTIVES: Cancer treatment survivors often report impaired functioning and increased falls. Not all survivors experience the same symptom burden, suggesting individual susceptibilities. APOE genotype is a potential genetic risk factor for cancer treatment related side effects. Lifestyle factors such as physical activity can mitigate the effect of APOE genotype on measures of clinical interest in individuals without a history of cancer. We tested the hypothesis that APOE genotype influences cancer treatment related side effects and symptoms as well as response to exercise intervention. MATERIALS AND METHODS: Data from a subsample of a study of fall prevention exercise in post-treatment female cancer survivors aged 50-75 years old (https://clinicaltrials.gov NCT01635413) were used to conduct a secondary data analysis. ApoE genotype was determined by serum sampling. Physical functioning, frequency of falls, and symptom burden were assessed using survey instruments. RESULTS: Data from 126 female cancer survivors a median of 49 months out from cancer diagnosis were analyzed. ApoE4 carriers trended toward a higher fall rate at baseline (p = 0.059), but after exercise intervention had a fall rate lower than E4 non-carriers both immediately after structured intervention (p = 0.013) and after 6 months of follow up (p = 0.002). E2 carriers did not show improved measures of depressive symptoms and self-report disability after exercise intervention. E3 homozygotes showed increased self report physical activity after the 6 month exercise intervention, but E4 and E2 carriers did not. CONCLUSIONS: APOE genotype may modulate cancer treatment related side effects and symptoms and response to exercise intervention.