In a patient with newly diagnosed high risk prostate cancer, how do you work up a bone scan showing suspicious areas of radiotracer uptake?

This a great question.  In the setting of abnormalities on the bone scan, I would take 2 actions.  First, I would certainly get local imaging of the abnormal site, with a CT, MRI or X-ray, depending on the location.  I would also use the patient's clinical scenario and treatment response to help in the decision making process, especially if the imaging is indeterminate.   

I would start with an X-ray of the affected area.  If the uptake is in the skull, I would consider a CT.  MRI may be used as an adjunct, especially if the disease is in the extremity and may help if there is a pathologic or an impending fracture that will warrant and orthopaedic oncology intervention. Typically the orthopaedic oncologists will want the MRI for surgical planning.

If the imaging is still indeterminate, then my clinical practice has been to typically reassess after neoadjuvant hormone therapy has been administered with repeat imaging and PSA.  If the disease has shown regression on imaging and with PSA, then it was likely a metastatic deposit.  If there is no change in imaging, then it should be watched, but likely insignificant. 

Regardless, there is now data in the setting of metastatic disease in prostate (especially a low metastatic burden) and various other malignancies to treat both the primary and metastatic focus if one does discover disease outside the primary area (Parker CC, Lancet, 2018; Palma DA, Lancet, 2019) .