Current Treatment Paradigms and Clinical Outcomes in Oligometastatic Prostate Cancer Patients: A Targeted Literature Review

CONTEXT: Prostate cancer is the most common noncutaneous malignancy among men in the USA and Europe. There is no consensus definition of oligometastatic prostate cancer (omPC), which is often considered in two subgroups, synchronous (de novo) and metachronous (oligorecurrent), and may include patients with a low metastatic disease burden. OBJECTIVE: To summarize the epidemiology, disease definitions, mortality/survival outcomes, and treatment characteristics in both clinical trial and real-world settings among patients with synchronous, metachronous, and mixed-subtype (ie, synchronous and metachronous or undefined type) omPC, as well as low burden disease states. EVIDENCE ACQUISITION: We searched MEDLINE and Embase to identify publications reporting on epidemiology, disease definitions, clinical outcomes, and treatment characteristics of omPC. Gray literature sources (eg, ClinicalTrials.gov) were searched for ongoing trials. EVIDENCE SYNTHESIS: We identified 105 publications. Disease definitions varied across publications and omPC subtypes on the number and location of lesions, type of imaging used, and type of oligometastatic disease. Most studies defined omPC as five or fewer metastatic lesions. Data on the epidemiology of omPC were limited. Mortality rates and overall survival tended to be worse among synchronous versus metachronous omPC cohorts. Progression-free survival was generally longer among synchronous than among metachronous omPC cohorts but was more similar at longer time points. A summary of ongoing clinical trials investigating a variety of local, metastasis-directed, and systemic therapies in men with omPC is also provided. CONCLUSIONS: Definitions of oligometastatic disease depend on the imaging technique used. Epidemiologic data for omPC are scarce. Survival rates differ between synchronous and metachronous cohorts, and heterogeneous treatment patterns result in varied outcomes. Ongoing clinical trials using modern imaging techniques are awaited and needed. PATIENT SUMMARY: Definitions of oligometastatic prostate cancer (omPC) vary depending on the imaging technique used. Different treatment patterns lead to different outcomes. Robust omPC epidemiologic data are lacking.