The presence and extent of metastatic disease play a central role in determining which and if any therapy is beneficial. Patients without metastatic disease have not been shown to benefit from aggressive systemic therapy. Further, clinicians should categorize patients as de novo metastatic disease or having progression in stage after prior failed treatment. Studies of systemic therapy have demonstrated that extent of metastatic disease influences response. For example, STAMPEDE demonstrated that only the subset of men with low-volume disease showed an improvement in survival with radiotherapy to the prostate in combination with ADT.74 As a result, presence of metastatic disease, its burden, and precise locations should be assessed prior to treatment. Patients diagnosed with higk-risk cancer defined by D’Amico risk factors (cT3a or greater, Grade Group 4/5, or PSA>20ng/mL) should undergo routine bone scan and cross-sectional imaging (CT or MRI) or PET imaging at the time of diagnosis. PSMA PET availability is increasing in the U.S. and detects metastatic disease at low PSA values. As outlined above, the extent and location of metastasis should be documented. Imaging should be repeated for men who undergo treatment at the time of PSA failure. It is notable that the median PSA at which metastasis is detected after curative intent is highly variable in some studies with a median of 31ng/mL and a range of 0.2 to 798.5ng/mL.75 Factors associated with rapid progression to metastatic disease include short PSADT, a high pathologic or biopsy Gleason score after radical prostatectomy, and a short interval to biochemical failure.51 In addition, it is notable that men with de novo metastases appear to do worse than men who develop metastatic disease subsequent to radiation or surgery. It is unknown if this is due to a therapeutic effect, lead time bias, or ascertainment bias. PET imaging detects metastatic disease at low PSA values and, therefore, has changed our ability to identify low-volume metastatic disease. 18F-Fluciclovine is available and approved for patients for whom local therapy fails to control disease. Men with PSA over 1.0ng/mL were found to have avid lesions in 57% of cases.76 68Ga-PSMA-11, 18F-DCFPyL, and 18F-rhPSMA-7.3 are indicated for patients with suspected prostate cancer metastasis considering local therapy and as well as for patients with suspected prostate cancer recurrence based on elevated serum PSA levels. Utilization of PSMA PET may lead to the diagnosis of metastatic disease not previously detected with conventional imaging. While this detection of metastases at lower PSA levels is helpful in guiding therapy, it is important to note that the clinical trials for treatment did not use PET imaging; therefore, it is unknown if volume of disease on PET imaging can accurately classify patients into high- and low-risk groups.