Prostate Cancer

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Treating Prostate Cancer TOPICS

Following PSA levels during and after treatment

The prostate-specific antigen (PSA) level is often a good indicator of how effective treatment is or has been. Generally speaking, your PSA level should get very low after treatment. But PSA results aren't always cut and dry, and sometimes doctors aren't sure what they mean.

Before starting treatment, you might want to ask your doctor what he or she expects your PSA level to be during and after treatment, and what levels might be concerning. But it's important to realize that the PSA level is only one part of the overall picture. Other factors may also play a role in determining if cancer is still present or if it is growing.

It's also important to know that PSA levels may fluctuate a bit on their own in some cases. Many men being treated for prostate cancer are very concerned about even very small changes in their PSA levels. The blood PSA level is an important tool to monitor the cancer, but not every rise in PSA necessarily means that the cancer is growing and requires treatment right away. To help avoid possibly unnecessary anxiety, be sure you understand what level of change in PSA your doctor might consider to be a cause for concern.

During active surveillance

If you choose active surveillance, your PSA level will be monitored closely (most likely along with other tests) to help decide whether the cancer is growing and if other types of treatment should be considered. (See the section "Expectant management (watchful waiting) and active surveillance" for more details.)

After surgery

The PSA should fall to an undetectable level within a couple of months after radical prostatectomy. Because some PSA may remain in the blood for several weeks after surgery, even if all of the prostate cells were removed, doctors often advise waiting at least 6 to 8 weeks after surgery before getting the test.

Blood tests to detect PSA have become much more sensitive in recent years – so sensitive that they can detect very small amounts of PSA. This would seem to be a good thing, but it has made it more difficult to define exactly what an "undetectable" PSA level is. For example, a PSA of 0.5 (ng/mL) after surgery might be concerning, but doctors aren't sure whether this is also true of levels of 0.01 or 0.02. Some doctors would advise following such PSA levels over time to get a better idea of what may be going on, possibly with repeat tests every few months. Others might be more inclined to recommend further treatment. Of course, this uncertainty can be very stressful for patients and their families.

Having a detectable PSA level after surgery does not always mean that you still have cancer. If you have a low PSA level that is not rising, it could mean that you just have some benign prostate cells still in your body.

After radiation therapy

The different types of radiation therapy don't kill all of the cells in the prostate gland, so they're not expected to cause the PSA to drop to an undetectable level. The remaining normal prostate cells will continue to make some PSA.

The pattern of the drop in PSA is also different from after surgery. PSA levels after radiation tend to drop gradually, and may not reach their lowest level until 2 years or more after treatment.

Doctors tend to follow the PSA levels every few months to look for trends. A one-time, small rise in PSA might be a cause for closer monitoring, but it may not necessarily mean that the cancer has returned, as PSA levels may fluctuate slightly from time to time. However, a PSA that is rising on consecutive tests after treatment might indicate that cancer is still present. Some medical groups have proposed that if the PSA rises more than 2 (ng/mL) above the lowest level it reached, further treatment should be considered, but it's not clear if all doctors agree with this.

There is also a phenomenon called a "PSA bounce" that sometimes happens after brachytherapy. The PSA rises slightly for a short time within the first couple of years after treatment, but then falls back down. Doctors aren't sure why this happens, but it doesn't seem to have an effect on a patient's prognosis.

During treatment for advanced prostate cancer

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

Treatments should lower the PSA level (at least at first), although in some cases they may just help keep it from rising further, or even just slow the rise. Of course, other factors, such as whether you are having symptoms from your cancer and whether it is growing based on imaging tests, 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 whether it changes, and how quickly it changes. The PSA level itself does not predict whether or not a man will have symptoms or how long he will live. Many men have very high PSA values and feel just fine. Other men have low values and have symptoms.

Last Medical Review: 08/26/2013
Last Revised: 09/12/2014