LAUSR

Simple Summary Oligometastatic prostate cancer has classically been defined as a small volume of prostate cancer spread as defined by imaging using CT, MRI, and bone scans. With development and integration of more sensitive functional imaging including PSMA-PET imaging more oligometastatic disease will be detected than was found with conventional imaging techniques. We are currently lacking data directing the best treatment course for these oligometastatic prostate cancer cases found on PET imaging who would have been defined as localized disease prior to PET imaging. Herein, we discuss the concept of stage migration and discuss current problems and challenges with the current definition of oligometastatic disease as imaging modalities have progressed in our field. Abstract Oligometastatic prostate cancer has traditionally been defined in the literature as a limited number of metastatic lesions (either to soft tissue or bone), typically based on findings seen on CT, MRI, and skeletal scintigraphy. Although definitions have varied among research studies, many important clinical trials have documented effective treatments and prognostication in patients with oligometastatic prostate cancer. In current clinical practice, prostate-specific membrane antigen (PSMA)-PET/CT is increasingly utilized for the initial staging of high-risk patients and, in many cases, detecting metastases that would have otherwise been undetected with conventional staging imaging. Thus, patients with presumed localized and/or oligometastatic prostate cancer undergo stage migration based on more novel molecular imaging. As a result, it is challenging to apply the data from the era before widespread PET utilization to current clinical practice and to relate current trials using PSMA-PET/CT for disease detection to older studies using conventional staging imaging alone. This manuscript aims to review the definition of oligometastatic prostate cancer, summarize important studies utilizing both PSMA-PET/CT and conventional anatomic imaging, discuss the concept of stage migration, and discuss current problems and challenges with the current definition of oligometastatic disease.