Following PSA Levels During and After Prostate Cancer Treatment

Changes in PSA (prostate-specific antigen) levels can help doctors monitor prostate cancer before, during, and after treatment. A small rise does not always mean the cancer is growing, so doctors often look for trends over time. What a change in PSA might mean also depends on the type of treatment you had, how quickly PSA is changing, and other test results.

How important are PSA levels for monitoring prostate cancer?

After treatment, the PSA (prostate-specific antigen) level in your blood should get very low. This is often a good indicator of how effective treatment has been. But your PSA level is only one part of the overall picture.

Other factors can also play a role in determining if cancer is still there, if it is growing, or if it has come back. Newer imaging tests, such as PSMA PET scans, can now often find where the cancer is even when the PSA level is still very low. Your doctor may use one of these scans along with your PSA results to get a clearer picture.

PSA levels can sometimes fluctuate a bit on their own, even during or after treatment, so they may not always be an accurate sign of what is happening with your cancer. It’s normal to feel concerned about even small changes in your PSA levels, but not every rise in PSA means that the cancer is growing and requires treatment right away.

Before starting treatment, you might want to ask your doctor what your PSA level is expected to be during and after treatment, and what levels might cause concern.

PSA levels during active surveillance or observation

If you choose active surveillance or observation, your PSA level will be monitored closely (most likely along with other tests) to help decide whether the cancer is growing and if treatment should be considered.

Not all doctors agree on exactly what PSA level might require further action (such as a prostate biopsy or treatment). Some doctors might look for a set number, while others might focus more on how quickly the PSA is rising.

Talk to your doctor so you understand what change in your PSA might be considered cause for concern.

PSA levels after prostate cancer surgery

Your PSA should fall to a very low or even undetectable level within a couple of months after radical prostatectomy. Because some PSA can remain in the blood for several weeks after surgery, even if all the prostate cells were removed, doctors often advise waiting at least 6 to 8 weeks after surgery before checking the PSA level.

Some men might worry if their PSA is still detectable even at a very low level after surgery, but this does not always mean cancer is still there. Modern PSA blood tests can detect even tiny amounts of PSA, but these amounts might not always be significant, especially if they are not rising over time. It could just mean that you have some cells in the body making PSA, but these aren’t necessarily cancer cells.

Still, having any detectable PSA after surgery can be stressful. If your PSA is still detectable after surgery, even at a very low level, talk to your doctor about what it might mean, and what the best course of action might be. Some doctors advise following such low PSA levels over time to get a better idea of what’s going on. Other doctors might recommend further treatment.

If your PSA increases after surgery, your doctor might also want to know how fast it is rising. Some evidence shows that faster-rising PSA levels may be more of a concern. Men who have a shorter PSA doubling time (the time it takes for the PSA level to double) tend to have a worse prognosis (outlook) compared to men with longer PSA doubling times.

PSA levels after radiation therapy

Radiation therapy doesn’t kill all of the cells in the prostate gland, so it's not expected to cause the PSA to drop to an undetectable level. The remaining normal prostate cells will still make some PSA.

PSA levels after radiation tend to drop slowly, and they might not reach their lowest level until 2 years or more after treatment.

PSA levels can fluctuate slightly from time to time. Doctors tend to follow the PSA levels every few months to look for trends.

• A one-time, small rise in PSA might be cause for closer monitoring, but it might not mean that the cancer is still there or has returned.
• However, a PSA that is rising on consecutive tests after treatment might indicate that cancer is still there.

Some medical groups have proposed that if the PSA rises more than 2 ng/mL above the lowest level reached, further treatment should be considered. But some doctors might recommend tests to look for cancer even if the PSA has not yet risen this much.

As is the case after surgery, if your PSA begins to rise after radiation treatment, your doctor might also want to know how fast it is rising. Men who have a shorter PSA doubling time (the time it takes for the PSA level to double) tend to have a worse prognosis (outlook) compared to men with longer PSA doubling times.

PSA bounce after radiation therapy

Sometimes the PSA level rises slightly for a short time within the first couple of years after radiation treatment, but then goes back down. This is called PSA bounce. Doctors aren’t sure why this happens, but it doesn’t seem to affect a man’s prognosis.

PSA levels during treatment for advanced prostate cancer

When treatments such as hormone therapy, chemotherapy, or immunotherapy are used for more advanced prostate cancer, the PSA level can help show how well the treatment is working or when it might be time to try a different treatment.

Treatments should lower the PSA level (at least at first), although in some cases they may only help keep it from rising further, or even just slow the rise. Of course, other factors, such as whether you’re having symptoms from your cancer and whether imaging tests show it is growing, are also important when deciding if it might be time to change treatments.

If the cancer has spread outside the prostate, the actual PSA level is often not as important as the direction and speed with which it changes. The PSA level itself does not predict whether a man will have symptoms or how long he will live. Many men have very high PSA levels and feel just fine, while other men with low PSA levels might have symptoms.