What Is Biochemical Recurrence of Prostate Cancer?
Biochemical recurrence means that your PSA level has started to rise after you’ve been treated for prostate cancer that was only in the prostate (localized).The definition of biochemical recurrence is different depending on whether your original treatment was surgery (radical prostatectomy) or radiation therapy.
When PSA begins to rise, your doctor may recommend more tests. These are to find out if the prostate cancer has returned and, if so, where it’s growing.
Why Might a PSMA PET/CT Scan Help?
In the past, doctors mainly used CT scans, bone scans, and MRI to look for prostate cancer after a rising PSA. These tests can still be helpful, but they may not be able to find very small areas of prostate cancer, especially when your PSA level is low.
A newer type of imaging test called a PSMA PET/CT scan can often find prostate cancer that can’t be seen with conventional imaging tests.
What is a PSMA PET/CT Scan?
A PET/CT scan combines two types of imaging:
- A positron emission tomography (PET) scan. This type of scan uses a small amount of radioactive material called a radiotracer to show areas of cell growth activity in the body.
- A computed tomography (CT) scan. This type of scan creates detailed pictures of the body's structures.
PSMA stands for prostate-specific membrane antigen. It’s a protein found on the surface of most prostate cancer cells.
For a PSMA PET/CT scan, you receive an injection of a small amount of a radioactive tracer that attaches to PSMA. A PET scanner can then detect where the tracer has collected. Because prostate cancer cells often have large amounts of PSMA, the scan can help doctors find areas of prostate cancer in the body.
PSMA PET/CT can be helpful when PSA levels are low and other imaging tests have not been able to find the cancer.
Three PSMA PET/CT tracers are commonly used in the United States:
- Piflufolastat F-18, also known by the brand name Pylarify
- Gallium-68 (Ga-68) PSMA-11, also known by the brand name Illuccix
- Flotufolastat F-18, also known by the brand name Posluma
All 3 options are FDA approved for use in men with prostate cancer, including men whose PSA has risen after treatment with surgery or radiation. The availability of each test can vary by area and medical center.
How Accurate Is a PSMA PET/CT Scan?
A PSMA PET/CT scan is generally better at finding recurrent prostate cancer cells than older types of imaging, especially when the PSA level is relatively low.
One key study was the CONDOR clinical trial. It included 208 men with biochemical recurrence whose conventional imaging tests had not been able to find prostate cancer. About two-thirds (68.8%) of the men in the study had PSA levels below 2.0 ng/mL. A Pylarify PSMA PET/CT scan found a possible cancer area in about 59% to 66% of the men. The scan results also changed the treatment plan for 64% of the men in the study.
What Do PSMA PET/CT Results Mean?
If you have a positive PSMA PET/CT scan result, it doesn’t mean you definitely have cancer. The scan can show a spot that absorbs the tracer. This may indicate prostate cancer, but it does not prove that cancer is present. Your doctor may advise having more testing, such as a biopsy.
And, a negative PSMA PET/CT does not prove that there is no cancer. Very small areas of cancer may be below the ability of the scan to detect. Your doctor will interpret your PSMA PET/CT results together with your PSA level, previous treatment, biopsy results, and other information about your prostate cancer.
How Might a PSMA PET/CT Change My Treatment Plan?
Knowing where prostate cancer may have returned can help your doctor choose the best treatment. For example, the scan may show:
- Cancer that appears to be only in the area where the prostate used to be
- Cancer in nearby lymph nodes
- Cancer in a small number of other places
- More widespread cancer
These findings can help your treatment team decide if treatments such as radiation therapy, hormone therapy, or other treatments may be right for you.
Talking with Your Healthcare Team
If your PSA begins to rise after treatment for prostate cancer, ask your doctor if a PSMA PET/CT scan would be helpful. The decision depends on several factors, including:
- Your PSA level and how quickly it’s rising
- Whether you originally had surgery or radiation
- Your original cancer's Grade Group and stage
- Your previous treatments
- What your doctor is considering for your next treatment
PSMA PET/CT can be helpful when your doctor needs to find out where a recurrence may be located before deciding on more treatment.
These interviews were produced with the generous support of Lantheus