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.

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.

Multidisciplinary total eradication therapy (TET) in men with newly diagnosed oligometastatic prostate cancer

To evaluate the outcomes of total eradication therapy (TET), designed to eradicate all sites of visible cancer and micrometastases, in men with newly diagnosed oligometastatic prostate cancer (OMPCa). Men with ≤ 5 sites of metastases were enrolled in a prospective registry study, underwent neoadjuvant chemohormonal therapy, followed by radical prostatectomy, adjuvant radiation (RT) to prostate bed/pelvis, stereotactic body radiation therapy (SBRT) to oligometastases, and adjuvant hormonal therapy (HT). When possible, the prostate-specific membrane antigen targeted ¹⁸F-DCFPyL PET/CT (¹⁸F-DCFPyL) scan was obtained, and abiraterone was added to neoadjuvant HT. Twelve men, median 55 years, ECOG 0, median PSA 14.7 ng/dL, clinical stages M0—1/12 (8%), M1a—3/12 (25%) and M1b—8/12 (67%), were treated. ¹⁸F-DCFPyL scan was utilized in 58% of cases. Therapies included prostatectomy 12/12 (100%), neoadjuvant [docetaxel 11/12 (92%), LHRH agonist 12/12 (100%), abiraterone + prednisone 6/12 (50%)], adjuvant radiation [RT 2/12 (17%), RT + SBRT 4/12 (33%), SBRT 6/12 (50%)], and LHRH agonist 12/12 (100%)]. 2/5 (40%) initial patients developed neutropenic fever (NF), while 0/6 (0%) subsequent patients given modified docetaxel dosing developed NF. Otherwise, TET resulted in no additive toxicities. Median follow-up was 48.8 months. Overall survival was 12/12 (100%). 1-, 2-, and 3-year undetectable PSA’s were 12/12 (100%), 10/12 (83%) and 8/12 (67%), respectively. Median time to biochemical recurrence was not reached. The outcomes suggest TET in men with newly diagnosed OMPCa is safe, does not appear to cause additive toxicities, and may result in an extended interval of undetectable PSA.

Cobalamin c deficiency associated with antifactor h antibody-associated hemolytic uremic syndrome in a young adult

Background

Thrombotic microangiopathy (TMA) syndromes are characterized by the association of hemolytic anemia, thrombocytopenia and organ injury due to arteriolar and capillary thrombosis.

Case presentation

We report the first case of adult onset cobalamin C (Cbl C) disease associated with anti-factor H antibody-associated hemolytic uremic syndrome (HUS).

A 19-year-old woman was admitted to the nephrology department owing to acute kidney failure, proteinuria, and hemolytic anemia with schizocytes.

TMA was diagnosed and plasma exchanges were started in emergency.

Exhaustive analyses showed 1) circulating anti factor H antibody and 2) hyperhomocysteinemia, hypomethioninemia and high levels of methylmalonic aciduria pointing towards Clb C disease. Cbl C disease has been confirmed by methylmalonic aciduria and homocystinuria type C protein gene sequencing revealing two heterozygous pathogenic variants.

The kidney biopsy showed 1) intraglomerular and intravascular thrombi 2) noticeable thickening of the capillary wall with a duplication aspect of the glomerular basement membrane and a glomerular capillary wall IgM associated with Cbl C disease related TMA.

We initiated treatment including hydroxycobalamin, folinic acid, betaine and levocarnitine and Eculizumab. Rituximab infusions were performed allowing a high decrease in anti-factor H antibody rate.

Six month after the disease onset, Eculizumab was weaning and vitaminotherapy continued. Outcome was favorable with a dramatic improvement in kidney function.

Conclusion

TMA with renal involvement can have a complex combination of risk factors including anti-FH autoantibody in the presence of cblC deficiency.