Improvement in overall and cancer-specific survival in contemporary, metastatic prostate cancer chemotherapy exposed patients

INTRODUCTION: Over the last decade, multiple clinical trials demonstrated improved survival after chemotherapy for metastatic prostate cancer (mPCa). However, real-world data validating this effect within large-scale epidemiological data sets are scarce. We addressed this void.

MATERIALS AND METHODS: Men with de novo mPCa were identified and systemic chemotherapy status was ascertained within the Surveillance, Epidemiology, and End Results database (2004-2016). Patients were divided between historical (2004-2013) versus contemporary (2014-2016). Chemotherapy rates were plotted over time. Kaplan-Meier plots and Cox regression models with additional multivariable adjustments addressed overall and cancer-specific mortality. All tests were repeated in propensity-matched analyses.

RESULTS: Overall, 19,913 patients had de novo mPCa between 2004 and 2016. Of those, 1838 patients received chemotherapy. Of 1838 chemotherapy-exposed patients, 903 were historical, whereas 905 were contemporary. Chemotherapy rates increased from 5% to 25% over time. Median overall survival was not reached in contemporary patients versus was 24 months in historical patients (hazard ratio [HR]: 0.55, p < 0.001). After propensity score matching and additional multivariable adjustment (age, prostate-specific antigen, GGG, cT-stage, cN-stage, cM-stage, and local treatment) a HR of 0.55 (p < 0.001) was recorded. Analyses were repeated for cancer-specific mortality after adjustment for other cause mortality in competing risks regression models and recorded virtually the same findings before and after propensity score matching (HR: 0.55, p < 0.001).

CONCLUSIONS: In mPCa patients, chemotherapy rates increased over time. A concomitant increase in survival was also recorded.