Cancer cells sometimes break away from the original tumor and go to a blood or lymph vessel. Once there, they move through your body. The cells stop in capillaries -- tiny blood vessels -- at some distant location.
The cells then break through the wall of the blood vessel and attach to whatever tissue they find. They multiply and grow new blood vessels to bring nutrients to the new tumor. Prostate cancer prefers to grow in specific areas, such as lymph nodes or in the ribs, pelvic bones, and spine.
Most break-away cancer cells form new tumors. Many others don't survive in the bloodstream. Some die at the site of the new tissue. Others may lie inactive for years or never become active.