Survival Trends for Patients with Primary Metastatic Prostate Cancer Before and After the Introduction of New Antitumor Drugs

Background: During the past two decades, new antitumor drugs (Abiraterone, Enzalutamide, Radium-223, Cabazitaxel, and Docetaxel) have been introduced for treatment of prostate cancer with distant metastases (mPCa). Each drug have demonstrated a survival gain in studies, but little is known about the impact in a general population of mPCa patients. In this study we assessed survival before and after introduction of the new drugs for Norwegian mPCa patients.

Methods: Survival was assessed in 5542 patients with primary mPCa. The patients were diagnosed between 2004 and 2018, identified in the Norwegian Cancer Registry. We also analyzed a subgroup of 2738 patients possibly eligible for treatment with new drugs (age <80 years, WHO performance status ≤2 and not dead within 3 months from diagnosis). We estimated overall (OS) and cause-specific survival (CSS) across three diagnostic time periods reflecting to the drugs' introduction in Norway: Before (2004-2009), "in between" (2010-2014) and after the introduction (2015-2018). We used Kaplan-Meier survival analysis and multivariable Cox regression.

Results: Median OS increased from 2.3 years in 2004-2009 to 3.3 years in 2015-2018. 3-year OS improved from 41% in 2004-2009 to 51% in 2015-2018. An earlier diagnostic period, a more advanced T stage, higher ISUP grade group, lower WHO status and higher PSA levels were associated with a lower CSS. Similar results was found for the subgroup.

Conclusions: Median OS of mPCa has increased by one year since 2004 for mPCa patients in Norway. Survival improvement persisted after adjustment for recognized prognostic factors and may be related to the introduction of new drugs in Norway.