Doctors order PSA test in order to detect prostate cancer. Specifically, if you have prostate cancer and your urologist inhumanely remove your prostate totally, this does not mean that you are cancer-free. You are still at risk of developing prostate cancer recurrence. Right? It is now well known that with prostate recurrence, the PSA level would increase. In summary, doctors order PSA test in order to detect prostate cancer recurrence.