Improved cancer-specific free survival and overall free survival in contemporary metastatic prostate cancer patients: a population-based study

Abstract

Objectives: Over the past decade, several systemic agents as docetaxel, cabazitaxel, sipuleucel-T, abiraterone and enzalutamide have improved overall survival (OS) in metastatic prostate cancer (mPCa) patients. However, to date the OS benefit was not demonstrated in population-based analysis.

Methods: Between 2004 and 2014, 19,047 men with de novo mPCa were identified within the Surveillance Epidemiology and End Results database. Median year of diagnosis resulted in two groups: historical (2004-2008) and contemporary (2009-2014). Due to potentially important differences according to year of diagnosis, we relied on propensity score matching. Propensity-score-matched Kaplan-Meier analyses and Cox regression models (CRMs) tested cancer-specific mortality (CSM) free survival and overall mortality (OM) free survival according to treatment period.

Results: The propensity-score-matched cohort consisted of 8596 patients with mPCa. Of those, 4298 (50.0%) were historical (2004-2008) and 4298 (50.0%) were contemporary (2009-2014). CSM free survival rates and OM free survival rate were 32 versus 36 months (p < 0.0001) and 26 versus 29 months (p < 0.0001) for, respectively, historical and contemporary patients. In multivariable CRMs, patients diagnosed in contemporary years had lower CSM (HR 0.88; CI 0.82-0.93) and OM (HR 0.88; CI 0.84-0.93) risks compared to historical counterpart (all p < 0.0001).

Conclusion: This population-based study provides the first evidence of improved CSM free survival and OM free survival in patients with de novo mPCa since the introduction of several systemic agents for CRPC patients.

Keywords: Adjuvant therapy; Castration-resistant prostate cancer; Metastatic prostate cancer; SEER Program; Systemic agents; Urology.