Impact of the Site of Metastases on Survival in Patients with Metastatic Prostate Cancer.

BACKGROUND Limited data exist on the impact of the site of metastases on survival in patients with stage IV prostate cancer (PCa). OBJECTIVE To investigate the role of metastatic phenotype at presentation on mortality in stage IV PCa. DESIGN, SETTING, AND PARTICIPANTS Overall, 3857 patients presenting with metastatic PCa between 1991 and 2009, included in the Surveillance Epidemiology and End Results-Medicare database were evaluated. OUTCOME MEASUREMENTS AND STATISTIC ANALYSES Overall and cancer-specific survival rates were estimated in the overall population and after stratifying patients according to the metastatic site (lymph node [LN] alone, bone, visceral, or bone plus visceral). Multivariable Cox regression analyses tested the relationship between the site of metastases and survival. All analyses were repeated in a subcohort of patients with a single metastatic site involved. RESULTS AND LIMITATIONS Respectively, 2.8%, 80.2%, 6.1%, and 10.9% of patients presented with LN, bone, visceral, and bone plus visceral metastases at diagnosis. Respective median overall survival and cancer-specific survival were 43 mo and 61 mo for LN metastases, 24 mo and 32 mo for bone metastases, 16 mo and 26 mo for visceral metastases, and 14 mo and 19 mo for bone plus visceral metastases (p<0.001). In multivariable analyses, patients with visceral metastases had a significantly higher risk of overall and cancer-specific mortality versus those with exclusively LN metastases (p<0.001). The unfavorable impact of visceral metastases persisted in the oligometastatic subgroup. Our study is limited by its retrospective design. CONCLUSIONS Visceral involvement represents a negative prognostic factor and should be considered as a proxy of more aggressive disease in patients presenting with metastatic PCa. This parameter might indicate the need for additional systemic therapies in these individuals. PATIENT SUMMARY Patients with visceral metastases should be considered as affected by more aggressive disease and might benefit from the inclusion in clinical trials evaluating novel molecules.