The Impact of Local Treatment on Overall Survival in Patients with Metastatic Prostate Cancer on Diagnosis: A National Cancer Data Base Analysis

Abstract

Background The role of local treatment (LT) in patients with metastatic prostate cancer (mPCa) at diagnosis is controversial. Objective We set to evaluate the potential impact of LT on overall mortality (OM) in men with mPCa, and how this impact is influenced by tumor and patient characteristics. Design, settings, and participants A total of 15 501 patients with mPCa were identified in the National Cancer Data Base (2004–2012) and categorized in LT (radical prostatectomy or radiation therapy targeted to prostate) versus nonlocal treatment (NLT; all other patients). Outcome measurements and statistical analysis The two arms (LT vs NLT) were matched using propensity scores to minimize selection bias. To evaluate LT impact on OM in relation to baseline characteristics, first multivariable Cox regression analysis was used to predict OM in patients treated with NLT, then interaction between predicted OM risk and LT status was tested. Results and limitations Overall, 9.5% (n = 1470) of patients received LT. In the postpropensity matched cohorts, 3-yr OM-free survival was higher in the LT group versus the NLT group (69% vs 54%; p < 0.001). In multivariable Cox regression, the NLT group, age, and Charlson comorbidity index were predictors of OM (all p ≤ 0.03). This model was used to predict the 3-yr OM risk. The interaction between predicted OM and LT status was significant (p < 0.001). The benefit of LT on OM decreased progressively as predicted OM risk increased. Specifically, the 3-yr absolute improvement in OM-free survival was 15.7%, for patients with predicted OM risk ≤20% versus 0% for those with predicted OM risk ≥72%. Conclusions Men with mPCa at diagnosis benefit from LT in terms of OM. This is largely affected by baseline characteristics. Specifically, patients with a relatively low tumor risk and good general health status appear to benefit the most. Patient summary We used a large hospital-based database to evaluate which patients might benefit from local therapy when metastasized prostate cancer was present at diagnosis. Local therapy is associated with a survival benefit in men with less aggressive tumors and good general health.