Can a blood filtering technique reveal more about prostate cancer spread?

This study looks at whether a procedure called leukapheresis can collect more circulating tumor cells (CTCs) from the blood than a standard blood draw in men with metastatic prostate cancer. CTCs are cancer cells that break away from the tumor and travel in the bloodstream. The goal is to see which method gives a better sample for learning about the tumor's biology and how the cancer spreads. Participants will provide a small blood sample and undergo leukapheresis, a routine procedure that separates white blood cells (and CTCs) from the rest of the blood.