Abstract 3812: Treatment guideline concordance for patients with metastatic hormone-sensitive prostate cancer (mHSPC) in the United States in IRONMAN, the International Registry for Men with Advanced Prostate Cancer
Authors: McManus Hannah Dzimitrowicz , Howard Lauren , Crowell Kerri-Anne , Hyslop Terry , Vinson Jake , Rathkopf Dana E. , Kantoff Philip , Mucci Lorelei A. , George Daniel , Stopsack Konrad 
Published: March 2024

Abstract
Background: Treatment intensification strategies with an androgen receptor pathway inhibitor (ARPI) and/or docetaxel chemotherapy in addition to androgen deprivation therapy (ADT) are guideline recommended treatment options for patients with metastatic hormone-sensitive prostate cancer (mHSPC). Prevalence of guideline concordant care for mHSPC patients in the US and its changes over time are not well characterized.
Methods: The International Registry for Men with Advanced Prostate Cancer (IRONMAN) is a prospective cohort study of patients with newly diagnosed mHSPC and castration-resistant prostate cancer (CRPC). Therapies are captured by site personnel and by directly capturing data from treating physicians via physician questionnaires (PQ). We included all US patients with mHSPC enrolled from 2018 to January 1, 2023 with a completed PQ at enrollment. We examined patient characteristics, first-line treatments for mHSPC, and guideline concordance of first-line treatments. Guideline concordance was defined as a treatment regimen listed in the first National Comprehensive Cancer Network guidelines version for the year prior to treatment. Patients enrolled in clinical trials were excluded from analysis of treatment guideline concordance.
Results: Among the 636 US participants with mHSPC, physicians completed PQs for 458 participants (72%). Participants had a median age of 68 years (interquartile range 62 - 75). Three hundred eight (78%) were White, 72 (18%) were Black, 13 (3%) were other races/ethnicities: 65 did not report race. First-line treatment for mHSPC based on the PQ was most commonly ADT + ARPI (59%) followed by ADT + docetaxel (17%), ADT monotherapy (14%), ADT + first-generation antiandrogen (3%), ADT + ARPI + docetaxel (3%), and other treatments (5%). Overall, 384 (86%) participants received first-line treatment that was guideline concordant at the time of treatment. Treatment guideline concordance was highest in 2018 (99%) when ADT monotherapy was considered as guideline concordant but then decreased to 80% in 2019 and remained largely stable from 2019 to 2022 (85%). Overall, rates of guideline concordance were similar when stratified by race (88% for White patients vs 85% for Black patients), age (90% for patients &lt;65 years old vs 85% for patients ≥65 years old), and treatment at a Comprehensive Cancer Center (CCC) (87% at CCC vs 86% at non-CCC).
Conclusion: Among patients with mHSPC treated in the US at 38 cancer centers, proportions of guideline concordant first-line treatment were high and remained stable over time, despite changes in approved therapies. Future efforts to understand reasons for treatment decisions will be important to better understand the relatively uncommon situations in which guidelines and actually received treatments differ for patients with mHSPC.
Citation Format: Hannah Dzimitrowicz McManus, Lauren Howard, Kerri-Anne Crowell, Terry Hyslop, Jake Vinson, Dana E. Rathkopf, Philip Kantoff, Lorelei A. Mucci, Daniel George, Konrad Stopsack. Treatment guideline concordance for patients with metastatic hormone-sensitive prostate cancer (mHSPC) in the United States in IRONMAN, the International Registry for Men with Advanced Prostate Cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3812.