Peterson, Christine B.

PURPOSE The ECOG-ACRIN E3311 phase II trial demonstrated outstanding disease control (90.6% 54-month progression-free survival) after transoral surgery (TOS) with de-escalated, risk-based postoperative management in resectable human papillomavirus–associated oropharyngeal cancer. The goal of de-escalation was functional preservation. The objective of this work was to evaluate clinician-graded modified barium swallow (MBS) studies from E3311 over time and across arms for (1) aspiration and high-grade pharyngeal residue rates, (2) differences in swallow safety and efficiency, and (3) accuracy of site clinicians reporting against central MBS review. METHODS Eight hundred eighty-five MBS studies were performed on 314 patients from 50 of 59 sites at baseline, post-TOS, and 6 and 24 months postradiotherapy (RT). Swallow outcomes (aspiration, high-grade residue) were recorded by site clinicians. A subset of 414 MBS studies was centrally graded using penetration-aspiration scale scores and the Dynamic Imaging Grade of Swallowing Toxicity (DIGEST) scale. RESULTS Aspiration, residue, and dysphagia rates significantly increased from baseline to post-TOS ( P < .01) and then decreased modestly at 6 and 24 months. At 6 months, swallow outcomes favored the 50- versus 60-Gy arm, with significantly lower aspiration and high-grade dysphagia rates, but this difference was not maintained at 24 months. MBS results reported by site clinicians demonstrated substantial agreement with those assessed by the central laboratory (PABAK, 0.75-0.84; P < .01). CONCLUSION Swallowing worsened after TOS but improved by 6 and 24 months despite adjuvant therapy. De-escalated adjuvant RT at 50 Gy reduced acute aspiration. Site-reported MBS metrics strongly aligned with DIGEST, showing potential as an accessible metric in cooperative group settings.

Abstract Background A passive dosimeter framework for the measurement of dose in carbon ion beams has yet to be characterized or implemented for regular use. Purpose This work determined the dose calculation correction factors for absorbed dose in thermoluminescent dosimeters (TLDs) in a therapeutic carbon ion beam. TLD could be a useful tool for remote audits, particularly in the context of clinical trials as new protocols are developed for carbon ion radiotherapy. Methods TLD‐100 were irradiated in a carbon ion beam at the Centro Nazionale di Adroterapia Oncologica (CNAO) in Pavia, Italy. The dose correction factors for linearity, fading, and beam quality were characterized. Fading was characterized from 5 to 100 days post‐irradiation. For linearity, the TLDs were irradiated to absorbed doses ranging from 1 to 15 Gy in both the entrance of a high‐energy pristine carbon ion peak and the center of a 2 cm spread‐out Bragg peak. For beam quality, the TLD was irradiated to the same absorbed dose (3 Gy) in several pristine carbon ion Bragg peaks, as well as in several spread‐out Bragg peaks. Each correction factor was calculated and compared to photon correction factors. The correction factors were also compared between high and low dose‐averaged linear energy transfer (LET D ) in the carbon ion beams. The absorbed dose was compared between ion chamber and TLD‐100 in the several tissue substitute phantom materials, applying the carbon ion TLD correction factors. Results There was no statistically significant difference in the TLD fading correction factor between photons, low LET D carbon ion beams, or high LET D carbon ion beams. The TLD linearity correction factor did differ between photons, low LET D carbon ions, and high LET D carbon ions. The beam quality correction factor was large and changed linearly with LET D . The overall uncertainty of the carbon ion absorbed dose calculation was 3.9% at the one‐sigma level, driven largely by a 3.5% uncertainty in the beam quality correction. TLD measurements were within 1.2% of ion chamber measurements in the phantom material for polyethylene, solid water (Gammex and Sun Nuclear), acrylic, blue water, and techtron HPV. TLD measurements in balsa wood were within 3.0% and cork was 6.6% low compared to ion chamber. Conclusion TLD‐100 can be used for passive dosimetry in a therapeutic carbon ion beam. Importantly, the linearity and beam quality correction factors are both different from photon therapy, and dependent on LET D of the carbon ion beam. This opens the possibility of TLD use for carbon ion output audits, phantom audits, and in vivo dose measurements, but may be subject to more complicated management and slightly larger uncertainties than are achieved in photon beams.

Abstract Objective . This study characterized optically-stimulated luminescent dosimeter (OSLD) nanoDots for use in a therapeutic carbon beam using the Imaging and Radiation Oncology Core (IROC) framework for remote output verification. Approach . The absorbed dose correction factors for OSLD (fading, linearity, beam quality, angularity, and depletion), as defined by AAPM TG 191, were characterized for carbon beams. For the various correction factors, the effect of linear energy transfer (LET) was examined by characterizing in both a low and high LET setting. Main results . Fading was not statistically different between reference photons and carbon, nor between low and high LET beams; thus, the standard IROC-defined exponential function could be used to characterize fading. Dose linearity was characterized with a linear fit; while low and high LET carbon linearity was different, these differences were small and could be rolled into the uncertainty budget if using a single linearity correction. A linear fit between beam quality and dose-averaged LET was determined. The OSLD response at various angles of incidence was not statistically different, thus a correction factor need not be applied. There was a difference in depletion between low and high LET irradiations in a primary carbon beam, but this difference was small over the standard five readings. The largest uncertainty associated with the use of OSLDs in carbon was because of the k Q correction factor, with an uncertainty of 6.0%. The overall uncertainty budget was 6.3% for standard irradiation conditions. Significance . OSLD nanoDot response was characterized in a therapeutic carbon beam. The uncertainty was larger than for traditional photon applications. These findings enable the use of OSLDs for carbon absorbed dose measurements, but with less accuracy than conventional OSLD audit programs.

AbstractPurposeAs carbon ion radiotherapy increases in use, there are limited phantom materials for heterogeneous or anthropomorphic phantom measurements. This work characterized the radiological clinical equivalence of several phantom materials in a therapeutic carbon ion beam.MethodsEight materials were tested for radiological material‐equivalence in a carbon ion beam. The materials were computed tomography (CT)‐scanned to obtain Hounsfield unit (HU) values, then irradiated in a monoenergetic carbon ion beam to determine relative linear stopping power (RLSP). The corresponding HU and RLSP for each phantom material were compared to clinical carbon ion calibration curves. For absorbed dose comparison, ion chamber measurements were made in the center of a carbon ion spread‐out Bragg peak (SOBP) in water and in the phantom material, evaluating whether the material perturbed the absorbed dose measurement beyond what was predicted by the HU‐RLSP relationship.ResultsPolyethylene, solid water (Gammex and Sun Nuclear), Blue Water (Standard Imaging), and Techtron HPV had measured RLSP values that agreed within ±4.2% of RLSP values predicted by the clinical calibration curve. Measured RLSP for acrylic was 7.2% different from predicted. The agreement for balsa wood and cork varied between samples. Ion chamber measurements in the phantom materials were within 0.1% of ion chamber measurements in water for most materials (solid water, Blue Water, polyethylene, and acrylic), and within 1.9% for the rest of the materials (balsa wood, cork, and Techtron HPV).ConclusionsSeveral phantom materials (Blue Water, polyethylene, solid water [Gammex and Sun Nuclear], and Techtron HPV) are suitable for heterogeneous phantom measurements for carbon ion therapy. Low density materials should be carefully characterized due to inconsistencies between samples.

Importance Requiring personalized genetic counseling may introduce barriers to cancer risk assessment, but it is unknown whether omitting counseling could increase distress. Objective To assess whether omitting pretest and/or posttest genetic counseling would increase distress during remote testing. Design, Setting, and Participants Making Genetic Testing Accessible (MAGENTA) was a 4-arm, randomized noninferiority trial testing the effects of individualized pretest and/or posttest genetic counseling on participant distress 3 and 12 months posttest. Participants were recruited via social and traditional media, and enrollment occurred between April 27, 2017, and September 29, 2020. Participants were women aged 30 years or older, English-speaking, US residents, and had access to the internet and a health care professional. Previous cancer genetic testing or counseling was exclusionary. In the family history cohort, participants had a personal or family history of breast or ovarian cancer. In the familial pathogenic variant (PV) cohort, participants reported 1 biological relative with a PV in an actionable cancer susceptibility gene. Data analysis was performed between December 13, 2020, and May 31, 2023. Intervention Participants completed baseline questionnaires, watched an educational video, and were randomized to 1 of 4 arms: the control arm with pretest and/or posttest genetic counseling, or 1 of 3 study arms without pretest and posttest counseling. Genetic counseling was provided by phone appointments and testing was done using home-delivered saliva kits. Main Outcomes and Measures The primary outcome was participant distress measured by the Impact of Event Scale 3 months after receiving the results. Secondary outcomes included completion of testing, anxiety, depression, and decisional regret. Results A total of 3839 women (median age, 44 years [range 22-91 years]), most of whom were non-Hispanic White and college educated, were randomized, 3125 in the family history and 714 in the familial PV cohorts. In the primary analysis in the family history cohort, all experimental arms were noninferior for distress at 3 months. There were no statistically significant differences in anxiety, depression, or decisional regret at 3 months. The highest completion rates were seen in the 2 arms without pretest counseling. Conclusions and Relevance In the MAGENTA clinical trial, omitting individualized pretest counseling for all participants and posttest counseling for those without PV during remote genetic testing was not inferior with regard to posttest distress, providing an alternative care model for genetic risk assessment. Trial Registration ClinicalTrials.gov Identifier: NCT02993068

AbstractMeta‐analysis allows researchers to combine evidence from multiple studies, making it a powerful tool for synthesizing information on the safety profiles of new medical interventions. There is a critical need to identify subgroups at high risk of experiencing treatment‐related toxicities. However, this remains quite challenging from a statistical perspective as there are a variety of clinical risk factors that may be relevant for different types of adverse events, and adverse events of interest may be rare or incompletely reported. We frame this challenge as a variable selection problem and propose a Bayesian hierarchical model which incorporates a horseshoe prior on the interaction terms to identify high‐risk groups. Our proposed model is motivated by a meta‐analysis of adverse events in cancer immunotherapy, and our results uncover key factors driving the risk of specific types of treatment‐related adverse events.

Abstract Microdosimetry is an important tool for assessing energy deposition distributions from ionizing radiation at cellular and cellular nucleus scales. It has served as an input parameter for multiple common mathematical models, including evaluation of relative biological effectiveness (RBE) of carbon ion therapy. The most common detector used for microdosimetry is the tissue-equivalent proportional counter (TEPC). Although it is widely applied, TEPC has various inherent uncertainties. Therefore, this work quantified the magnitude of TEPC measurement uncertainties and their impact on RBE estimates for therapeutic carbon beams. Microdosimetric spectra and frequency-, dose-, and saturation-corrected dose-mean lineal energy (****) were calculated using the Monte Carlo toolkit Geant4 for five monoenergetic and three spread-out Bragg peak carbon beams in water at every millimeter along the central beam axis. We simulated the following influences on these spectra from eight sources of uncertainty: wall effects, pulse pile-up, electronics, gas pressure, W-value, gain instability, low energy cut-off, and counting statistics. Statistic uncertainty was quantified as the standard deviation of perturbed values for each source. Bias was quantified as the difference between default lineal energy values and the mean of perturbed values for each systematic source. Uncertainties were propagated to RBE using the modified microdosimetric kinetic model (MKM). Variance introduced by statistic sources in y ¯ F and y ¯ D averaged 3.8% and 3.4%, respectively, and 1.5% in y * across beam depths and energies. Bias averaged 6.2% and 7.3% in y ¯ F and y ¯ D , and 4.8% in y * . These uncertainties corresponded to 1.2 ± 0.9% on average in RBE MKM . The largest contributors to variance and bias were pulse pile-up and wall effects. This study established an error budget for microdosimetric carbon measurements by quantifying uncertainty inherent to TEPC measurements. It is necessary to understand how robust the measurement of RBE model input parameters are against this uncertainty in order to verify clinical model implementation.

1506 Background: Hereditary breast and ovarian cancer (HBOC) is preventable when genetic risk is identified. We aimed to test whether pre and/or post-test genetic counseling is needed to optimally deliver online accessible genetic testing. Methods: MAGENTA (Making GENetic Testing Accessible) is a four-arm non-inferiority trial evaluating electronic genetic education and results delivery alone or combined with pre-test only, or post-test only telephone genetic counseling compared to mandatory pre- and post-test counseling (control arm) in women at risk of HBOC (NCT02993068). Regardless of assigned arm, all subjects with a pathogenic mutation received post-test telephone counseling. All subjects were enrolled electronically as part of either a family history cohort (FHC) or a cascade cohort (CC, known familial mutation). The primary outcome was cancer risk distress at 3 months and the trial was powered for the FHC. Secondary outcomes included completion of testing (i.e., received results), anxiety, depression, quality of life, and decisional regret, all measured by standardized scales. Results: Enrollment is complete and a total of 3,822 participants were randomized, 3,111 in FHC and 711 in CC. Participants were enrolled from all 50 states, but most were white/non-Hispanic (88%). Among participants that completed genetic testing, 173 (7.2%) had a mutation in a breast or ovarian cancer gene, with 114 (5.7%) of FHC and 59 (14.2%) of CC. In the primary intention-to-treat analysis of FHC, each of the three experimental arms was non-inferior to the control arm for distress at 3 months (p < 0.025/3 = 0.0083). In the CC, no and pre-test only counseling were also non-inferior (p < 0.025/3 = 0.0083). Distress was lowest in the arm with neither pre nor post-test counseling. Overall, 318 (18%) participants had very high distress at three month follow-up, and this rate was not significantly different across arms. Anxiety, depression and decisional regret did not have statistically significant differences across arms at follow-up. Test completion was highest in the no counseling arm (86.4%) and lowest in the control arm (60.6%). Conclusions: Electronic genetic education and results release without genetic counseling was non-inferior with regard to patient distress and was associated with higher test completion and lower distress. These results support use of a genetic testing paradigm providing individualized genetic counseling only for patients with positive test results. Clinical trial information: NCT02993068.