PSA Doubling Times and Prostate Cancer Relapse

If you or someone you're close to has prostate cancer, you'll hear a lot about the PSA blood test and the PSA doubling time (PSADT). PSA helps medical providers screen for and diagnose prostate cancer at an early stage.

But there's more to the test than just that. The PSADT—a measurement of how quickly the PSA is increasing—is especially important after you've been treated for prostate cancer.

This article will walk you through why the PSA doubling time is so significant, how your doctors will use it to monitor for recurrence, and what factors will play a role in how a recurrence is treated.

Why PSA Is Important

PSA plays many different roles. The most common is determining prostate cancer risk.

PSA is also used to help determine the stage of a newly diagnosed prostate cancer. Staging is a measurement of how advanced the disease is.

The PSA doubling time can also detect a relapse of cancer after treatment with surgery or radiation.

The time it takes for PSA blood levels to double gives your medical team an insight into how aggressive your prostate cancer will be in the future. 

That can guide your treatment plan, which may include:

• Observation
• Radiation
• Cryotherapy
• Testosterone deprivation therapy with Lupron Depot (leuprolide acetate)
• Chemotherapy

Detecting a Relapse

PSA is useful for detecting a relapse of prostate cancer after surgery or radiation. After prostate cancer surgery, PSA is normally undetectable, and even small rises could point to a recurrence. 

After curative radiation, the PSA generally stays under 1.0 long-term. However, there are exceptions. Sometimes, the PSA level drops slowly after radiation and it may take years to reach its lowest point.

Younger people may have a short-term PSA rise that's not cancer-related. That's more common after the seed-implant type of radiation. This temporary rise is called a "PSA bump" or "bounce." It can develop between one and four years after treatment.

It may be linked with anti-cancer activity in the immune system, which is a good thing. However, it's sometimes mistaken for a recurrence, which can lead to fear, stress, and even unnecessary hormone therapy. 

What Guides Treatment

When cancer comes back, the PSADT is an indicator of how fast it's growing.

Ultimately, relapse treatment is guided by: 

• The PSADT
• Your original (pre-treatment) risk category
• The tumor's location
• Whether you originally had surgery or radiation

Your age, other illnesses, and overall health will also be considered.

PSADT

The PSA doubling time has a big influence on treatment. There are treatments for men whose prostate cancer had recurred and is getting worse despite anti-hormonal treatment with Lupron Depot.

Treatments for recurrence of prostate cancer that hasn't spread:

• PSADT of 10+ months: Observation is generally preferred. Secondary hormone therapy can be considered.
• PSADT of three to 10 months: Treatment with Erleada (apalutamide), Nubeqa (darolutamide), or Xtandi (enzalutamide) is preferred. Additional secondary hormone therapy is also recommended.
• PSADT of three months or less: Treatment should be aggressive, such as six cycles of Taxotere (docetaxel) along with Lupron Depot. Some medical providers may consider new drugs like Zytiga (abiraterone acetate), Xtandi, or Orgovyx (relugolix).

Original Risk Category

Your original risk category will also play a role in treatment decisions.

Risk categories:

• Low risk: Cancer is confined to the prostate, PSA is less than 10 and grade group 1, or the tumor is very slow-growing.
• Intermediate risk: Cancer is confined to the prostate, PSA is between 10 and 20, or grade group 2 or 3.
• High risk: Cancer extends outside the prostate, PSA is higher than 20, or grade group 4 o r 5; or the tumor is very aggressive and has spread to other areas.

The higher the risk, the more aggressive the treatment. For example, if you were originally low risk, your treatment may include either cryotherapy, radiation, or Lupron Depot alone if cancer is confined to the prostate (after radiation) or the prostatic bed (after prior surgery).

If you were originally in the high-risk category, treatment may mean Lupron Depot plus pelvic lymph node radiation.

Tumor Location

If you have a rising PSA after surgery or radiation, your doctor will likely order imaging studies to find the location of your cancer recurrence.

Common scans are:

• PET scans using axumin, C11 acetate, or choline
• Color Doppler ultrasound or 3D MRI techniques to spot residual cancer.
• Pelvic MRI or CT scans can show spreading to pelvic lymph nodes.
• New F18 PET bone scans can detect much smaller cancers than older types.

Cancer in the prostate or prostate bed is considered a local recurrence. Cancer that's spread outside of that area is called metastatic.

Treatment of metastatic recurrence depends on where it is and many other factors.

With a local relapse, disease suppression with Lupron Depot is an option.

That's especially true if you have a:

• High PSA
• Short PSADT
• Otherwise long life expectancy

Lupron Depot alone is almost never a cure, but it often controls the disease for more than a decade.

Post-Surgery

Generally, if you were low-risk or intermediate-risk before surgery and develop a PSADT of between six and 12 months, your recurrence has a good chance of being cured with radiation treatment to the prostate bed.

Radiation is most effective when the PSA level is low and the PSADT is long without evidence of spread/metastases on imaging studies.

If you want to avoid radiation side effects, another option is to suppress the PSA with an intermittent, six-month course of Lupron Depot.

If your PSA doubling time is faster—for example, under six months—your medical provider is likely to recommend pelvic-node radiation plus Lupron Depot for as long as 12 to 18 months.

If you were high-risk before surgery, treatment will often be node radiation with 12 to 18 months of Lupron Depot. Your medical provider may suggest adding more powerful drugs like Zytiga, Xtandi, or Taxotere.

Post-Radiation

For a rising PSA after radiation, a popular approach is cryosurgery (freezing cancer cells). Newer scans help the cryosurgeon focus on cancerous areas, rather than treating the whole prostate. 

This is called focal cryotherapy. It offers much fewer side effects than freezing or removing the whole gland.

Another alternative is prompt treatment with Lupron Depot. This can suppress the local disease.

It's considered reasonable when:

• The PSADT is longer than six months
• The original risk category was either low or intermediate

If you were originally high risk, a local relapse should be treated aggressively with cryosurgery or seed implantation. Lupron Depot alone is less likely to work.

The prostate is rarely removed after radiation, due to high rates of incontinence and erectile dysfunction. 

Summary

Deciding on a treatment for a PSA relapse is complex. The choice is based on factors including your original risk category, PSA doubling time, and scan findings. The location of recurrent cancer may remain uncertain, even with the best scans. 

Treatment with cryosurgery or radiation alone is reasonable when:

• Scans indicate that cancer hasn't spread to the nodes.
• The previous risk category was low or moderate.
• The PSADT is long.

Microscopic metastases in the pelvic nodes don't always show up on scans. 

They're more likely if:

• The PSADT is fast.
• The previous risk category was high.

In these situations, pelvic lymph node radiation plus an extended course of Lupron Depot is usually recommended.

A Word From Verywell

Cancer is always serious, but the overall outlook of prostate cancer is often positive. Most people with prostate cancer have a good 15-year prognosis.

Sometimes, prostate cancer can be cured. Even when it's not, it can be controlled for years and even decades.

Keep up with your monitoring tests, including the PSA doubling time, is a key component of staying well in the long term.