Recent Trends in the Use of Androgen Deprivation Therapy with External Beam Radiation Therapy for Patients with Intermediate- and High-Risk Prostate Cancer

Abstract

Androgen deprivation therapy (ADT), when given with external beam radiation therapy (EBRT), improves overall survival for men with unfavorable intermediate- and high-risk prostate cancer. However, previous studies suggest that a significant proportion of patients with aggressive prostate cancer do not receive ADT, likely due to concerns regarding its side-effects, particularly the potential for cardiovascular morbidity and mortality. Therefore, we examined recent trends in the use of ADT for patients with intermediate- or high-risk disease treated with EBRT. We identified 144,957 men diagnosed with intermediate-risk (Gleason 7, prostate-specific antigen 10-20 ng/mL, or cT2b-T2c stage) or high-risk prostate cancer (Gleason 8-10, prostate-specific antigen >20 ng/mL, or cT3-T4 stage) from 2004-2015 and treated with EBRT only. For patients diagnosed from 2010-2015, for which information on biopsy cores was available, intermediate-risk disease was categorized as favorable intermediate-risk (Gleason ≤3+4, <50% positive biopsy cores, and 1 intermediate-risk factor) or unfavorable intermediate-risk (all other intermediate-risk patients). Temporal trends were analyzed using interrupted time series. Overall, 40.3% of intermediate-risk patients and 78.4% of high-risk patients diagnosed from 2004-2015 received ADT with EBRT. From 2004-2011, ADT use decreased by 2.7% and 0.5% per year for intermediate- and high-risk patients, respectively. With the publication of a meta-analysis of randomized controlled trials in 2011 suggesting that ADT was not associated with increased cardiovascular mortality, ADT use increased by 3.8% (P <0.001) and 1.8% (P =0.001) per year compared to the previous trend for intermediate- and high-risk patients, respectively, from 2011-2015. Most recently in 2015, 27.0%, 67.5%, and 84.3% of favorable intermediate-risk, unfavorable intermediate-risk, and high-risk patients treated with dose-escalated EBRT (75.6-86.4 Gy) received ADT. ADT use with EBRT has significantly increased since 2011 for men with intermediate- and high-risk prostate cancer. However, many patients with unfavorable-risk disease treated with EBRT still do not receive ADT despite the well-documented survival benefit. Additional work is necessary to further understand why a large proportion of patients with unfavorable-risk disease do not receive ADT.