Your doctor will closely track how quickly your prostate-specific antigen (PSA) levels change over time. He may call this your "PSA velocity." It can be a sign of how extensive and aggressive your cancer is.
PSA levels can be confusing. They can go up and down for no obvious reason. They can rise after treatment -- and levels tend to be higher in older men and those with large prostates. Plus, the PSA blood test isn't precise. That's why doctors monitor your results over time instead of focusing on one test result.
Your doctor will also consider other things, including your PSA levels before you had cancer, your overall health, and whether you've had radiation therapy, which can raise your PSA levels for up to 2 years.
Each case is different, so ask your doctor about what your numbers mean. You'll want that perspective so you get the big picture of how you're doing.