Survival Outcomes for Metastatic Prostate Cancer Patients Treated With Radical Prostatectomy or Radiation Therapy: A SEER-based Study.

Background: Patients with metastatic prostate cancer (mPCa) have a very low 5-year survival rate. How to choose proper treatment of mPCa remains controversial. Method: Within the Surveillance, Epidemiology, and End Results (SEER) database (2004-2015), we performed analyses of cancer-specific mortality (CSM) and overall mortality (OM) in the comparisons of local treatment (LT) versus no local treatment (NLT) and radical prostatectomy (RP) versus radiation therapy (RT). To balance the characteristics between 2 treatment groups, propensity score matching was performed. Considering the selection bias, we additionally used an instrument variate (IVA) to calculate the unmeasured confounders. Result: Multivariate regression showed that patients receiving LT had the lower risks of OM and CSM after adjustment of covariates (hazard ratio [HR] 0.39, 95% confidence interval [CI] 0.35-0.44 and HR 0.39, 95% CI 0.34-0.45). In the IVA-adjusted model, LT showed more survival benefits compared with NLT, with HR of 0.57 (95% CI 0.50-0.65) and cancer-specific HR of 0.59 (95% CI 0.51-0.68), respectively. For those receiving LT, adjusted multivariate regression indicated that RP is superior to RT (HR 0.60; 95% CI 0.43-0.83 for OM and HR 0.61; 95% CI 0.42-0.91 for CSM). The IVA-adjusted model also showed that RP presented with potentially better survival outcome compared with RT, although the effect was not statistically significant (HR 0.63; 95% CI 0.26-1.54 for OM and HR 0.47; 95% CI 0.16-1.35 for CSM).

Conclusion: Among patients with metastatic prostate cancer, LT might bring better survival benefits in decreasing CSM and all-cause mortality compared with NLT. For those receiving LT, RP showed better survival outcomes than RT.