Contemporary androgen deprivation therapy practice patterns in locally advanced prostate cancer treated with definitive radiotherapy: Prospective results from a statewide radiation oncology quality consortium.
Authors: Dykstra Michael , Regan Samuel , Yin Huiying , McLaughlin Patrick , Boike Thomas Pence , Bhatt Amit , Zaki Mark A. , Kendrick Danielle , Mislmani Mazen , Paluch Sarah , Litzenberg Dale , Mietzel Melissa A. , Narayana Vrinda , Smith Andrea , Heimburger David K. , Schipper Matthew J. , Jackson William C. , Dess Robert Timothy 
Published: January 2024

307 Background: Androgen Deprivation Therapy (ADT) is a critical treatment component for men with locally advanced prostate cancer receiving definitive radiotherapy. National guidelines recommend 18-36 months of ADT for men with high-risk disease, along with androgen receptor signaling inhibitors (ARSI) for those with very high-risk and clinical node positive disease. However, minimal data exist regarding treatment intent in the real-world setting. Given the rapid rate of scientific advances with respect to ADT types and duration, we hypothesized significant practice pattern variation. Using prospectively collected data, we sought to characterize patterns of care within the Michigan Radiation Oncology Quality Consortium (MROQC). Methods: This analysis includes men enrolled in MROQC with intact, non-metastatic, high-risk, or clinical node-positive (cN1) disease. Patient, tumor, and treatment data were prospectively collected at baseline and follow-up using standardized data elements. Physicians prospectively documented intent, type, and duration of ADT. Our primary outcome was guideline-concordant intended use ADT of ≥18 months. Secondary analyses included ARSI use among patients meeting eligibility for STAMPEDE high-risk M0/N1. Univariable (UVA) and multivariable (MVA) analyses were conducted to determine associations with T/N category, grade group, prostate specific antigen (PSA) and practice-related factors. Results: Between 6/9/20 to 6/30/23, 234 men across 26 centers were identified, all of whom should receive ≥18 months of ADT per NCCN guidelines. Eight percent (18/234) had locally advanced T3/4 disease, and 8% (n=18/234) had cN1 disease. Most men had grade group 4 (48%, n=112/234) or 5 (24%, n=56) adenocarcinoma. Intended ADT duration was known for 88% (n=207). ADT use ≥18 months was planned for 56% (n=115/207), <18 months in 30% (n=63/207), and no ADT was intended for 14% (n=29/207) of men. On MVA, grade group 4-5 and PSA >40 were the strongest drivers of guideline-concordant intended ADT. There were no significant associations with comorbidities or race. STAMPEDE M0/cN1 criteria were met for 15% (n=36/234). Intended ARSI use in this subset was 19% (n=7/36), including 26% (n=6/23) of patients treated after publication of STAMPEDE M0/N1. Conclusions: Within a diverse state-wide consortium of academic and community practice, guideline concordant intended ADT use was 56% and was associated with higher risk tumor features. Fewer than 1 in 5 treated with curative intent radiotherapy met STAMPEDE high-risk M0/N1 criteria, and ARSI use among these men was less than 20%. Future work will evaluate patient and practice level drivers of the variation. [Table: see text]