Risk Factors for Early Treatment Discontinuation Due to Toxicity Among Patients With Metastatic Castration-resistant Prostate Cancer Receiving Androgen Receptor–targeted Therapy

Abstract

Background: Androgen receptor–targeted therapies (ARTs) improve survival outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC); however, a significant portion of patients discontinue treatment for various reasons including treatment-related toxicity. We aim to describe reasons for ART treatment discontinuation and identify predictors associated with increased risk of treatment discontinuation due to toxicity. Methods: We performed a single-institution retrospective review of patients with mCRPC receiving ART between 2010 and 2021. Our primary aim was to identify risk factors for treatment discontinuation due to toxicity. Our secondary aim was to describe ART discontinuation patterns among patients with mCRPC. Results: One hundred thirty-three patients with mCRPC started and discontinued ARTs. Fourteen patients (10.5%) discontinued treatment due to toxicity. Common reasons for treatment discontinuation include Prostate Specific Antigen test progression, radiographic progression, toxicity, and death. Significant predictors of treatment discontinuation due to toxicity on bivariate analysis and multivariate analysis included patient-reported falls (odds ratio [OR]: 7.67, CI: [1.31-40.42]; P=0.016), rash (OR: 13.4, CI: [1.35-134.81]; P=0.026), and weakness (OR: 4.16, CI: [1.15-15.0]; P=0.019). Conclusions: Our work presents the first description of ART treatment discontinuation and its causes in the real-world setting, as well as patient-reported side effects. Most patients with mCRPC discontinued treatment due to the progression of disease and a minority of patients discontinued secondary to treatment toxicity. Initial multivariable analysis suggests that patient-reported weakness, falls, and rash were associated with a higher likelihood of treatment discontinuation due to toxicity. Early monitoring of this population can prolong the duration of treatment and prevent unnecessary treatment burden.