MP50-12 THE IMPACT OF LOCAL TREATMENT ON OVERALL MORTALITY IN PATIENTS DIAGNOSED WITH PRIMARY METASTATIC PROSTATE CANCER

Abstract

INTRODUCTION AND OBJECTIVES: The role of local treatment (LT) in prostate cancer (PCa) patients with M1 disease at diagnosis is controversial. We set to test the hypothesis that the potential efficacy of such treatment on overall mortality (OM) is influenced by tumor characteristics, as well as patient general health status. We based our analyses on the National cancer database (NCDB), which captures 70% of newly diagnosed tumors in US. METHODS: We focused on 16,274 PCa patients diagnosed with M1 disease, between 2004 and 2011, within the NCDB database. Men receiving radical prostatectomy, and/or radiotherapy targeted to prostate were categorized as LT, everybody else was categorized as non-local treatment (NLT). Multivariable regression analysis (MVA) including tumor and patient characteristics was used to predict OM in patients that received NLT. To assess whether the benefit of LT was different by baseline risk, we tested the interaction between predicted OM risk and LT status. RESULTS: Overall, 719 (4.4%) of patients received LT. Patients with NLT tended to be older, had higher comorbidity, and harbored more aggressive tumors. (all p 1 vs 0, respectively), PSA (HR 1.003), biopsy Gleason (HR 1.4 for 8-10 vs. 7), clinical stage (HR 1.09 for cT3/4 vs cT1/2), and clinical M stage (HR 1.5, and 1.9 for M1b vs M1a and M1c vs M1a, respectively) were independent predictors of OM (all p<.001). These variables were use to predict OM (c-index 89%), and plot it against observed survival (figure). The interaction between predicted OM, and LT status was significant (p<.001), which implies that LT impact on OM is influenced by tumor and patient characteristics that were included in the MVA model. CONCLUSIONS: Men with M1 PCa at diagnosis might benefit from LT in terms of OM. However, this is true only for patients with relatively low tumor risk, and good general health condition. Our model can help deciding which patients can benefit from LT. Specifically, those with predicted 3-year OM risk <70% seem to benefit the most.