Patel, Manan

e17027 Background: Guidelines recommend active surveillance for low-risk prostate cancer and definitive therapy for high-risk disease. We evaluated national patterns of risk-misaligned care and the survival consequences of undertreatment. Methods: National Cancer Database prostate cancer cases diagnosed from 2010–2022 were analyzed. Low-risk disease was defined as clinical T1–T2, Grade Group 1, and PSA < 10; overtreatment was definitive treatment vs active surveillance or no treatment. High-risk disease was defined as Grade Group ≥4, PSA ≥20, or clinical T3–T4; undertreatment was no definitive local therapy or incomplete definitive therapy. Multivariable logistic regression evaluated factors associated with misalignment. Overall survival (OS) among high-risk patients was assessed using multivariable Cox regression. Results: Among low-risk patients (N = 124,562), overtreatment occurred in 40% of cases. Overtreatment was more common among young men (adjusted odds ratio [aOR] 0.982; p < 0.001) and less common at academic centers (aOR 0.414; p = 0.015). Compared with White men, odds of overtreatment were lower among Black men (aOR 0.946; p = 0.002) and Asian men (aOR 0.827; p < 0.001), with additional variation by education and region (all p < 0.001). Among high-risk patients (N = 318,532), undertreatment affected 27.3% of patients and was more common among older men (aOR 1.061; p < 0.001). Compared with White men, undertreatment was higher among Black men (aOR 1.479; p < 0.001) and lower among Asian patients (aOR 0.863; p < 0.001) (overall race p < 0.001). Compared with private insurance, undertreatment was higher in Medicaid (aOR 2.038; p < 0.001) and uninsured patients (aOR 2.649; p < 0.001), and slightly lower with Medicare (aOR 0.931; p < 0.001) (overall insurance p < 0.001). Multiple comorbidities were associated with higher undertreatment (≥2 vs 0: aOR 1.252; p < 0.001). Facility type was not independently associated (p = 0.490), while region remained significant (overall p < 0.001). In the survival cohort (high risk) (N = 338,919), undertreatment was associated with substantially worse OS (HR 2.745, 95% CI 2.706–2.784; p < 0.001), adjusted for age (HR 1.056; p < 0.001), race (p = 0.001), insurance (p < 0.001), comorbidity (p < 0.001), income (overall p < 0.001), education (overall p < 0.001), and facility region (overall p < 0.001). Conclusions: Low-risk overtreatment remains common nationwide and varies across patient and health-system factors. In high-risk disease, undertreatment affects over one-quarter of patients and disproportionately impacts Black men and those with Medicaid or no insurance. Undertreatment confers a nearly threefold mortality hazard (adjusted HR 2.75; p < 0.001), highlighting a major national quality gap and the urgent need for system-level interventions to ensure equitable, guideline-concordant delivery of definitive therapy.

590 Background: The landmark FAST-Forward trial demonstrated that ultra-hypofractionated whole-breast irradiation with 26 Gy in 5 fractions over 1 week was non-inferior to 40 Gy in 15 fractions for local control (HR 0.67, 95% CI 0.38–1.16), with similar normal tissue effects at 5 years. In response, major international guidelines incorporated 26 Gy in 5 fractions as a standard approach or recommended option for selected patients. Despite robust randomized evidence and guideline endorsement, U.S. real-world adoption patterns and equity of uptake across patient populations remain incompletely characterized. This study evaluated national trends in 5-fraction breast radiotherapy and sociodemographic differences from 2020 to 2023. Methods: The National Cancer Database radiotherapy fractionation fields were used to identify radiotherapy (RT) courses with evaluable fraction counts, and a binary indicator for 5-fraction RT (yes/no) was created. Temporal trends by diagnosis year (2020–2023) were assessed, and associations between 5-fraction RT and sociodemographic factors (primary insurance, urban or rural status, neighborhood income quartile, and race) were examined using chi-square testing. Results: Among 536,783 RT courses with complete data from 2020 to 2023, use of 5-fraction RT increased substantially over time: 4.3% in 2020, 8.1% in 2021, 12.7% in 2022, and 17.4% in 2023, resulting in an overall adoption rate of 10.7% (p < 0.001). In the subset eligible for fractionation (5, 15–16, 25–28 fractions; N = 31,448), 5-fraction RT accounted for 11.7% and differed significantly by insurance type (p < 0.001): Medicare 17.4%, Private 7.6%, Medicaid 5.9%, and Uninsured 6.9%. Geographic variation was notable (p < 0.001), ranging from 7.3% in mid-size metropolitan areas (250,000–1 million population) to 17.7%–18.1% in more remote or non-adjacent areas; large metropolitan areas (≥1 million) had 12.8% uptake. Neighborhood income showed a gradient (p < 0.001): 10.1% in the lowest quartile compared to 12.5% in the highest. Race was also associated with uptake (p < 0.001), with lower use among Black patients compared to White patients (9.4% vs 12.2%). Conclusions: In routine U.S. practice, adoption of 5-fraction breast RT increased rapidly from 2020 to 2023, with the most pronounced growth after 2021, reflecting the swift translation of trial evidence into clinical practice. However, uptake varies by insurance, geography, income, and race, indicating that diffusion is not uniform. Given the potential benefits of ultra-hypofractionation in reducing treatment burden and supporting timely completion, targeted implementation strategies, such as provider education, reimbursement alignment, and facility-level operational support, may be necessary to ensure equitable access as 5-fraction regimens become more widely adopted and potentially become the standard of care.