PSA plays a variety of roles, the most familiar being screening to detect prostate cancer at an early stage. PSA also helps to define the Stages of Blue. Another role of PSA is to detect cancer relapse after surgery or radiation. Lastly, rises or declines in PSA after hormone therapy or chemotherapy help determine whether a treatment is working...

Radiation delayed until PSA begins to rise is called salvage treatment. Salvage radiotherapy is given to patients whose PSA either fails to become undetectable after surgery, or if the PSA subsequently rises after...