Hello Alf,
The location of tumors are significant as related to metastatic potential. Tumors of the central zone can leak PSA and generate anxiety but are less prone to escape by physically breaking through the capsule. Still a escape route could happen through the blood vessels of the prostate.
Tumors of the peripheral zone, the most common ones, either invade the seminal vessicles or more readily at the apex of the gland. Although local invasion happens, surgery or RT can effectively deal with them.
Only few prostate cancer cells in thousands acquire the metastatic potential that gives them the ability to survive outside the gland. They can invade, generate a blood supply and proliferate while avoiding the immune system. These are the ones that have the capability to kill.
RalphV