Prostate-specific antigen (PSA) is a protein made by your prostate gland. Blood tests can measure the level of this protein to screen for prostate cancer and other prostate conditions. It can also be used during or after prostate cancer treatment to determine how well therapies have worked.

If you or someone you love has recently gone through prostate cancer treatment, you may have talked to an oncologist about monitoring PSA levels. Here’s what you need to know about why follow-up testing is important and what the results can mean. Understanding this information can help you know what to expect and have better discussions with your healthcare team.

PSA Testing After Prostate Cancer Treatment: What To Expect

After initial treatment for prostate cancer, your oncologist or urologist will likely ask you to get your PSA levels tested every three to six months. Regular testing may last for somewhere between three and five years. After that, your levels will probably be tested every year. However, your cancer care team may recommend a different testing schedule.

It’s vital to get all testing recommended in a timely manner to best monitor your condition.

How Long After Treatment Should PSA Testing Start?

Different doctors may have different ideas about how soon after treatment PSA testing should start. It can take a while for your PSA levels to go down, and how far down they go depends on the type of treatment you had. If you test too soon, it may appear that treatment wasn’t successful when, in fact, your body is still adjusting.

If you have prostatectomy surgery, the standard is to wait between six and eight weeks before you test your PSA. However, newer research indicates that monitoring PSA levels for at least three months may be needed before it’s clear how successful the surgery was.

It can take longer for PSA levels to drop after radiation therapy. Levels may continue going down for somewhere between two and five years.

PSA Levels After Surgery

A few months after a radical prostatectomy, your PSA levels should drop significantly to be undetectable or nearly so. PSA is measured in nanograms per milliliter (ng/mL).

If your levels are higher than 0.2 ng/mL, your cancer care team may be concerned and want to do more testing. Depending on whether your PSA was ever undetectable, the type of prostate cancer you had, and how fast your PSA levels are going up, even levels of 0.1 ng/mL may be of concern.

Sometimes, people worry when they still have detectable PSA after a prostatectomy. However, if these levels are stable and aren’t rising, your oncologist might not consider it worrying. Talk to your cancer care team about what your PSA level might mean and whether you should get additional testing.

If PSA Levels Rise After Surgery

Your doctor may choose to monitor rising PSA levels after your surgery to see how fast they’re rising. The faster they go up, the more concerned the healthcare professionals are likely to be. If your PSA levels go up slowly, it may mean that some prostate tissue has invaded other nearby organs, like your bladder, and was missed during your surgery. This tissue may grow and produce PSA. If this is the case, you and your doctor will discuss what treatment options are next.

PSA Levels After Radiation Therapy

Understanding PSA levels after radiation treatment (also known as radiotherapy) can be more complicated than after surgery. The goal of radiation therapy is to destroy the cancerous cells, not the entire prostate. This means that there will be some normal prostate cells left, and they will continue producing PSA.

Radiation will cause your PSA levels to go down, and eventually they’ll hit their lowest point, called the nadir. The nadir will be different for different people. Your doctors will monitor your PSA levels regularly to figure out exactly what that point is for your body.

Your PSA levels may go up and down a bit, especially if you’re younger. This means that they can seem like they’re going up, then start heading back down again. No one knows exactly why this happens, though it might be connected to inflammation in and around your prostate. Your cancer care team can help you understand what’s normal for your body.

If PSA Levels Rise After Radiation

If your PSA levels rise after radiation, your doctor may continue to monitor them for a while. Your doctor may not see a cause for concern unless your levels get to 2 ng/mL higher than your nadir. This helps take into account the normal cells still producing PSA, regular fluctuations in how your body works, and possible cancer cells that are still in your body. Depending on factors such as the type of prostate cancer you had, your doctor may recommend additional testing at any point.

What Happens if Your PSA Levels Are High

If you have elevated PSA levels after treatment, and your doctors are concerned that some cancer cells have survived and are producing PSA, this is known as a biochemical recurrence. If your care team suspects a biochemical recurrence, they’ll likely order imaging scans. These may include a computed tomography (CT) scan, a magnetic resonance imaging (MRI) scan, a bone scan, or a positron emission tomography (PET) scan. These different types of imaging scans allow your oncologist to check whether prostate cancer has returned (recurred) or spread.

PET scans are very sensitive and allow your doctors to find cancer at earlier stages, when your PSA is lower. Because of this, PET scans are becoming more and more common. All of these scans test for distant spread, also known as metastasis, which would mean the cancer has moved beyond your prostate.

If your doctors find that the cancer has recurred and spread, they’ll talk to you about further treatment options. These may include hormone therapy, immunotherapy, chemotherapy, targeted therapy, radiopharmaceutical therapy (radioactive drugs that destroy cancer cells), or some combination of these treatments. Most often, doctors will recommend hormonal therapy and might add another type of treatment, like immunotherapy, to your plan.

No matter what you choose, you have options when it comes to treating your prostate cancer. If one therapy stops working, you can try a different treatment. Your oncologists will work with you to figure out where to start and where to go next, if needed.

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