BackgroundRecent advancements in the clinical management of metastatic prostate cancer include several costly therapies and diagnostic tests. The objective of this study was to provide updated information on the cost to payers attributable to metastatic prostate cancer among men aged 18 to 64 years with employer‐sponsored health plans and men aged 18 years or older covered by employer‐sponsored Medicare supplement insurance.MethodsBy using Merative MarketScan commercial and Medicare supplemental data for 2009–2019, the authors calculated differences in spending between men with metastatic prostate cancer and their matched, prostate cancer‐free controls, adjusting for age, enrollment length, comorbidities, and inflation to 2019 US dollars.ResultsThe authors compared 9011 patients who had metastatic prostate cancer and were covered by commercial insurance plans with a group of 44,934 matched controls and also compared 17,899 patients who had metastatic prostate cancer and were covered by employer‐sponsored Medicare supplement plans with a group of 87,884 matched controls. The mean age of patients with metastatic prostate cancer was 58.5 years in the commercial samples and 77.8 years in the Medicare supplement samples. Annual spending attributable to metastatic prostate cancer was $55,949 per person‐year (95% confidence interval [CI], $54,074–$57,825 per person‐year) in the commercial population and $43,682 per person‐year (95% CI, $42,022–$45,342 per person‐year) in the population covered by Medicare supplement plans, both in 2019 US dollars.ConclusionsThe cost burden attributable to metastatic prostate cancer exceeds $55,000 per person‐year among men with employer‐sponsored health insurance and $43,000 among those covered by employer‐sponsored Medicare supplement plans. These estimates can improve the precision of value assessments of clinical and policy approaches to the prevention, screening, and treatment of prostate cancer in the United States.