Association Between Sociodemographic Marginalization and Combination Therapy for Metastatic Hormone-Sensitive Prostate Cancer: Population-Based Cohort Study in Ontario, Canada

PURPOSE – Combination therapy, which adds docetaxel or androgen receptor pathway inhibitors (ARPIs) to androgen deprivation therapy, improves overall survival in patients with metastatic hormone-sensitive prostate cancer (mHSPC). Despite strong clinical evidence and guideline support, real-world use of these therapies remains suboptimal. The extent to which sociodemographic marginalization contributes to this gap in care is poorly understood.METHODS – We conducted a population-based cohort study in Ontario, Canada, including patients 66 years or older diagnosed with de novo mHSPC between 2014 and 2022. The primary exposure was marginalization, measured using the Ontario Marginalization Index (ON-MARG), which captures area-level socioeconomic disadvantage across four domains: residential instability, material deprivation, age and labor force participation, and racialized and newcomer populations. We used hierarchical logistic regression models to assess the association between ON-MARG and receipt of combination therapy, adjusting for demographic, clinical, and physician-level factors. A secondary exposure examined socioeconomic status using a hybrid measure combining rurality and urban income quintile.RESULTS – We included data from 6, 051 men. Higher overall ON-MARG scores were associated with lower odds of receiving combination therapy (odds ratio [OR], 0.91 [95% CI, 0.83 to 0.99]). The most pronounced disparity was observed in the domain capturing racialized and newcomer populations (OR, 0.89 [95% CI, 0.81 to 0.97). Patients residing in higher median household income urban areas had greater odds of combination therapy compared with rural residents (OR, 1.39 [95% CI, 1.08 to 1.79]).CONCLUSION – Despite universal health care, access to combination therapy for mHSPC remains inequitable, particularly among patients living in marginalized, rural, and/or low-income communities. These disparities underscore the need for equity-driven policy interventions to ensure that all patients with mHSPC benefit from life-prolonging treatment advances.