PSA is a common marker used for:

• A. Screening
• B. Recurrence
• C. Monitoring therapy response
• D. All of the above

Answer: (D)

Prostate-specific antigen (PSA) is a blood biomarker used at multiple stages of prostate cancer care. It helps with screening to flag potential cancer in men, with monitoring how well therapy is working (a drop in PSA after treatment suggests effective control, while a rise can indicate progression), and with detecting recurrence after initial treatment (a rising PSA can signal biochemical recurrence before imaging shows a tumor). Because PSA provides information across these different phases, it’s appropriate to use it for all of the above. Remember that PSA can also rise due to non-cancer conditions like prostatitis or benign prostatic hyperplasia, so interpretation must consider the whole clinical picture.