Deville, Curtiland

PURPOSE Randomized clinical trials (RCTs) have shown progression-free survival (PFS) benefits of metastasis-directed therapy (MDT) without androgen deprivation therapy for oligometastatic castration-sensitive prostate cancer (omCSPC). Most patients with bone metastatic (BM) omCSPC recur with additional bone disease after MDT. We hypothesized the BM-targeting alpha-emitter radium-223 dichloride (Ra223) could target subclinical bone disease and delay progression. METHODS This is an investigator-initiated, multicenter, open-label phase II RCT. Eligible men with recurrent omCSPC with ≥one bone metastasis (≤three on conventional imaging and/or ≤five on molecular imaging) were randomly assigned (1:1) to stereotactic ablative radiation (SABR) MDT alone or SABR MDT with Ra223 (six cycles). Primary end point was composite PFS. RESULTS From August 9, 2019, to March 2, 2023, 64 patients were randomly assigned, 33 to SABR MDT and 31 to SABR MDT/Ra223 balancing for key covariates. Most SABR MDT/Ra223 patients (87%) received six cycles of Ra223. The median PFS was 11.8 months with SABR MDT and 10.5 months with SABR MDT/Ra223 (adjusted hazard ratio [aHR], 1.42 [95% CI, 0.79 to 2.56]; P = .24). Seven patients (11%) experienced grade 3 treatment-related adverse events (no grade 4 or 5), 2 of 33 (6%) with SABR and 5 of 30 (17%) with SABR MDT/Ra223. Patients with high-risk (HiRi) pathogenic mutations in ATM , BRCA1/2 , RB1 , or TP53 had worse PFS (HR, 5.95 [95% CI, 1.83 to 19.3]; P = .003). Greater T-cell receptor (TCR) unique productive rearrangements were prognostic for improved PFS independent of the treatment arm (aHR, 0.45 [95% CI, 0.21 to 0.96]; P = .04). CONCLUSION Adding Ra223 to SABR MDT in BM omCSPC does not delay progression of disease. We provide evidence for an HiRi mutational signature and TCR repertoire as prognostic biomarkers in omCSPC treated with SABR MDT, highlighting the importance of collecting biological correlates in RCTs for omCSPC.

11009 Background: Gender & racial/ethnic leadership disparities have been independently identified in academic hematology/oncology (HO) and radiation oncology (RO). Here, we evaluate gender and racial/ethnic intersectionality from the trainee to the leadership level. Methods: All ACGME accredited HO and RO training program websites were queried to identify constituent trainees, academic faculty, program directors (PD) and department chairs (DC), with a leadership position defined as PD or DC. Individual gender & race/ethnicity was determined using externally validated software tools (Gender-API, NamSor, & Onolytics), publicly available descriptors, and image review. We grouped individuals into 6 categories: White Male (WM), White Female (WF), Asian Male (AM), Asian Female (AF), Underrepresented Groups in Medicine (as defined by AAMC) Male (URMM) and Female (URMF). The chi-squared goodness-of-fit test was applied to examine if deviations exist between the observed vs. expected proportions of gender/race dyads in trainees, PD, and DC compared to academic faculty. Results: We identified 7,722 individuals from 2019-2020: 1,759 trainees (HO=1525; RO=234), 5,726 faculty (HO=4834; RO=892), 242 PD (HO=149; RO=93) and 237 DC (HO=144; RO=93). Leadership positions were most often comprised by WM (52.6%), and least often comprised by URMF (2.9%). Combined HO/RO analysis revealed significant differences in the observed representation of trainees & DC vs expected levels based on total faculty, respectively: WM (33.7% & 60.3% vs. 42.3%), WF (19.2% & 13.9% vs. 22.3%), AM (20.75% & 16.9% vs. 16.4%), AF (17.9% & 2.5% vs. 12.7%), URMM (4.09% & 5.5% vs. 3.5%) and URMF (4.3% & 0.8% vs. 2.8%), p<0.01. No differences were seen between PD vs total faculty. On subset analysis, there were significant differences observed in HO programs at the trainee, PD and DC levels compared to total faculty, whereas significant differences in RO programs were seen only at the DC level [Table]. Conclusions: Gender & racial/ethnic disparity is present in academic oncology. Specifically, women of all races/ethnicities are proportionally underrepresented in DC positions in HO and RO programs. These data can serve as a benchmark to raise awareness and monitor progress towards a more balanced workforce in oncology.[Table: see text]

Abstract Background: A range pull-back device, such as a machine-related range shifter (MRS) or a universal patient-related range shifter (UPRS), is needed in pencil beam scanning technique to treat shallow tumors. Methods: three UPRS made by QFix (Avondale, PA, USA) allow treating targets across the body: U-shaped bolus (UB), anterior lateral bolus (ALB) and couch top bolus (CTB). HN patients who used the UPRS were tested. The in-air spot sizes were measured and compared in this study at snout positions: 15 cm, 25 cm, and 35 cm. A solid water phantom with the ALB placed at 0, 10 and 20 cm air gaps to the phantom surface was also measured using a single-field optimized pencil beam scanning field. The two dimensional dose maps at the middle of the spread-out Bragg peak were measured using ion chamber array MatriXX PT (IBA-Dosimetry, Schwarzenbruck, Germany) located at iso-center and compared with the treatment planning system. Results: A UPRS can be consistently placed close to the patient and maintains a relatively small spot size resulting in improved dose distributions. However, when a UPRS is non-removable (e.g. thick couch top), the quality of volumetric imaging is degraded due to their high Z material construction, hindering the value of Image-Guided Radiation Therapy (IGRT). Limitations of using UPRS with small air gaps include reduced couch weight limit, potential collision with patient or immobilization devices and challenges using non-coplanar fields with certain UPRS. Our experience showed the combination of a U-shaped bolus exclusively for a head-and-neck target and an MRS as complimentary for head-and-neck targets as well as for all other treatment sites may be ideal to preserve the dosimetric advantages of pencil beam scanning proton treatments across the body. Conclusion: We have described how to implement UPRS and MRS for various clinical indications using the PBS technique, and comprehensively reviewed the advantage and disadvantages of URPS and MRS. We recommend the removable UB to be employed for the brain and HN treatments only while an automated MRS is used for all proton beams that require RS but not convenient or feasible to UB.