Prospective phase II trial of preoperative hypofractionated proton therapy for extremity and truncal soft tissue sarcoma: the PRONTO study rationale and design

BACKGROUND

Oncologic surgical resection is the standard of care for extremity and truncal soft tissue sarcoma (STS), often accompanied by the addition of pre- or postoperative radiation therapy (RT). Preoperative RT may decrease the risk of joint stiffness and fibrosis at the cost of higher rates of wound complications. Hypofractionated, preoperative RT has been shown to provide acceptable outcomes in prospective trials. Proton beam therapy (PBT) provides the means to decrease dose to surrounding organs at risk, such as the skin, bone, soft tissues, and adjacent joint(s), and has not yet been studied in patients with extremity and truncal sarcoma.

METHODS

Our study titled "PROspective phase II trial of preoperative hypofractionated protoN therapy for extremity and Truncal soft tissue sarcOma (PRONTO)" is a non-randomized, prospective phase II trial evaluating the safety and efficacy of preoperative, hypofractionated PBT for patients with STS of the extremity and trunk planned for surgical resection. Adult patients with Eastern Cooperative Group Performance Status ≤ 2 with resectable extremity and truncal STS will be included, with the aim to accrue 40 patients. Treatment will consist of 30 Gy radiobiological equivalent of PBT in 5 fractions delivered every other day, followed by surgical resection 2-12 weeks later. The primary outcome is rate of major wound complications as defined according to the National Cancer Institute of Canada Sarcoma2 (NCIC-SR2) Multicenter Trial. Secondary objectives include rate of late grade ≥ 2 toxicity, local recurrence-free survival and distant metastasis-free survival at 1- and 2-years, functional outcomes, quality of life, and pathologic response.

DISCUSSION

PRONTO represents the first trial evaluating the use of hypofractionated PBT for STS. We aim to prove the safety and efficacy of this approach and to compare our results to historical outcomes established by previous trials. Given the low number of proton centers and limited availability, the short course of PBT may provide the opportunity to treat patients who would otherwise be limited when treating with daily RT over several weeks. We hope that this trial will lead to increased referral patterns, offer benefits towards patient convenience and clinic workflow efficiency, and provide evidence supporting the use of PBT in this setting.

TRIAL REGISTRATION

NCT05917301 (registered 23/6/2023).

Real-Time Gated Proton Therapy: Commissioning and Clinical Workflow for the Hitachi System

Purpose

To describe the commissioning of real-time gated proton therapy (RGPT) and the establishment of an appropriate clinical workflow for the treatment of patients.

Materials and Methods

Hitachi PROBEAT provides pencil beam scanning proton therapy with an advanced onboard imaging system including real-time fluoroscopy. RGPT utilizes a matching score to provide instantaneous system performance feedback and quality control for patient safety. The CIRS Dynamic System combined with a Thorax Phantom or plastic water was utilized to mimic target motion. The OCTAVIUS was utilized to measure end-to-end dosimetric accuracy for a moving target across a range of simulated situations. Using this dosimetric data, the gating threshold was carefully evaluated and selected based on the intended treatment sites and planning techniques. An image-guidance workflow was developed and applied to patient treatment.

Results

Dosimetric data demonstrated that proton plan delivery uncertainty could be within 2 mm for a moving target. The dose delivery to a moving target could pass 3%/3 mm gamma analysis following the commissioning process and application of the clinical workflow detailed in this manuscript. A clinical workflow was established and successfully applied to patient treatment utilizing RGPT. Prostate cancer patients with implanted platinum fiducial markers were treated with RGPT. Their target motion and gating signal data were available for intrafraction motion analysis.

Conclusion

Real-time gated proton therapy with the Hitachi System has been fully investigated and commissioned for clinical application. RGPT can provide advanced and reliable real-time image guidance to enhance patient safety and inform important treatment planning parameters, such as planning target volume margins and uncertainty parameters for robust plan optimization. RGPT improved the treatment of patients with prostate cancer in situations where intrafraction motion is more than defined tolerance.

Gender and the Receipt of the Association of Residents in Radiation Oncology Educator of the Year Award

Purpose

We hypothesized that there may be a gender disparity in the receipt of the Association of Residents in Radiation Oncology (ARRO) Educator of the Year Award and sought to elucidate factors that contribute to differences in award receipt.

Methods and Materials

Using a database provided by the American Society for Radiation Oncology, award recipients were identified from 2010 to 2022. Publicly available websites were accessed to obtain data regarding gender, years since residency graduation, percentage of female faculty, size of residency program, and program director designation. A 1-sample Z-test was used to assess whether the proportion of female ARRO award winners, defined as the proportion of female radiation oncology faculty members in the nominating universities that year, was significantly less than the population average. Secondary analyses used univariable binary logistic regression to identify global associations between gender, year since gradation, or program size.

Results

The lowest proportion of female awardees occurred in 2013 (14.3%) and the greatest proportion in 2022 (30.6%). Compared with the proportion of female faculty members in nominating programs for the respective year, there were significantly fewer female awardees in 2010 (18% female awardees vs 32% female faculty members; P = .02) and 2013 (14% female awardees vs 31% female faculty members; P = .01). There was a statistically significant increase in female awardees during the study period (P < .01). On logistic regression analysis, large program size (≥10 residents) (odds ratio [OR], 6.86; 95% CI, 2.71-23.1; P < .001) and medium program size (5-9 residents) (OR, 4.05; 95% CI, 1.60-13.7; P < .001) were associated with a greater proportion of female awardees compared with small program size (1-4 residents). There was no association between awardee gender and years since graduation.

Conclusions

A gender disparity was present in the receipt of ARRO Educator Awards. Residency chiefs, program directors, and chairs should work to ensure that a diverse slate of faculty is considered annually for the ARRO Educator Award.

Radiation Therapy Summary of the AUA/ASTRO Guideline on Clinically Localized Prostate Cancer

PURPOSE

Our purpose was to develop a summary of recommendations regarding the management of patients with clinically localized prostate cancer based on the American Urologic Association/ ASTRO Guideline on Clinically Localized Prostate Cancer.

METHODS

The American Urologic Association and ASTRO convened a multidisciplinary, expert panel to develop recommendations based on a systematic literature review using an a priori defined consensus-building methodology. The topics covered were risk assessment, staging, risk-based management, principles of management including active surveillance, surgery, radiation, and follow-up after treatment. Presented are recommendations from the guideline most pertinent to radiation oncologists with an additional statement on health equity, diversity, and inclusion related to guideline panel composition and the topic of clinically localized prostate cancer.

SUMMARY

Staging, risk assessment, and management options in prostate cancer have advanced over the last decade and significantly affect shared decision-making for treatment management. Current advancements and controversies discussed to guide staging, risk assessment, and treatment recommendations include the use of advanced imaging and tumor genomic profiling. An essential active surveillance strategy includes prostate-specific antigen monitoring and periodic digital rectal examination with changes triggering magnetic resonance imaging and possible biopsy thereafter and histologic progression or greater tumor volume prompting consideration of definitive local treatment. The panel recommends against routine use of adjuvant radiation therapy (RT) for patients with prostate cancer after prostatectomy with negative nodes and an undetectable prostate-specific antigen, while acknowledging that patients at highest risk of recurrence were relatively poorly represented in the 3 largest randomized trials comparing adjuvant RT to early salvage and that a role may exist for adjuvant RT in selected patients at highest risk. RT for clinically localized prostate cancer has evolved rapidly, with new trial results, therapeutic combinations, and technological advances. The recommendation of moderately hypofractionated RT has not changed, and the updated guideline incorporates a conditional recommendation for the use of ultrahypofractionated treatment. Health disparities and inequities exist in the management of clinically localized prostate cancer across the continuum of care that can influence guideline concordance.

Team Approach: Extremity Soft Tissue Sarcoma

» Synovial sarcoma is a soft tissue sarcoma that most commonly presents in the extremity in a periarticular location.» As the history and physical examination of patients with synovial sarcoma can overlap considerably with those of patients with non-oncologic orthopedic conditions, it is important that orthopedic surgeons maintain a high level of suspicion when caring for patients with extremity masses.» Soft tissue sarcomas are best treated using a team approach. Early recognition and referral to a multidisciplinary sarcoma team are crucial to ensure the best clinical outcome for the patient.

Oncology Physician Workforce Diversity: Rationale, Trends, Barriers, and Solutions

ABSTRACT

This chapter will discuss (1) the rationale for physician workforce diversity and inclusion in oncology; (2) current and historical physician workforce demographic trends in oncology, including workforce data at various training and career levels, such as graduate medical education and as academic faculty or practicing physicians; (3) reported barriers and challenges to diversity and inclusion in oncology, such as exposure, access, preparation, mentorship, socioeconomic burdens, and interpersonal, structural, systemic bias; and (4) potential interventions and evidence-based solutions to increase diversity, equity, and inclusion and mitigate bias in the oncology physician workforce.

Pilot Study Assessing Student Interest in Combined Residency Training Pathways with Radiation Oncology

PURPOSE/OBJECTIVE(S)

Radiation oncology (RO) is a small, highly specialized field, which most medical students have limited exposure to before having to decide what specialty to apply to for their graduate medical education (GME). This may ultimately limit the number and diversity of RO applicants. The purpose of this pilot study was to determine students' views on a combined pathway program between RO with internal medicine (IM), as well as other related medical specialties, as a potential means of overcoming some of these barriers to student interest in RO and the early decision point to solo training in RO.

MATERIALS/METHODS

An electronic survey was sent to 299 United States student members of the American Society for Radiation Oncology (ASTRO) between July-August 2022. Multiple choice and Likert-type questions were used to assess students' views on the potential advantages and disadvantages of a combined IM/RO training pathway, and interest in this potential combined pathway as well as other combined pathway programs with RO and other related subspecialties. The Mann-Whitney U and Kruskal-Wallis tests were used to compare the responses of subgroups of students stratified according to their gender identity, race, or ethnicity. The Wilcoxon signed rank test was used to compare all participants' interest in different combined pathway programs compared to RO/IM.

RESULTS

Eighty participants completed the survey (response rate 27%). Thirty-four participants (43%) were either very or extremely interested in pursuing a combined IM/RO residency (median Likert-type rating 3, IQR 2-4). The duration of a combined IM/RO training considered most preferable or ideal was five years (n = 57, 71%) or six years (n = 21, 26%). The most important potential advantages of a combined IM/RO pathway included greater flexibility in employment options (n = 51, 64%), enhanced general medical knowledge to facilitate ambitions in other career pathways (n = 46, 58%), improved patient care (n = 43, 54%), and having a pathway for combined hematologic/oncology and RO board certification (n = 46, 58%). In comparison to IM/RO, participants were significantly more interested in a combined RO and hematology/oncology program (median Likert-type rating 5, IQR 5-5, p = 0.005). Among the subgroup of 26 students who believed that it was less likely that they would be applying for RO residency, 18 (69%) believed that the availability of an IM/RO pathway would increase their interest in applying to RO (median Likert-type rating 4, IQR 3-5). Interest in IM/RO did not differ by gender, race, or ethnicity.

CONCLUSION

Combined training pathways involving RO were viewed positively by most survey respondents, comprised of student members of ASTRO. Such programs may be particularly appealing to those students who are interested, but less committed to pursuing, a career in RO. Further research will help guide recommendations for the creation of these programs.

Gender and the Receipt of the Association of Residents in Radiation Oncology (ARRO) Educator of the Year Award

PURPOSE/OBJECTIVE(S)

Despite an increase in female physicians in recent years, a gender disparity remains in the field of radiation oncology. We hypothesized that there may be a gender disparity in the receipt of ARRO educator awards.

MATERIALS/METHODS

Using a database provided by the American Society for Radiation Oncology (ASTRO), annual award recipients were identified from 2010-2022. Data on Academic Institution, Year of Award, and Repeat Awardee Status were obtained through the ASTRO database. Publicly available websites were accessed to obtain data regarding gender, years post residency graduation, percent female/male faculty, size of residency program, and program director designation. H- indices were obtained from Scopus and used as a marker of academic productivity. Basic summary statistics, stratified by gender, were calculated for award year, years since graduation, percent of male faculty, and program size. A one-sample Z-test for proportions was utilized to assess if the proportion of female ARRO award winners each year from 2010 to 2022 was significantly less than the population average, defined as the proportion of female radiation oncology faculty members in the nominating universities that year. Secondary analyses used univariable binary logistic regression to identify any global associations between gender, year since gradation, or program size.

RESULTS

The lowest proportion of female awardees occurred in 2013 (8 [14.3%] females vs. 48 [85.7%] males) and the greatest proportion of female awardees occurred in 2022 (19 [30.6%] females vs. 43 [69.4%] males). As compared to the proportion of female faculty members in nominating programs for that respective year, there were significantly fewer female awardees in the years of 2010 (18% female awardees vs. 32% female faculty members, p = 0.02) and 2013 (14% female awardees vs. 31% female faculty members, p = 0.01). There was a statistically significant rise in female awardees over the study period (p<0.01). On logistic regression analysis, large program size (10+ residents) (odds ratio [OR]: 6.86, 95% confidence interval [CI]: 2.71-23.1, p<0.001) and medium program size (5-9 residents) (OR: 4.05, 95% CI: 1.60-13.7, p<0.001) were associated with a greater proportion of female awardees as compared to small program size (1-4 residents). There was no association between awardee gender and years since graduation.

CONCLUSION

A gender disparity is present in the receipt of ARRO Educator Awards. At an institutional level, residency Chiefs, Program Directors, and Chairs should work to ensure that a diverse slate of faculty are considered annually for the ARRO Educator Award with self-assessment of awardees over time to ensure demographic representation and inclusion. Efforts should also be made to recognize biases in resident evaluations of faculty with continued education about inherent biases.

Stereotactic Radiotherapy Deserts are Under-Represented among Radiation Oncology Alternative Payment Model Sites

PURPOSE/OBJECTIVE(S)

In bundled payment models including the proposed Radiation Oncology Alternative Payment Model (RO-APM), reimbursement favors shorter treatment paradigms like stereotactic radiotherapy (SRT). However, SRT requires specialized equipment, staff, and quality assurance procedures not available across the US. To understand the geospatial distribution of SRT and its impact on bundled payment models, we investigated the interplay between SRT resources with sociodemographic characteristics and oncologic outcomes for an index site of prostate cancer (PC).

MATERIALS/METHODS

We constructed an ecologic study model using data from the HRSA Area Health Resources, AMA Physician Masterfile, USDA Agriculture Economic Research Service, Medicare Provider and Service Files, and NIH Cancer State Profiles. SRT use was operationalized as the presence of Medicare SRT billing codes. Sociodemographic variables included county racial distributions, %poverty, and rural vs. urban classification. Provider to patient at risk density (PPRD) was defined as number of radiation oncologists per 100,000 males ≥65 years. PC incidence and death rates were evaluated. Uni- and multivariable logistic regressions examined links between SRT use, proposed RO-APM status, PPRD, sociodemographic variables, and PC oncologic outcomes at the US county level. All listed statistics demonstrated p <0.05.

RESULTS

SRT use was identified in 13% of all 3140 counties and in 49% of counties with documented RO providers. In univariable analyses, odds of SRT use was higher in counties that were metro [odds ratio (OR) 19.9] and with higher %Black constituents (OR 6.95); odds decreased with higher %poverty (OR 0.92). Among counties with RO providers, odds of SRT use increased with higher PPRD (OR 1.01). Odds of SRT use was associated with higher PC incidence (1.01) but lower death rates (OR 0.99). SRT use was more common in participating RO-APM counties (OR 2.66); moreover, magnitude and direction of associations between sociodemographic variables and RO-APM participation were similar to those for SRT use. In multivariable analysis, SRT use remained significantly associated with metro status, %Black constituents, PPRD, and PC death rates.

CONCLUSION

Both SRT use and proposed RO-APM participation were most prevalent in metro counties with higher PPRD and %Black populations, likely reflecting presence of densely populated cities with high health resources. If SRT is incentivized in future reimbursement models, then rural, lower resource communities without SRT may be disadvantaged. Lack of association between SRT and PC incidence indicates the presence of "SRT deserts"-counties with high oncologic need but no SRT. To enable visualization of SRT deserts and encourage interventions aimed at reducing disparities in SRT access, our results will be included in an interactive web platform (bit.ly/density maps).

Comparison of Estimated Late Toxicities between IMRT and IMPT when Treating Retroperitoneal Sarcoma Preoperatively with Ultra-Hypofractionation

PURPOSE/OBJECTIVE(S)

While preoperative radiation did not improve abdominal recurrence-free survival for retroperitoneal sarcoma (RPS) in the randomized STRASS trial, it did reduce rates of local recurrence. The risk of radiation-associated toxicity is substantial, with 77% of irradiated patients experiencing grade ≥3 lymphopenia in STRASS. Thus, finding methods to mitigate the issues of delaying surgery and irradiating normal tissue may provide a path towards affording the benefits of radiation while limiting its downside. One potential solution involves the use of hypofractionation to limit delay from radiation initiation to surgery, and proton therapy to limit dose to surrounding organs at risk (OARs). We conducted a dosimetric comparison of preoperative ultra-hypofractionated intensity-modulated photon radiotherapy (IMRT) and proton therapy (IMPT) for RPS, comparing estimated rates of late toxicity using published normal tissue complication probability (NTCP) models.

MATERIALS/METHODS

Volumetric modulated arc therapy IMRT and IMPT plans were generated on 10 RPS patients previously treated with preoperative radiation. The prescription was 25 Gy radiobiological equivalent (GyE) to the clinical target volume (CTV) and 30 GyE to the margin-at-risk, all in five fractions. Proton doses were calculated using a radiobiological effective dose of 1.1. NTCPs were calculated for each OAR as a function of equivalent uniform dose. The ΔNTCP (difference in absolute NTCP between IMRT and IMPT plans) for each of the toxicity domains was calculated. Student T-tests were used to compare differences in dosimetric and NTCP outcomes.

RESULTS

CTV coverage was met for all IMRT and IMPT plans with >99% of CTVs receiving ≥100% of prescription doses. The following endpoints were significantly lower with IMPT than IMRT: mean doses to liver, bone, and all analyzed genitourinary and gastrointestinal OARs; bowel, kidney, and bone V5-V20; stomach V15; liver V5; maximum doses to stomach, spinal canal, and body; and whole-body integral dose. No OAR endpoint was significantly higher with IMPT. The average ΔNTCP for grade 3 bowel ulceration/perforation and renal toxicity was 1.9% (p = .037) and 43.0% (p = .023), respectively, favoring IMPT. Using a model-based selection threshold of any ΔNTCP >10%, 50% (n = 5) of patients would be eligible for IMPT.

CONCLUSION

IMPT maintained target coverage while significantly reducing dose to adjacent OARs and integral dose compared to IMRT. This translated to significantly lower risks of estimated late gastrointestinal and renal toxicities with IMPT. Further investigation is warranted to validate these findings and potential clinical benefit in the management of RPS. A prospective trial treating RPS with preoperative ultra-hypofractionated IMPT at our institution is currently being pursued (NCT05302570).

Inaugural Experience with Real-time Gated Liver Proton SBRT and Treatment Plan Quality Improvement

PURPOSE/OBJECTIVE(S)

DIBH SBRT is routinely used for liver proton therapy. While intra-fraction target motion is limited with DIBH, acquisition of DIBH CT simulations in triplicate, as is done at our institution, reveals that variation does exist between each DIBH scan. The related target position can also vary correspondingly. The most common setup uncertainty for robust proton SBRT liver plan used at our institution is 5 mm sup-inf (SI) and 3 mm radially. Real-time gated proton therapy (RGPT) has the potential to provide instantaneous feedback for intra-fraction target motion to maximize patient safety and inform optimal treatment planning. Our first RGPT liver SBRT with intra-fraction motion under deep inspiration breath hold (DIBH). The potential treatment plan quality improvement brought by RGPT is investigated.

MATERIALS/METHODS

The following metrics were used in establishing our RGPT proton DIBH SBRT liver program: the iso center is always set at the fiducial mark; the beam orientation is selected to achieve both good plan quality and tracking performance; daily CBCTs are acquired and verified using fiducial maker position with kV images; robust uncertainty is determined by the gating tolerance; SBRT plan has three beams with uniform dose. Target motion was monitored throughout treatment. To evaluate dose sparing for surrounding OARs, a plan with tighter gating tolerance (3 mm SI and 2 mm radially) is optimized for dosimetric comparison. Statistical analyses were conducted using a programming environment.

RESULTS

Each of the three proton beams were delivered using DIBH over a total of 120-140 seconds. The average beam on time were 61.4, 66.9 and 62.8 seconds. The intra-fraction motion showed that targets could move up to 3 mm within the same DIBH. The motion increased with time. The table details the mean, maximum, standard deviation, and estimated upper 95% of directional shifts for three beams. Based on these results, plan delivery efficiency was maintained even with tighter gating tolerance. The comparison plan with tight gating tolerance showed significantly less dose (-25%) to the stomach in coronal view.

CONCLUSION

RGPT successfully tracked fiducial marker motion for DIBH SBRT liver treatment. Despite target drift during DIBH, the uncertainty of our DIBH SBRT procedure was sufficient to cover target motion throughout treatment. Based on the target drift value, a maximum of 25 seconds for breath hold time should be employed. Utilizing a tighter gating tolerance of 3 mm SI and 2 mm radially has the potential to maintain target coverage while significantly reducing OAR dose. Aggregated RGPT-derived data may provide optimal treatment planning parameters such as variable uncertainty based on target location.

Comparative In Silico Analysis of Ultra-Hypofractionated Intensity-Modulated Photon Radiotherapy (IMRT) Versus Intensity-Modulated Proton Therapy (IMPT) in the Pre-Operative Treatment of Retroperitoneal Sarcoma

BACKGROUND

While pre-operative radiation did not improve abdominal recurrence-free survival for retroperitoneal sarcoma (RPS) in the randomized STRASS trial, it did reduce rates of local recurrence. However, the risk of toxicity was substantial and the time to surgery was prolonged. A combination of hypofractionation and proton therapy may reduce delays from the initiation of radiation to surgery and limit the dose to surrounding organs at risk (OARs). We conducted a dosimetric comparison of the pre-operative ultra-hypofractionated intensity-modulated photon (IMRT) and proton radiotherapy (IMPT).

METHODS

Pre-operative IMRT and IMPT plans were generated on 10 RPS patients. The prescription was 25 Gy radiobiological equivalents (GyEs) (radiobiological effective dose of 1.1) to the clinical target volume and 30 GyEs to the margin at risk, all in five fractions. Comparisons were made using student T-tests.

RESULTS

The following endpoints were significantly lower with IMPT than with IMRT: mean doses to liver, bone, and all genitourinary and gastrointestinal OARs; bowel, kidney, and bone V5-V20; stomach V15; liver V5; maximum doses to stomach, spinal canal, and body; and whole-body integral dose.

CONCLUSIONS

IMPT maintained target coverage while significantly reducing the dose to adjacent OARs and integral dose compared to IMRT. A prospective trial treating RPS with pre-operative ultra-hypofractionated IMPT at our institution is currently being pursued.

Dose evaluation of inter- and intra-fraction prostate motion in extremely hypofractionated intensity-modulated proton therapy for prostate cancer

Inter- and intra-fractional prostate motion can deteriorate the dose distribution in extremely hypofractionated intensity-modulated proton therapy. We used verification CTs and prostate motion data calculated from 1024 intra-fractional prostate motion records to develop a voxel-wise based 4-dimensional method, which had a time resolution of 1 s, to assess the dose impact of prostate motion. An example of 100 fractional simulations revealed that motion had minimal impact on planning dose, the accumulated dose in 95 % of the scenarios fulfilled the clinical goals for target coverage (D95 > 37.5 Gy). This method can serve as a complementary measure in clinical setting to guarantee plan quality.

In silico comparison of whole pelvis intensity-modulated photon versus proton therapy for the postoperative management of prostate cancer

BACKGROUND

Limited data exist comparing intensity-modulated photon (IMRT) and proton (IMPT) radiation therapy when treating the prostate bed and pelvic lymph nodes in the postoperative setting for prostate cancer. The aim of this study was to evaluate dosimetric differences between IMRT and IMPT when treating with whole pelvis radiation therapy (WPRT) postoperatively.

MATERIALS AND METHODS

IMRT and IMPT plans were generated for 10 post-prostatectomy patients treated between July and August 2020. The prescription was 50 Gy radiobiologic equivalent (GyE) (proton radiobiological effective dose 1.1) to the pelvis and 70 GyE to the prostate bed in 2 GyE per fraction. Paired 2-sided Wilcoxon signed-rank tests were used to compare clinical target volume (CTV) coverage and dose to organs at risk (OARs).

RESULTS

CTV coverage was met for all plans with 99% of CTVs receiving ≥99% of prescription doses. Dose to OARs was significantly higher with IMRT than IMPT for the following endpoints: bladder V5-V65; bowel V5-V45; sigmoid V5-V50; rectum V5-V70; femoral head V40 and maximum dose; bone V5-V65. Select endpoints with significant differences included bladder V30 (63.5 vs. 44.4%, p < .001), bowel V15 (949 vs. 191 cc, p = .001) and V30 (386 vs. 121 cc, p < .001), rectum V40 (81.8 vs. 32.1%, p < .001) and V50 (47.6 vs. 24.9%, p < .001), femoral head maximum doses (46.4-47.1 vs. 38.3-38.6GyE, p < .001), and bone V10 (93.3 vs. 85.4%, p < . 001). Mean doses for all OARs were significantly higher with IMRT, including bladder (41.9 vs. 29.7GyE, p < .001), bowel (21.2 vs. 5.5GyE, p < .001), and rectum (50.8 vs. 27.3GyE, p < .001). Integral dose to 'Body - CTV' was significantly higher with IMRT (32.8 vs. 18.4 J, p < .001).

CONCLUSION

IMPT provides comparable target coverage to IMRT when treating prostate cancer with WPRT in the postoperative setting while significantly reducing dose to OARs. These data can inform the future clinical management and delivery of post-prostatectomy irradiation for prostate cancer.

The Current State of Departmental Diversity, Equity, and Inclusion Efforts Within US Academic Radiation Oncology Departments

PURPOSE

Promoting a diverse workforce of health care professionals that delivers equitable patient care is an important goal in oncology, as in all of medicine. Although most medical schools have a diversity office and associated initiatives, little is known about radiation oncology (RO) department-level efforts to promote diversity, equity, and inclusion (DEI). We describe the current state of DEI leadership and initiatives in RO departments in the US to guide future policies and programs.

METHODS AND MATERIALS

A total of 124 US RO departments affiliated with a medical school were contacted to identify departmental DEI leadership. Identified DEI leaders were asked to complete an anonymous survey assessing characteristics of their departmental DEI leadership, committee/organizational structure, activities, and perceived barriers to, and effect of, their work. Descriptive statistics are reported.

RESULTS

Among 85 RO departments that responded (68.5% response rate), 48 (56.5%) reported having a departmental DEI leader. Thirty-four DEI leaders completed the survey (70.8%). Of those who answered each survey question, most DEI leaders were assistant or associate professors (n = 24, 82.8%), women (n = 19, 73.1%), and identified with at least one non-White race or Hispanic ethnicity (n = 15, 53.6%). Nineteen (57.6%) had an associated departmental DEI committee; with 10 of these starting in 2020 or later. Few DEI leaders had administrative support (38.2%), funding (29.4%), protected time (23.5%), or increased compensation for added duties Fifteen (50.0%) believed their DEI-focused efforts were considered for promotion. The most reported initiatives included offering programming/education, supporting students from backgrounds underrepresented in medicine, improving recruitment practices/hiring, and implementing pipeline/pathway projects. The perceived impact of DEI initiatives included an increased culture of respect (89.7%), improved health care disparity awareness (75.9%), and improved systemic/structural racism awareness (79.3%).

CONCLUSIONS

Departmental DEI efforts are increasingly common within RO, however, the structure, resources, and recognition associated with DEI work are variable. Additional dedicated resources and recognition for these efforts will help ensure a culture of inclusive excellence for the RO workforce and patients.

Case-Matched Outcomes of Proton Beam and Intensity-Modulated Radiation Therapy for Localized Prostate Cancer

Purpose

Although both intensity-modulated radiation therapy (IMRT) and proton beam therapy (PBT) offer effective long-term disease control for localized prostate cancer (PCa), there are limited data directly comparing the 2 modalities.

Methods

The data from 334 patients treated with conventionally fractionated (79.2 GyRBE in 44 fractions) PBT or IMRT were retrospectively analyzed. Propensity score matching was used to balance factors associated with biochemical failure-free survival (BFFS). Age, race, and comorbidities (not BFFS associates) remained imbalanced after matching. Univariable and covariate-adjusted multivariable (MVA) Cox regression models were used to determine if modality affected BFFS.

Results

Of 334 patients, 176 (52.7%) were included in the matched cohort with exact matching to National Comprehensive Cancer Network (NCCN) risk group. With a median follow-up time of 9.0 years (interquartile range [IQR]: 7.8-10.2 years), long-term BFFS was similar between the IMRT and PBT matched arms with 8-year estimates of 85% (95% CI: 76%-91%) and 91% (95% CI: 82%-96%, P = .39), respectively. On MVA, modality was not significantly associated with BFFS in both the unmatched (hazard ratio [HR] = 0.75, 95% CI: 0.35-1.63, P = .47) and matched (HR = 0.87, 95% CI: 0.33-2.33, P = .78) cohorts. Prostate cancer-specific survival (PCSS) and overall survival (OS) were also similar (P > .05). However, in an unmatched analysis, the PBT arm had significantly fewer incidences of secondary cancers within the irradiated field (0.6%, 95% CI: 0.0%-3.1% versus 4.5%, 95% CI: 1.8%-9.0%, P = .028).

Conclusions

Both PBT and IMRT offer excellent long-term disease control for PCa, with no significant differences between the 2 modalities in BFFS, PCSS, and OS in matched patients. In the unmatched cohort, fewer incidences of secondary malignancy were noted in the PBT group; however, owing to overall low incidence of secondary cancer and imbalanced patient characteristics between the 2 groups, these data are strictly hypothesis generating and require further investigation.

A Medicare Claims Analysis of Racial and Ethnic Disparities in the Access to Radiation Therapy Services

PURPOSE

Reduced access and utilization of radiation therapy (RT) is a well-documented healthcare disparity observed among racial and ethnic minority groups in the USA and a contributor to the inferior health outcomes observed among Black, Hispanic, and Native American patient groups. What is less understood are the points during the process of care following RT consultation at which patients either fail to complete their prescribed treatment or encounter delays. Identification of those points where significant differences exist among different patient groups may help identify opportunities to close gaps in the access of clinically indicated RT.

METHODS AND MATERIALS

This analysis examines 261,559 RT episodes abstracted from Medicare claims and beneficiary data between 2016 and 2018 to determine rates of treatment initiation following planning and timeliness of treatment completion for different racial groups.

RESULTS

Failure to initiate treatment was observed to be 29.3% relatively greater for Black, Hispanic, and Native American patients than for White and Asian patients. Among episodes for which treatment was initiated, Black and Hispanic patients were observed to require a significantly greater number of calendar days (when adjusted for fraction number) for completion than for White, Asian, and Native American patients.

CONCLUSIONS

There appears to be a patient cohort for which RT disparities may be more marginal in their effects-allowing for access to consultation and treatment prescription but not for treatment initiation or timely completion of treatment-and may therefore permit effective solutions to help address current differences in cancer outcomes.

Development of a United States Radiation Oncology Curricular Framework: A Stakeholder Delphi Consensus

PURPOSE

A United States (US) radiation oncology curriculum, developed using best practices for curriculum inquiry, is needed to guide residency education and qualifying examinations. Competency-based training, including entrustable professional activities (EPAs), provides an outcomes-based approach to modern graduate medical education. This study aimed to define US radiation oncology EPAs and curricular content domains using a deliberative process with input from multiple stakeholder groups.

METHODS AND MATERIALS

The Radiation Oncology Education Collaborative Study Group Core Curriculum Project Leadership Committee developed initial content domains and EPAs. Following recruitment of stakeholders, a Delphi process was used to achieve consensus. In the first round, content domains and EPAs were reviewed for inclusion and exclusion, clarity, time allocation (content domains), and level of training (EPAs). Participants submitted additional content domains and EPAs for consideration. Any content domains or EPAs 1 standard deviation below the median for inclusion and exclusion underwent Leadership Committee review. All participants completing the first Delphi round were invited to the second round. Percent curriculum time allocated for content domains and a single subdomain were finalized. New EPAs or EPAs undergoing major revisions were reviewed.

RESULTS

A total of 186 participants representing diverse stakeholder groups participated. One hundred fourteen completed the first Delphi round (61.3%). Of 114 invited, 77 participants completed the second round of the Delphi process (67.5%). Overall, 6 of 9 content domains met consensus, 1 content domain was removed, and 2 content domains were combined. Four subdomains of a single content domain were reviewed and met consensus. Consensus on percent time allocated per content domain and subdomain was reached. Of 55 initial EPAs, 52 final EPAs met consensus.

CONCLUSIONS

Deliberative curriculum inquiry was successfully used to develop a consensus on US radiation oncology content domains and EPAs. These data can guide the allocation of educational time in training programs, help inform weighting for qualifying examinations, and help guide clinical training and resident assessment.

External Beam Radiation Therapy With or Without Brachytherapy Boost in Men With Very-High-Risk Prostate Cancer: A Large Multicenter International Consortium Analysis

PURPOSE

Very-high-risk (VHR) prostate cancer (PC) is an aggressive subgroup with high risk of distant disease progression. Systemic treatment intensification with abiraterone or docetaxel reduces PC-specific mortality (PCSM) and distant metastasis (DM) in men receiving external beam radiation therapy (EBRT) with androgen deprivation therapy (ADT). Whether prostate-directed treatment intensification with the addition of brachytherapy (BT) boost to EBRT with ADT improves outcomes in this group is unclear.

METHODS AND MATERIALS

This cohort study from 16 centers across 4 countries included men with VHR PC treated with either dose-escalated EBRT with ≥24 months of ADT or EBRT + BT boost with ≥12 months of ADT. VHR was defined by National Comprehensive Cancer Network (NCCN) criteria (clinical T3b-4, primary Gleason pattern 5, or ≥2 NCCN high-risk features), and results were corroborated in a subgroup of men who met Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy (STAMPEDE) trials inclusion criteria (≥2 of the following: clinical T3-4, Gleason 8-10, or PSA ≥40 ng/mL). PCSM and DM between EBRT and EBRT + BT were compared using inverse probability of treatment weight-adjusted Fine-Gray competing risk regression.

RESULTS

Among the entire cohort, 270 underwent EBRT and 101 EBRT + BT. After a median follow-up of 7.8 years, 6.7% and 5.9% of men died of PC and 16.3% and 9.9% had DM after EBRT and EBRT + BT, respectively. There was no significant difference in PCSM (sHR, 1.47 [95% CI, 0.57-3.75]; P = .42) or DM (sHR, 0.72, [95% CI, 0.30-1.71]; P = .45) between EBRT + BT and EBRT. Results were similar within the STAMPEDE-defined VHR subgroup (PCSM: sHR, 1.67 [95% CI, 0.48-5.81]; P = .42; DM: sHR, 0.56 [95% CI, 0.15-2.04]; P = .38).

CONCLUSIONS

In this VHR PC cohort, no difference in clinically meaningful outcomes was observed between EBRT alone with ≥24 months of ADT compared with EBRT + BT with ≥12 months of ADT. Comparative analyses in men treated with intensified systemic therapy are warranted.

Phase II Randomized Study of Salvage Radiation Therapy Plus Enzalutamide or Placebo for High-Risk Prostate-Specific Antigen Recurrent Prostate Cancer After Radical Prostatectomy: The SALV-ENZA Trial

PURPOSE

We sought to investigate whether enzalutamide (ENZA), without concurrent androgen deprivation therapy, increases freedom from prostate-specific antigen (PSA) progression (FFPP) when combined with salvage radiation therapy (SRT) in men with recurrent prostate cancer after radical prostatectomy (RP).

PATIENTS AND METHODS

Men with biochemically recurrent prostate cancer after RP were enrolled into a randomized, double-blind, phase II, placebo-controlled, multicenter study of SRT plus ENZA or placebo (ClinicalTrials.gov identifier: NCT02203695). Random assignment (1:1) was stratified by center, surgical margin status (R0 v R1), PSA before salvage treatment (PSA ≥ 0.5 v < 0.5 ng/mL), and pathologic Gleason sum (7 v 8-10). Patients were assigned to receive either ENZA 160 mg once daily or matching placebo for 6 months. After 2 months of study drug therapy, external-beam radiation (66.6-70.2 Gy) was administered to the prostate bed (no pelvic nodes). The primary end point was FFPP in the intention-to-treat population. Secondary end points were time to local recurrence within the radiation field, metastasis-free survival, and safety as determined by frequency and severity of adverse events.

RESULTS

Eighty-six (86) patients were randomly assigned, with a median follow-up of 34 (range, 0-52) months. Trial arms were well balanced. The median pre-SRT PSA was 0.3 (range, 0.06-4.6) ng/mL, 56 of 86 patients (65%) had extraprostatic disease (pT3), 39 of 86 (45%) had a Gleason sum of 8-10, and 43 of 86 (50%) had positive surgical margins (R1). FFPP was significantly improved with ENZA versus placebo (hazard ratio [HR], 0.42; 95% CI, 0.19 to 0.92; P = .031), and 2-year FFPP was 84% versus 66%, respectively. Subgroup analyses demonstrated differential benefit of ENZA in men with pT3 (HR, 0.22; 95% CI, 0.07 to 0.69) versus pT2 disease (HR, 1.54; 95% CI, 0.43 to 5.47; Pinteraction = .019) and R1 (HR, 0.14; 95% CI, 0.03 to 0.64) versus R0 disease (HR, 1.00; 95% CI, 0.36 to 2.76; Pinteraction = .023). There were insufficient secondary end point events for analysis. The most common adverse events were grade 1-2 fatigue (65% ENZA v 53% placebo) and urinary frequency (40% ENZA v 49% placebo).

CONCLUSION

SRT plus ENZA monotherapy for 6 months in men with PSA-recurrent high-risk prostate cancer after RP is safe and delays PSA progression relative to SRT alone. The impact of ENZA on distant metastasis or survival is unknown at this time.

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.

Shorter Radiation Regimens and Treatment Noncompletion Among Patients With Breast and Prostate Cancer in the United States: An Analysis of Racial Disparities in Access and Quality

PURPOSE

Compared with conventional external-beam radiation therapy (cEBRT) for patients with breast cancer (BC) and prostate cancer (PC), shorter radiation regimens may be associated with lower treatment noncompletion rates. We assess disparities in receipt of shorter radiation regimens and treatment noncompletion for BC and PC.

PATIENTS AND METHODS

The 2004-2017 National Cancer Database was queried for adjuvant cEBRT or hypofractionated EBRT (hEBRT) for nonmetastatic BC; and definitive cEBRT, moderate hypofractionation (mEBRT), or stereotactic body radiotherapy (SBRT) for localized PC. Multivariable logistic regression identified factors associated with treatment noncompletion and receipt of shorter regimens.

FINDINGS

We identified 170,386 men with PC (median age [interquartile range], 70 [64-75] years; Black, 17.5%; White, 82.5%) and 306,846 women with BC (61 [52-69] years; Black, 12.3%; White, 87.7%). Among patients who received cEBRT for PC, Black men had higher treatment noncompletion rates compared with White (14.1% v 13.0%; odds ratio [95% CI] 1.07 [1.03 to 1.12]; P < .001). In contrast, treatment noncompletion was not disparate with SBRT (Black 1.6% v White 1.3%; 1.20 [0.72 to 2.00], P = .49) or mEBRT (Black 9.0% v White 7.1%; 1.05 [0.72 to 1.54], P = .79). From 2004 to 2017, SBRT (0.07% to 11.8%; 1.32 [1.31 to 1.33]) and mEBRT (0.35% to 9.1%; 1.27 [1.25 to 1.28]) increased (both P < .001); however, Black men were consistently less likely to receive SBRT (7.4% v White, 8.3%; 0.84 [0.79 to 0.89], P < .001). Among women with BC, there were no racial differences in treatment noncompletion; however, hEBRT was associated with lower treatment noncompletion rates (1.0% v cEBRT 2.3%; 0.39 [0.35 to 0.44], P < .001). Although hEBRT for BC increased (0.8% to 35.6%) between 2004 and 2017, Black women were less likely to receive hEBRT (10.4% v 15.3%; 0.78 [0.75 to 0.81], P < .001).

INTERPRETATION

Black patients were consistently less likely to receive hypofractionated radiation for PC or BC, despite evidence suggesting that shorter regimens may lower rates of treatment noncompletion with similar oncologic outcomes.

Radiotherapy Deserts: Impact of Race, Poverty and the Rural-Urban Continuum on Density of Providers and Utilization of Radiotherapy in the United States

PURPOSE

Prior efforts to characterize disparities in radiotherapy access and receipt have not comprehensively investigated interplay between race, socioeconomic status, and geography relative to oncologic outcomes. We sought to define these complex relationships at the US county level for prostate (PC) and invasive breast (BC) cancer in order to build a tool that facilitates identification of "radiotherapy deserts"-regions with mismatch between radiotherapy resources and oncologic need.

METHODS

We constructed an ecologic study model using national databases to evaluate 3141 US counties. Radiotherapy resources and utilization densities were operationalized as physician (PPR) and utilization (UPR) per person at risk: number of attending radiation oncologists and Medicare beneficiaries per 100,000 persons at risk, respectively. Oncologic need was defined by "hot zone" counties with ≥2 standard deviations (SD) above mean incidence and death rates. Uni- and multivariable logistic regressions examined links between PPR and UPR densities, epidemiologic variables, and hot zones for oncologic outcomes. Reported statistics are p<.05.

RESULTS

Mean (SD) PPR and UPR densities were 2.1 (5.9) and 192.6 (557.6) for PC and 1.9 (5.3) and 174.4 (501.0) for BC, respectively. Counties with high PPR and UPR densities were predominately Metro [odds ratio (OR) 2.9-4.4], generally with higher %Black Non-Hispanic population (OR 1.5-2.3). Incidence and death rate hot zones were largely Non-Metro (OR 0.3-0.6), generally with higher %Black Non-Hispanic constituents (OR 3.2-6.3). Lower PPR density was associated with death rate hot zones for both cancers (OR 0.8-0.9); UPR density was generally not linked to oncologic outcomes on multivariable analysis.

CONCLUSIONS

Mismatch between oncologic need with PPR and UPR disproportionately affects Non-Metro communities with higher %Black Non-Hispanic population. We developed an interactive web platform (bit.ly/densitymaps) to visualize "radiotherapy deserts" and drive targeted investigation of underlying barriers to care in areas of highest need, with the goal of reducing health inequities in this context.

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.

Using Holistic Residency Applicant Review and Selection in Radiation Oncology to Enhance Diversity and Inclusion, an ASTRO SCAROP-ADROP-ARRO Collaboration

Disproportionate gender, racial, and ethnic diversity remains in the radiation oncology physician workforce despite widespread awareness and longitudinal efforts to improve representation. In this collaborative review, we define the rationale and components of holistic review and how it can be best utilized to provide a comprehensive evaluation of applicants to residency programs in radiation oncology. We initially discuss the current state of diversity in the field of radiation oncology and highlight the components of the residency selection process that may serve to perpetuate existing biases. Subsequently, the ACGME and AAMC holistic review framework is reviewed in detail to demonstrate the balanced assessment of potential applicants. The implementation of holistic review in medical school and residency selection to-date are examined to underscore the potential value of holistic review in the radiation oncology residency selection process. Finally, recommendations for the practical implementation of holistic review in radiation oncology trainee selection are outlined.

Comparing Ultra-hypofractionated Proton versus Photon Therapy in Extremity Soft Tissue Sarcoma

Purpose

Recent single institution, phase II evidence has demonstrated the feasibility and efficacy of ultra-hypofractionated, preoperative photon therapy in 5 fractions for the treatment of soft tissue sarcoma (STS). Our purpose was to evaluate the dosimetric benefits of modern scanning beam proton therapy compared with conventional photon radiation therapy (RT) for the neoadjuvant treatment of adult extremity STS.

Materials and Methods

Existing proton and photon plans for 11 adult patients with STS of the lower extremities previously treated preoperatively with neoadjuvant RT at our center were used to create proton therapy plans using Raystation Treatment Planning System v10.A. Volumes were delineated, and doses reported consistent with International Commission on Radiation Units and Measurements reports 50, 62, and 78. Target volumes were optimized such that 100% clinical target volume (CTV) was covered by 99% of the prescription dose. The prescribed dose was 30 Gy for PT and RT delivered in 5 fractions. For proton therapy, doses are reported in GyRBE = 1.1 Gy. The constraints for adjacent organs at risk (OARs) within 1 cm of the CTV were the following: femur V30Gy ≤ 50%, joint V30Gy < 50%, femoral head V30Gy ≤ 5 cm3, strip V12 ≤ 10%, and skin V12 < 50%. Target coverage goals, OAR constraints, and integral dose were compared by Student t test with P < .05 significance.

Results

A minimum 99% CTV coverage was achieved for all plans. OAR dose constraints were achieved for all proton and photon plans; however, mean doses to the femur (10.7 ± 8.5 vs 16.1 ± 7.7 GyRBE), femoral head (2.0 ± 4.4 vs 3.6 ± 6.4 GyRBE), and proximal joint (1.8 ± 2.4 vs 3.5 ± 4.4 GyRBE) were all significantly lower with PT vs intensity-modulated radiation therapy (IMRT) (all P < .05). Integral dose was significantly reduced for proton vs photon plans. Conformity and heterogeneity indices were significantly better for proton therapy.

Conclusion

Proton therapy maintained target coverage while significantly reducing integral and mean doses to the proximal organs at risk compared with RT. Further prospective investigation is warranted to validate these findings and potential benefit in the management of adult STS.

Treatment Planning of Bulky Tumors Using Pencil Beam Scanning Proton GRID Therapy

Purpose

To compare spatially fractionated radiation therapy (GRID) treatment planning techniques using proton pencil-beam-scanning (PBS) and photon therapy.

Materials and Methods

PBS and volumetric modulated arc therapy (VMAT) GRID plans were retrospectively generated for 5 patients with bulky tumors. GRID targets were arranged along the long axis of the gross tumor, spaced 2 and 3 cm apart, and treated with a prescription of 18 Gy. PBS plans used 2- to 3-beam multiple-field optimization with robustness evaluation. Dosimetric parameters including peak-to-edge ratio (PEDR), ratio of dose to 90% of the valley to dose to 10% of the peak VPDR(D90/D10), and volume of normal tissue receiving at least 5 Gy (V5) and 10 Gy (V10) were calculated. The peak-to-valley dose ratio (PVDR), VPDR(D90/D10), and organ-at-risk doses were prospectively assessed in 2 patients undergoing PBS-GRID with pretreatment quality assurance computed tomography (QACT) scans.

Results

PBS and VMAT GRID plans were generated for 5 patients with bulky tumors. Gross tumor volume values ranged from 826 to 1468 cm³. Peak-to-edge ratio for PBS was higher than for VMAT for both spacing scenarios (2-cm spacing, P = .02; 3-cm spacing, P = .01). VPDR(D90/D10) for PBS was higher than for VMAT (2-cm spacing, P = .004; 3-cm spacing, P = .002). Normal tissue V5 was lower for PBS than for VMAT (2-cm spacing, P = .03; 3-cm spacing, P = .02). Normal tissue mean dose was lower with PBS than with VMAT (2-cm spacing, P = .03; 3-cm spacing, P = .02). Two patients treated using PBS GRID and assessed with pretreatment QACT scans demonstrated robust PVDR, VPDR(D90/D10), and organs-at-risk doses.

Conclusions

The PEDR was significantly higher for PBS than VMAT plans, indicating lower target edge dose. Normal tissue mean dose was significantly lower with PBS than VMAT. PBS GRID may result in lower normal tissue dose compared with VMAT plans, allowing for further dose escalation in patients with bulky disease.

A liquid immunogenic fiducial eluter for image-guided radiotherapy

Introduction

Fiducials are routinely used to provide image-guidance during radiotherapy. Here, a new nanoparticle-based liquid immunogenic fiducial is investigated for its potential to provide image-guidance, while also enhancing treatment outcomes.

Methods

This fiducial, liquid immunogenic fiducial eluter (LIFE) biomaterial, is formulated with natural biodegradable polymers, chitosan and sodium alginate with radio-sensitizing nanoparticles, and immunoadjuvant like anti-CD40 monoclonal antibody. Once administered intra-tumorally, this liquid smart radiotherapy biomaterial congeals within the calcium rich tumor microenvironment. The potential use of LIFE biomaterial for providing image guidance in magnetic resonance imaging (MRI) and computed tomography (CT) was investigated over different time period in a pre-clinical tumored mouse model.

Results

Results showed that the LIFE biomaterial can provide both MRI contrast and CT imaging contrast over 3-weeks, with gradual decrease of the contrast over time, as the LIFE biomaterial biodegrades. Results also showed the LIFE biomaterial significantly slowed tumor growth and prolonged mice survival (p < 0.0001) over time.

Discussion

The results highlight the potential use of the LIFE biomaterial as a multi-functional smart radiotherapy biomaterial that could be developed and optimized for hypo-fractionated radiotherapy applications and combining radiotherapy with immunoadjuvants.

Radiation Oncology resident perspectives on diversity, equity, and inclusion: an Association of Residents in Radiation Oncology Equity and Inclusion Subcommittee (ARRO EISC) inaugural resident survey

PURPOSE

In this study, radiation oncology residents were surveyed on perceptions of diversity, equity, inclusion, and belonging in their residency training programs.

METHODS AND MATERIALS

A 23-item survey was developed by the Association of Residents in Radiation Oncology Equity and Inclusion Subcommittee resident members and faculty advisors. The survey was divided into 4 sections: institutional culture, support and resources, interview and recruitment, and experiences of bias. The survey was sent individually to residents from all Accreditation Council for Graduate Medical Education-accredited radiation oncology programs.

RESULTS

The survey was issued to 757 residents. A total of 319 residents completed the survey, for a response rate of 42%. All postgraduate years and geographic regions were represented. Significant racial, ethnic, and gender differences were present in survey response patterns. White residents (94%, 164 of 174) and male residents (96%, 186 of 194) were more likely to strongly agree/agree that they were treated with respect by their colleagues and their coworkers than other racial groups (P < .005) or gender groups (P < .008). Only 3% (5 of 174) of White residents strongly agreed/agreed that they were treated unfairly because of their race/ethnicity, while 31% (5 of 16) of Black residents and 10% (9 of 94) of Asian residents strongly agreed/agreed (P < .0001). Similarly, Hispanic residents were more likely to strongly agree/agree (24%, 5 of 21) than non-Hispanic residents (7%, 20 of 298) (P = .003). Regarding mentorship, there were no differences by gender or ethnicity. There were differences by race in residents reporting that they had a supportive mentor (P = .022), with 89% (154 of 174) of White residents who strongly agreed/agreed, 88% (14 of 16) of Black residents, and 91% of Asian residents (86 of 94).

CONCLUSIONS

This survey reveals that experiences of support, mentorship, inclusion, and bias vary significantly among radiation oncology residents based on race, ethnicity, and gender. Radiation oncology has opportunity for growth to ensure an equitable experience for all residents.

Demographic trends among ASTRO clinical practice guideline task force participants from 2010-2022

PURPOSE

The American Society for Radiation Oncology (ASTRO) has produced evidence-based clinical practice guidelines since 2009. It is unknown whether task force members for these guidelines are representative of the diversity of the radiation oncology field, particularly in comparison to the ASTRO membership demographics. We sought to characterize the demographic composition of all task force members to date.

METHODS

The author list for ASTRO-led published guidelines from 2010 to 2022 was assessed. Main practice location/institution was extracted from the guideline publication. Self-identified gender and race/ethnicity were obtained from the ASTRO membership database. Years of experience were measured as the number of years post-board certification at time of guideline development. For United States (US)-based physicians, gender was confirmed with the National Provider Identifier database. Proportions of task force members overall and by individual guideline were described by gender, underrepresented in medicine (URM) status, geography (US vs international), US region (if US based), years of experience (separated into ≤5 years including residents, 6-12 years, and >12 years), and type of practice. Proportions for gender, URM, and geography were compared with ASTRO membership demographics.

RESULTS

Between 2010 and 2022, there were 25 guideline task forces, with a total of 366 participants: 233 men, 126 women, and 7 unknown gender. There were more men than women serving on most individual task force topics, with 28% of all task forces having >80% composition of men. Of those with self-identified race/ethnicity, 9/204 (4.4%) were URM, which was lower in proportion to URM self-identified ASTRO members (336/3277, 10.3%; P = .007). Most participants were based in the US (n = 323, 88.3%), had >12 years of experience (n = 141, 38.5%), and were from academic institutions (n = 302, 82.5%). Community practitioners were less likely to be women or URM.

CONCLUSIONS

Improved data collection and more intentional efforts are needed to ensure that the diversity of guidelines task forces is representative of ASTRO membership and the specialty.

Gender Differences Among Academic Radiation Oncology National Institutes of Health (NIH) Funding Recipients

Purpose

The purpose of our study was to evaluate National Institutes of Health (NIH) funding recipients between 2016 and 2019 to determine if there was an association between gender, research productivity, academic rank, leadership positions, and post-graduate awards.

Materials and Methods

The NIH Research Portfolio Online Reporting Tools Expenditure and Results (RePORTER) website was used to retrieve data for grants in Radiation Oncology from 2016-2019. Demographics and profiles of awardees were retrieved from institutional websites, LinkedIn, and Doximity. Publication metrics were collected through the Scopus database. Mann-Whitney U tests and chi-square analyses were performed to compare and determine associations between gender and other variables. 

Results

Three hundred and forty radiation oncology principal investigators (PIs) were included in this study, of whom 76% were men. Of the 776 total NIH grants awarded, 62% of the grants had a sole male PI and 1% had two or more PIs in which the contact PI and co-PI were women. Between the genders of PIs in this sample, there was no significant difference in highest academic rank, leadership positions (i.e., chair, director, founder, president, and other), and post-graduate honors and awards. Total publications, years of active research, h-index, and m-index were higher amongst men in the professor category but were largely similar between genders in the associate and assistant professor categories.

Conclusions

The results demonstrate that most NIH grants in radiation oncology were awarded to men. Strategies that increase women in radiation oncology (RO), as well as those that increase NIH grants amongst women may also increase the prevalence of women in senior academic ranks and leadership positions.

Genomic Testing in Localized Prostate Cancer Can Identify Subsets of African Americans With Aggressive Disease

BACKGROUND

Personalized genomic classifiers have transformed the management of prostate cancer (PCa) by identifying the most aggressive subsets of PCa. Nevertheless, the performance of genomic classifiers to risk classify African American men is thus far lacking in a prospective setting.

METHODS

This is a prospective study of the Decipher genomic classifier for National Comprehensive Cancer Network low- and intermediate-risk PCa. Study-eligible non-African American men were matched to African American men. Diagnostic biopsy specimens were processed to estimate Decipher scores. Samples accrued in NCT02723734, a prospective study, were interrogated to determine the genomic risk of reclassification (GrR) between conventional clinical risk classifiers and the Decipher score.

RESULTS

The final analysis included a clinically balanced cohort of 226 patients with complete genomic information (113 African American men and 113 non-African American men). A higher proportion of African American men with National Comprehensive Cancer Network-classified low-risk (18.2%) and favorable intermediate-risk (37.8%) PCa had a higher Decipher score than non-African American men. Self-identified African American men were twice more likely than non-African American men to experience GrR (relative risk [RR] = 2.23, 95% confidence interval [CI] = 1.02 to 4.90; P = .04). In an ancestry-determined race model, we consistently validated a higher risk of reclassification in African American men (RR = 5.26, 95% CI = 1.66 to 16.63; P = .004). Race-stratified analysis of GrR vs non-GrR tumors also revealed molecular differences in these tumor subtypes.

CONCLUSIONS

Integration of genomic classifiers with clinically based risk classification can help identify the subset of African American men with localized PCa who harbor high genomic risk of early metastatic disease. It is vital to identify and appropriately risk stratify the subset of African American men with aggressive disease who may benefit from more targeted interventions.

Évolution des paramètres nutritionnels après la discontinuation des collations intradialytiques à cause de l’épidémie COVID-19

Introduction

Pendant l’épidémie par le COVID-19 plusieurs centres de dialyse ont arrêté de fournir des collations pendant la séance de dialyse par mesure de protection de propagation du virus. Le but de cette étude est d’évaluer l’état nutritionnel des patients hémodialysés chroniques avant et après la suspension des collations intradialytiques.

Description

Sur cette étude rétrospective on a étudié l’évolution des paramètres nutritionnelles de notre cohorte des patients hémodialysés pour 12 mois avant et après le 20/03/2020, date de suspension des collations pendant la dialyse à cause des mesures de protection contre la COVID-19. On a suivi l’évolution du poids, IMC, CRP, sérum Potassium et Phosphore avant la séance de dialyse, le taux d’albumine et prealbumine sérique ainsi que le nPCR (normalised Protein Catabolic Ratio).

Méthodes

Les résultats pour les paramètres continues sont présentés comme Moyenne ± Erreur standard moyenne. Pour l’analyse statistique on a effectué un t-test pour mesures indépendantes. Les résultats avec un p < 0,05 était considérés statistiquement significatifs.

Résultats

On a étudié 121 patients en hémodialyse (80 M,41F) avec un âge moyen à l’inclusion de 68,45 ± 0,45 ans. Ils étaient dialysés au moins depuis 6 mois dans un état stable. Un tiers de ces patients était diabétique. On a mesuré la moyenne des paramètres étudiés pour douze mois avant et après la suppression de collations intradialytiques (voir (Tableau 1). Ces collations comprenaient en moyenne de 395 kcal d’énergie (44 % des besoins journaliers), 13,3 g de protides (40 % des besoins journaliers). Il y avait une dégradation des paramètres nutritionnelles (poids, IMC, Albumine et Prealbumine serique ainsi que le nPCR après la suppression des collations confirmant leur rôle important sur l’état nutritionnel des patients hémodialysés chroniques.

Conclusion

En conclusion, la suppression des collations intradialytiques pendant la période épidémique de COVID-19 a aggravé les paramètres nutritionnels des patients en hémodialyse chronique.

Health Disparities in Prostate Cancer and Approaches to Advance Equitable Care

The American Cancer Society estimates approximately 268,490 new cases of prostate cancer and approximately 34,500 deaths caused by prostate cancer in the United States for 2022. Globally, a total of 1,414,259 new cases of prostate cancer and 375,304 related deaths were reported in 2020. Well-documented health disparities and inequities exist along the continuum of care for prostate cancer management-from screening to diagnostic and staging work-up, surveillance, and treatment-ultimately impacting clinical outcomes. This session-based article discusses innovative patient-centered approaches to advance equitable prostate cancer care. It begins with a review of domestic health disparities in diagnostic imaging and radiotherapy for prostate cancer, and it summarizes barriers and solutions to achieving health equity, such as equity metrics and practice quality improvement projects. Next, a global perspective is provided that describes approaches to address financial and geographic barriers to prostate cancer care, including specific examples of strategies that emphasize the use of the cheapest method of care delivery while maintaining outcomes for drug delivery and radiotherapy.